Review Of Forensic Science: 1200 words and three scholarly references

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Criminalistics An Introduction to Forensic Science

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Boston Columbus Indianapolis New York San Francisco Upper Saddle River Amsterdam Cape Town Dubai London Madrid Milan Munich Paris Montréal Toronto

Delhi Mexico City São Paulo Sydney Hong Kong Seoul Singapore Taipei Tokyo

Richard Saferstein, Ph.D. Forensic Science Consultant, Mt. Laurel, New Jersey

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After studying this chapter you should be able to: Define and distinguish forensic science and criminalistics

Recognize the major contributors to the development of forensic science

Account for the rapid growth of forensic laboratories in the past forty years

Describe the services of a typical comprehensive crime labora- tory in the criminal justice system

Compare and contrast the Frye and Daubert decisions relating to the admissibility of scientific evidence in the courtroom

Explain the role and responsibilities of the expert witness

Understand what specialized forensic services, aside from the crime laboratory, are generally available to law enforcement personnel

introduction

expert witness Locard’s exchange

principle scientific method

KEY TERMS

chapter 1

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4 CHAPTER 1

Definition and Scope of Forensic Science Forensic science in its broadest definition is the application of science to law. As our society has grown more complex, it has become more dependent on rules of law to regulate the activities of its members. Forensic science applies the knowledge and technology of science to the definition and enforcement of such laws.

Each year, as government finds it increasingly necessary to regulate the activities that most intimately influence our daily lives, science merges more closely with civil and criminal law. Consider, for example, the laws and agencies that regulate the quality of our food, the nature and potency of drugs, the extent of automobile emissions, the kind of fuel oil we burn, the purity of our drinking water, and the pesticides we use on our crops and plants. It would be difficult to conceive of a food or drug regulation or environmental protection act that could be effectively monitored and enforced without the assistance of scientific technology and the skill of the sci- entific community.

Laws are continually being broadened and revised to counter the alarming increase in crime rates. In response to public concern, law enforcement agencies have expanded their patrol and investigative functions, hoping to stem the rising tide of crime. At the same time, they are look- ing more to the scientific community for advice and technical support for their efforts. Can the technology that put astronauts on the moon, split the atom, and eradicated most dreaded diseases be enlisted in this critical battle?

Unfortunately, science cannot offer final and authoritative solutions to problems that stem from a maze of social and psychological factors. However, as the content of this book attests, science occupies an important and unique role in the criminal justice system—a role that relates to the scientist’s ability to supply accurate and objective information about the events that have occurred at a crime scene. A good deal of work remains to be done if the full potential of science as applied to criminal investigations is to be realized.

Because of the vast array of civil and criminal laws that regulate society, forensic science, in its broadest sense, has become so comprehensive a subject that a meaningful introductory text- book treating its role and techniques would be difficult to create and probably overwhelming to read. For this reason, we have narrowed the scope of the subject according to the most common definition: Forensic science is the application of science to the criminal and civil laws that are enforced by police agencies in a criminal justice system. Forensic science is an umbrella term encompassing a myriad of professions that use their skills to aid law enforcement officials in conducting their investigations.

The diversity of professions practicing forensic science is illustrated by the eleven sections of the American Academy of Forensic Science, the largest forensic science organization in the world:

1. Criminalistics 2. Digital and Multimedia Sciences 3. Engineering Science 4. General 5. Jurisprudence 6. Odontology 7. Pathology/Biology 8. Physical Anthropology 9. Psychiatry/Behavioral Science 10. Questioned Documents 11. Toxicology

Even this list of professions is not exclusive. It does not encompass skills such as fingerprint examination, firearm and tool mark examination, and photography.

Obviously, to author a book covering all of the major activities of forensic science as they apply to the enforcement of criminal and civil laws by police agencies would be a major undertaking. Thus, this book will further restrict itself to discussions of the subjects of chemistry, biology, physics, geology, and computer technology, which are useful for determining the evidential value of crime-scene and related evidence. Forensic psychology, anthropology, and

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odontology also encompass important and relevant areas of knowledge and practice in law enforcement, each being an integral part of the total forensic science service that is provided to any up-to-date criminal justice system. However, these subjects go beyond the intended scope of this book, and except for brief discussions, along with pointing the reader to relevant websites, the reader is referred elsewhere for discussions of their applications and techniques. Instead, this book focuses on the services of what has popularly become known as the crime laboratory, where the principles and techniques of the physical and natural sciences are practiced and applied to the analysis of crime-scene evidence.

For many, the term criminalistics seems more descriptive than forensic science for describ- ing the services of a crime laboratory. Regardless of his or her title—criminalist or forensic scientist—the trend of events has made the scientist in the crime laboratory an active participant in the criminal justice system.

Prime-time television shows like CSI: Crime Scene Investigation have greatly increased the public’s awareness of the use of science in criminal and civil investigations (Figure 1–1). However, by simplifying scientific procedures to fit the allotted airtime, these shows have created within both the public and the legal community unrealistic expectations of forensic science. In these shows, members of the CSI team collect evidence at the crime scene, pro- cess all evidence, question witnesses, interrogate suspects, carry out search warrants, and testify in court. In the real world, these tasks are almost always delegated to different people in different parts of the criminal justice system. Procedures that in reality could take days, weeks, months, or years appear on these shows to take mere minutes. This false image is sig- nificantly responsible for the public’s high interest in and expectations for DNA evidence.

The dramatization of forensic science on television has led the public to believe that every crime scene will yield forensic evidence, and it produces unrealistic expectations that a prosecu- tor’s case should always be bolstered and supported by forensic evidence. This phenomenon is known as the “CSI effect.” Some jurists have come to believe that this phenomenon ultimately detracts from the search for truth and justice in the courtroom.

FIGURE 1–1 A scene from CSI, a forensic science television show.

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6 CHAPTER 1

History and Development of Forensic Science Forensic science owes its origins first to the individuals who developed the principles and tech- niques needed to identify or compare physical evidence, and second to those who recognized the need to merge these principles into a coherent discipline that could be practically applied to a criminal justice system.

Literary Roots Today many believe that Sir Arthur Conan Doyle had a considerable influence on popularizing sci- entific crime-detection methods through his fictional character Sherlock Holmes (see Figure 1–2),

who first applied the newly developing principles of serology (see Chapter 14), fingerprinting, firearms identification, and questioned- document examination long before their value was first recognized and accepted by real-life criminal investigators. Holmes’s feats excited the imagination of an emerging generation of forensic scientists and crim- inal investigators. Even in the first Sherlock Holmes novel, A Study in Scarlet, published in 1887, we find examples of Doyle’s uncanny ability to describe scientific methods of detection years before they were actually discovered and implemented. For instance, here Holmes probes and recognizes the potential usefulness of forensic serology to criminal investigation:

“I’ve found it. I’ve found it,” he shouted to my companion, run- ning towards us with a test tube in his hand. “I have found a re- agent which is precipitated by hemoglobin and by nothing else. . . . Why, man, it is the most practical medico-legal discovery for years. Don’t you see that it gives us an infallible test for blood stains? . . . The old guaiacum test was very clumsy and uncertain. So is the microscopic examination for blood corpuscles. The lat- ter is valueless if the stains are a few hours old. Now, this appears to act as well whether the blood is old or new. Had this test been invented, there are hundreds of men now walking the earth who would long ago have paid the penalty of their crimes. . . . Criminal cases are continually hinging upon that one point. A man is sus- pected of a crime months perhaps after it has been committed. His linen or clothes are examined and brownish stains discovered upon them. Are they blood stains, or rust stains, or fruit stains, or what are they? That is a question which has puzzled many an expert, and why? Because there was no reliable test. Now we have the Sherlock Holmes test, and there will no longer be any difficulty.”

Important Contributors to Forensic Science Many people can be cited for their specific contributions to the field of forensic science. The following is just a brief list of those who made the earliest contributions to formulating the disciplines that now constitute forensic science.

MATHIEU ORFILA (1787–1853) Orfila is considered the father of forensic toxicology. A native of Spain, he ultimately became a renowned teacher of medicine in France. In 1814, Orfila published the first scientific treatise on the detection of poisons and their effects on animals. This treatise established forensic toxicology as a legitimate scientific endeavor.

ALPHONSE BERTILLON (1853–1914) Bertillon devised the first scientific system of personal identification. In 1879, Bertillon began to develop the science of anthropometry (see Chapter 6), a systematic procedure of taking a series of body measurements as a means of distinguishing one individual from another (see Figure 1–3). For nearly two decades, this system was considered

FIGURE 1–2 Sir Arthur Conan Doyle’s legendary detective Sherlock Holmes applied many of the principles of modern forensic science long before they were adopted widely by police.

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FIGURE 1–3 Bertillon’s system of bodily measurements as used for the identification of an individual.

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8 CHAPTER 1

the most accurate method of personal identification. Although anthropometry was eventually replaced by fingerprinting in the early 1900s, Bertillon’s early efforts have earned him the distinction of being known as the father of criminal identification.

FRANCIS GALTON (1822–1911) Galton undertook the first definitive study of fingerprints and developed a methodology of classifying them for filing. In 1892, he published a book titled Finger Prints, which contained the first statistical proof supporting the uniqueness of his method of personal identification. His work went on to describe the basic principles that form the present system of identification by fingerprints.

LEONE LATTES (1887–1954) In 1901, Dr. Karl Landsteiner discovered that blood can be grouped into different categories. These blood groups or types are now recognized as A, B, AB, and O. The possibility that blood grouping could be a useful characteristic for the identification of an individual intrigued Dr. Lattes, a professor at the Institute of Forensic Medicine at the University of Turin in Italy. In 1915, he devised a relatively simple procedure for determining the blood group of a dried bloodstain, a technique that he immediately applied to criminal investigations.

CALVIN GODDARD (1891–1955) To determine whether a particular gun has fired a bullet requires a comparison of the bullet with one that has been test-fired from the suspect’s weapon. Goddard, a U.S. Army colonel, refined the techniques of such an examination by using the comparison microscope. From the mid-1920s on, Goddard’s expertise established the comparison microscope as the indispensable tool of the modern firearms examiner.

ALBERT S. OSBORN (1858–1946) Osborn’s development of the fundamental principles of document examination was responsible for the acceptance of documents as scientific evidence by the courts. In 1910, Osborn authored the first significant text in this field, Questioned Documents. This book is still considered a primary reference for document examiners.

WALTER C. MCCRONE (1916–2002) Dr. McCrone’s career paralleled startling advances in sophisticated analytical technology. Nevertheless, during his lifetime McCrone became the world’s preeminent microscopist. Through his books, journal publications, and research institute, McCrone was a tireless advocate for applying microscopy to analytical problems, particularly forensic science cases. McCrone’s exceptional communication skills made him a much-sought- after instructor, and he was responsible for educating thousands of forensic scientists throughout the world in the application of microscopic techniques. Dr. McCrone used microscopy, often in conjunction with other analytical methodologies, to examine evidence in thousands of criminal and civil cases throughout a long and illustrious career.

HANS GROSS (1847–1915) Gross wrote the first treatise describing the application of scientific disciplines to the field of criminal investigation in 1893. A public prosecutor and judge in Graz, Austria, Gross spent many years studying and developing principles of criminal investigation. In his classic book Handbuch für Untersuchungsrichter als System der Kriminalistik (later published in English under the title Criminal Investigation), he detailed the assistance that investigators could expect from the fields of microscopy, chemistry, physics, mineralogy, zoology, botany, anthropometry, and fingerprinting. He later introduced the forensic journal Archiv für Kriminal Anthropologie und Kriminalistik, which still serves as a medium for reporting improved methods of scientific crime detection.

EDMOND LOCARD (1877–1966) Although Gross was a strong advocate of the use of the scientific method in criminal investigation, he did not make any specific technical contributions to this philosophy. Locard, a Frenchman, demonstrated how the principles enunciated by Gross could be incorporated within a workable crime laboratory. Locard’s formal education was in both medicine and law. In 1910, he persuaded the Lyons police department to give him two attic rooms and two assistants to start a police laboratory.

During Locard’s first years of work, the only available instruments were a microscope and a rudimentary spectrometer. However, his enthusiasm quickly overcame the technical and mon- etary deficiencies he encountered. From these modest beginnings, Locard’s research and accom- plishments became known throughout the world by forensic scientists and criminal investigators.

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Eventually he became the founder and director of the Institute of Criminalistics at the University of Lyons; this quickly developed into a leading international center for study and research in forensic science.

Locard believed that when a person comes in contact with an object or person, a cross- transfer of materials occurs (Locard’s exchange principle). Locard maintained that every criminal can be connected to a crime by dust particles carried from the crime scene. This con- cept was reinforced by a series of successful and well-publicized investigations. In one case, presented with counterfeit coins and the names of three suspects, Locard urged the police to bring the suspects’ clothing to his laboratory. On careful examination, he located small metal- lic particles in all the garments. Chemical analysis revealed that the particles and coins were composed of exactly the same metallic elements. Confronted with this evidence, the suspects were arrested and soon confessed to the crime. After World War I, Locard’s successes served as an impetus for the formation of police laboratories in Vienna, Berlin, Sweden, Finland, and Holland.

Crime Laboratories The most ambitious commitment to forensic science occurred in the United States with the sys- tematic development of national and state crime laboratories. This development greatly hastened the progress of forensic science.

Crime Labs in the United States In 1932, the Federal Bureau of Investigation (FBI), under the directorship of J. Edgar Hoover, organized a national laboratory that offered forensic services to all law enforcement agencies in the country. During its formative stages, agents consulted extensively with business executives, manufacturers, and scientists whose knowledge and experience were useful in guiding the new facility through its infancy. The FBI Laboratory is now the world’s largest forensic laboratory, performing more than one million examinations every year. Its accomplishments have earned it worldwide recognition, and its structure and organization have served as a model for forensic laboratories formed at the state and local levels in the United States as well as in other countries. Furthermore, the opening of the FBI’s Forensic Science Research and Training Center in 1981 gave the United States, for the first time, a facility dedicated to conducting research to develop new and reliable scientific methods that can be applied to forensic science. This facility is also used to train crime laboratory personnel in the latest forensic science techniques and methods.

The oldest forensic laboratory in the United States is that of the Los Angeles Police Department, created in 1923 by August Vollmer, a police chief from Berkeley, California. In the 1930s, Vollmer headed the first U.S. university institute for criminology and criminalistics at the University of California at Berkeley. However, this institute lacked any official status in the university until 1948, when a school of criminology was formed. The famous criminalist Paul Kirk (see Figure 1–4) was selected to head its criminalistics department. Many graduates of this school have gone on to help develop forensic laboratories in other parts of the state and country.

California has numerous federal, state, county, and city crime laborato- ries, many of which operate independently. However, in 1972 the California Department of Justice embarked on an ambitious plan to create a network of state-operated crime laboratories. As a result, California has created a model system of integrated forensic laboratories consisting of regional and satellite facilities. An informal exchange of information and expertise is facilitated among California’s criminalist community through a regional professional society, the California Association of Criminalists. This organization was the forerunner of a number of regional organizations that have developed throughout the United States to foster cooperation among the nation’s growing community of criminalists.

Locard’s exchange principle Whenever two objects come into contact with one another, there is exchange of materials between them.

FIGURE 1–4 Paul Leland Kirk, 1902–1970.

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International Crime Labs In contrast to the American system of independent local laboratories, Great Britain had de- veloped a national system of regional laboratories under the direction of the government’s Home Office. In the early 1990s, the British Home Office reorganized the country’s forensic laboratories into the Forensic Science Service and instituted a system in which police agencies are charged a fee for services rendered by the laboratory. The fee-for-service concept encour- aged the creation of a number of private laboratories that provide services to both police and criminal defense attorneys. One such organization is LGC. In 2010, the British government announced the closure of the Forensic Science Service, citing financial losses. The laboratories closed in 2012, and forensic work in England and Wales is now contracted out to the private sector. Since privatization, LGC has grown to be the largest forensic science provider in the United Kingdom, employing more than seven hundred forensic scientists servicing both police agencies and the private sector.

In Canada, forensic services are provided by three government-funded institutes: (1) six Royal Canadian Mounted Police regional laboratories, (2) the Centre of Forensic Sciences in Toronto, and (3) the Institute of Legal Medicine and Police Science in Montreal. The Royal Canadian Mounted Police opened its first laboratory in Regina, Saskatchewan, in 1937. Alto- gether, more than a hundred countries throughout the world have at least one laboratory facility offering services in the field of forensic science.

Organization of a Crime Laboratory The development of crime laboratories in the United States has been characterized by rapid growth accompanied by a lack of national and regional planning and coordination. It is estimated that more than 411 publicly funded crime laboratories currently operate at vari- ous levels of government (federal, state, county, and municipal)—more than three times the number of crime laboratories operating in 1966. They employ more than 14,000 full-time personnel.

The size and diversity of crime laboratories make it impossible to select any one model that best describes a typical crime laboratory. Although most of these facilities function as part of a police department, others operate under the direction of the prosecutor’s or district attorney’s office; some work with the laboratories of the medical examiner or coroner. Far fewer are af- filiated with universities or exist as independent agencies in government. Laboratory staff sizes range from one person to more than a hundred, and their services may be diverse or specialized, depending on the responsibilities of the agency that houses the laboratory.

The Growth of Crime Laboratories Crime laboratories have mostly been organized by agencies that either foresaw their potential application to criminal investigation or were pressed by the increasing demands of casework. Several reasons explain the unparalleled growth of crime laboratories during the past thirty- five years. Supreme Court decisions in the 1960s were responsible for greater police emphasis on securing scientifically evaluated evidence. The requirement to advise criminal suspects of their constitutional rights and their right of immediate access to counsel has all but eliminated confessions as a routine investigative tool. Successful prosecution of criminal cases requires a thorough and professional police investigation, frequently incorporating the skills of forensic science experts. Modern technology has provided forensic scientists with many new skills and techniques to meet the challenges accompanying their increased participation in the criminal justice system.

Coinciding with changing judicial requirements has been the staggering increase in crime rates in the United States over the past forty years. This factor alone would probably have ac- counted for the increased use of crime laboratory services by police agencies, but only a small percentage of police investigations generate evidence requiring scientific examination. There is, however, one important exception to this observation: drug-related arrests. All illicit-drug seizures must be sent to a forensic laboratory for confirmatory chemical analysis before the case can be adjudicated. Since the mid-1960s, drug abuse has accelerated to nearly uncontrollable

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levels and has resulted in crime laboratories being inundated with drug specimens. Current es- timates indicate that nearly half of all requests for examination of forensic evidence deal with abused drugs.

Future Challenges A more recent impetus leading to the growth and maturation of crime laboratories has been the advent of DNA profiling. Since the early 1990s, this technology has progressed to the point at which traces of blood, semen stains, hair, and saliva residues left behind on stamps, cups, bite marks, and so on have made possible the individualization or near-individualization of biological evidence. To meet the demands of DNA technology, crime labs have expanded staff and in many cases modernized their physical plants. The labor-intensive demands and sophisticated require- ments of the technology have affected the structure of the forensic laboratory as has no other technology in the past fifty years. Likewise, DNA profiling has become the dominant factor in explaining how the general public perceives the workings and capabilities of the modern crime laboratory.

In coming years an estimated ten thousand forensic scientists will be added to the rolls of both public and private forensic laboratories to process crime-scene evidence for DNA and to acquire DNA profiles, as mandated by state laws, from the hundreds of thousands of individuals convicted of crimes. This endeavor has already added many new scientists to the field and will eventually more than double the number of scientists employed by forensic laboratories in the United States.

A major problem facing the forensic DNA community is the substantial backlog of unanalyzed DNA samples from crime scenes. The number of unanalyzed casework DNA samples reported by state and national agencies is more than 57,000. The estimated number of untested convicted offender samples is more than 500,000. In an attempt to eliminate the backlog of convicted offender or arrestee samples to be analyzed and entered into the Combined DNA Index System (CODIS), the federal government has initiated funding for in-house analysis of samples at the crime laboratory or outsourcing samples to private labo- ratories for analysis.

Beginning in 2008, California began collecting DNA samples from all people arrested on sus- picion of a felony, not waiting until a person is convicted. The state’s database, with approximately one million DNA profiles, is already the third largest in the world, behind those maintained by the United Kingdom and the FBI. The federal government plans to begin doing the same.

Types of Crime Laboratories Historically, a federal system of government, combined with a desire to retain local control, has produced a variety of independent laboratories in the United States, precluding the creation of a national system. Crime laboratories to a large extent mirror the fragmented law enforcement structure that exists on the national, state, and local levels.

FEDERAL CRIME LABORATORIES The federal government has no single law enforcement or investigative agency with unlimited jurisdiction. Four major federal crime laboratories have been created to help investigate and enforce criminal laws that extend beyond the jurisdictional boundaries of state and local forces.

The FBI (Department of Justice) maintains the largest crime laboratory in the world. An ultramodern facility housing the FBI’s forensic science services is located in Quantico, Virginia (see Figure 1–5). Its expertise and technology support its broad investigative powers. The Drug Enforcement Administration laboratories (Department of Justice) analyze drugs seized in viola- tion of federal laws regulating the production, sale, and transportation of drugs. The laboratories of the Bureau of Alcohol, Tobacco, Firearms and Explosives (Department of Justice) analyze alcoholic beverages and documents relating to alcohol and firearm excise tax law enforcement and examine weapons, explosive devices, and related evidence to enforce the Gun Control Act of 1968 and the Organized Crime Control Act of 1970. The U.S. Postal Inspection Service main- tains laboratories concerned with criminal investigations relating to the postal service. Each of these federal facilities will offer its expertise to any local agency that requests assistance in rel- evant investigative matters.

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STATE AND LOCAL CRIME LABORATORIES Most state governments maintain a crime laboratory to service state and local law enforcement agencies that do not have ready access to a laboratory. Some states, such as Alabama, California, Illinois, Michigan, New Jersey, Texas, Washington, Oregon, Virginia, and Florida, have developed a comprehensive statewide system of regional or satellite laboratories. These operate under the direction of a central facility and provide forensic services to most areas of the state. The concept of a regional laboratory operating as part of a statewide system has increased the accessibility of many local law enforcement agencies to a crime laboratory, while minimizing duplication of services and ensuring maximum interlaboratory cooperation through the sharing of expertise and equipment.

Local laboratories provide services to county and municipal agencies. Generally, these facilities operate independently of the state crime laboratory and are financed directly by local government. However, as costs have risen, some counties have combined resources and created multicounty laboratories to service their jurisdictions. Many of the larger cities in the United States maintain their own crime laboratories, usually under the direction of the local police department. Frequently, high population and high crime rates combine to make a municipal facility, such as that of New York City, the largest crime laboratory in the state.

Services of the Crime Laboratory Bearing in mind the independent development of crime laboratories in the United States, the wide variation in total services offered in different communities is not surprising. There are many reasons for this, including (1) variations in local laws, (2) the different capabilities and functions of the organization to which a laboratory is attached, and (3) budgetary and staffing limitations.

In recent years, many local crime laboratories have been created solely to process drug specimens. Often these facilities were staffed with few personnel and operated under limited budgets. Although many have expanded their forensic services, some still primarily perform drug analyses. However, even among crime laboratories providing services beyond drug identifica- tion, the diversity and quality of services rendered vary significantly. For the purposes of this text, I have taken the liberty of arbitrarily designating the following units as those that should constitute a “full-service” crime laboratory.

Basic Services Provided by Full-Service Crime Laboratories PHYSICAL SCIENCE UNIT The physical science unit applies principles and techniques of chemistry, physics, and geology to the identification and comparison of crime-scene evidence. It is staffed by criminalists who have the expertise to use chemical tests and modern analytical instrumentation to examine items as diverse as drugs, glass, paint, explosives, and soil. In a laboratory that has a staff large enough to permit specialization, the responsibilities of this unit

FIGURE 1–5 (a) Exterior and (b) interior views of the FBI crime laboratory in Quantico, Virginia.

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may be further subdivided into drug identification, soil and mineral analysis, and examination of a variety of trace physical evidence.

BIOLOGY UNIT The biology unit is staffed with biologists and biochemists who identify and perform DNA profiling on dried bloodstains and other body fluids, compare hairs and fibers, and identify and compare botanical materials such as wood and plants (see Figure 1–6).

FIREARMS UNIT The firearms unit examines firearms, discharged bullets, cartridge cases, shotgun shells, and ammunition of all types. Garments and other objects are also examined to detect firearms discharge residues and to approximate the distance from a target at which a weapon was fired. The basic principles of firearms examination are also applied here to the comparison of marks made by tools (see Figure 1–7).

DOCUMENT EXAMINATION UNIT The document examination unit studies the handwriting and typewriting on questioned documents to ascertain authenticity and/or source. Related responsibilities include analyzing paper and ink and examining indented writings (the term usually applied to the partially visible depressions appearing on a sheet of paper underneath the one on which the visible writing appears), obliterations, erasures, and burned or charred documents.

PHOTOGRAPHY UNIT A complete photographic laboratory examines and records physical evidence. Its procedures may require the use of highly specialized photographic techniques, such as digital imaging, infrared, ultraviolet, and X-ray photography, to make invisible information visible to the naked eye. This unit also prepares photographic exhibits for courtroom presentation.

FIGURE 1–6 A forensic scientist performing DNA analysis.

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FIGURE 1–7 A forensic analyst examining a firearm.

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Optional Services Provided by Full-Service Crime Laboratories TOXICOLOGY UNIT The toxicology group examines body fluids and organs to determine the presence or absence of drugs and poisons. Frequently, such functions are shared with or may be the sole responsibility of a separate laboratory facility placed under the direction of the medical examiner’s or coroner’s office.

In most jurisdictions, field instruments such as the Intoxilyzer are used to determine the al- coholic consumption of individuals. Often the toxicology section also trains operators and main- tains and services these instruments.

LATENT FINGERPRINT UNIT The latent fingerprint unit processes and examines evidence for latent fingerprints when they are submitted in conjunction with other laboratory examinations.

POLYGRAPH UNIT The polygraph, or lie detector, has come to be recognized as an essential tool of the criminal investigator rather than the forensic scientist. However, during the formative years of polygraph technology, many police agencies incorporated this unit into the laboratory’s administrative structure, where it sometimes remains today. In any case, its functions are handled by people trained in the techniques of criminal investigation and interrogation.

VOICEPRINT ANALYSIS UNIT In cases involving telephoned threats or tape-recorded messages, investigators may require the skills of the voiceprint analysis unit to tie the voice to a particular suspect. To this end, a good deal of casework has been performed with the sound spectrograph, an instrument that transforms speech into a visual display called a voiceprint. The validity of this technique as a means of personal identification rests on the premise that the sound patterns produced in speech are unique to the individual and that the voiceprint displays this uniqueness.

CRIME-SCENE INVESTIGATION UNIT The concept of incorporating crime-scene evidence collection into the total forensic science service is slowly gaining recognition in the United States. This unit dispatches specially trained personnel (civilian and/or police) to the crime scene to collect and preserve physical evidence that will later be processed at the crime laboratory.

Whatever the organizational structure of a forensic science laboratory may be, specialization must not impede the overall coordination of services demanded by today’s criminal investigator. Laboratory administrators need to keep open the lines of communication between analysts (civil- ian and uniform), crime-scene investigators, and police personnel. Inevitably, forensic investiga- tions require the skills of many individuals. One notoriously high-profile investigation illustrates this process—the search to uncover the source of the anthrax letters mailed shortly after Septem- ber 11, 2001. Figure 1–8 shows one of the letters and illustrates the multitude of skills required in the investigation—skills possessed by forensic chemists and biologists, fingerprint examiners, and forensic document examiners.

Functions of the Forensic Scientist Although a forensic scientist relies primarily on scientific knowledge and skill, only half of the job is performed in the laboratory. The other half takes place in the courtroom, where the ultimate significance of the evidence is determined. The forensic scientist must not only analyze physical evidence but also persuade a jury to accept the conclusions derived from that analysis.

Analysis of Physical Evidence First and foremost, the forensic scientist must be skilled in applying the principles and tech- niques of the physical and natural sciences to analyze the many types of physical evidence that may be recovered during a criminal investigation. Of the three major avenues available to police investigators for assistance in solving a crime—confessions, eyewitness accounts by victims or witnesses, and the evaluation of physical evidence retrieved from the crime scene—only physical evidence is free of inherent error or bias.

THE IMPORTANCE OF PHYSICAL EVIDENCE Criminal cases are replete with examples of individuals who were incorrectly charged with and convicted of committing a crime because of faulty memories or lapses in judgment. For example, investigators may be led astray during their preliminary evaluation of the events and circumstances surrounding the commission of a

WEBEXTRA 1.1 Take a Tour of a Forensic Laboratory

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Fingerprints may be detectable on paper using a variety of chemical developing techniques (pp. 137–42).

Cellophane tape was used to seal four envelopes containing the anthrax letters. The fitting together of the serrated ends of the tape strips confirmed that they were torn in succession from the same roll of tape (pp. 62–63).

DNA may be recovered from saliva residues on the back of a stamp (p. 397). However, in this case, the stamp is printed onto the envelope.

Ink analysis may reveal a pen’s manufacturer (pp. 451–55).

Paper examination may identify a manufacturer. General appearance, watermarks, fiber analysis, and chemical analysis of pigments, additives, and fillers may reveal a paper's origin (p. 455).

Photocopier toner may reveal its manufacturer through chemical and physical properties (p. 446).Indented writing may be deposited

on paper left underneath a sheet of paper being written upon. Electrostatic imaging is used to visualize indented impressions on paper (p. 450).

Handwriting examination reveals that block lettering is consistent with a single writer who wrote three other anthrax letters (pp. 440–45).

DNA may be recovered from saliva used to seal an envelope (p. 397).

Trace evidence, such as hairs and fibers, may be present within the contents of the envelope.

FIGURE 1–8 An envelope containing anthrax spores along with an anonymous letter was sent to the office of Senator Tom Daschle shortly after the terrorist attacks of September 11, 2001. A variety of forensic skills were used to examine the envelope and letter. Also, bar codes placed on the front and back of the envelope by mail-sorting machines contain address information and information about where the envelope was first processed.

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crime. These errors may be compounded by misleading eyewitness statements and inappropriate confessions. These same concerns don’t apply to physical evidence.

What about physical evidence allows investigators to sort out facts as they are and not what one wishes they were? The hallmark of physical evidence is that it must undergo scientific in- quiry. Science derives its integrity from adherence to strict guidelines that ensure the careful and systematic collection, organization, and analysis of information—a process known as the scientific method. The underlying principles of the scientific method provide a safety net to ensure that the outcome of an investigation is not tainted by human emotion or compromised by distorting, belittling, or ignoring contrary evidence.

The scientific method begins by formulating a question worthy of investigation, such as who committed a particular crime. The investigator next formulates a hypothesis, a reasonable explanation proposed to answer the question. What follows is the basic foundation of scientific inquiry—the testing of the hypothesis through experimentation. The testing process must be thorough and recognized by other scientists as valid. Scientists and investigators must accept the experimental findings even when they wish they were different. Finally, when the hypothesis is validated by experimentation, it becomes suitable as scientific evidence, appropriate for use in a criminal investigation and ultimately available for admission in a court of law.

DETERMINING ADMISSIBILITY OF EVIDENCE In rejecting the scientific validity of the lie detector (polygraph), the District of Columbia Circuit Court in 1923 set forth what has since become a standard guideline for determining the judicial admissibility of scientific examinations. In Frye v. United States,1 the court stated the following:

Just when a scientific principle or discovery crosses the line between the experimental and demonstrable stages is difficult to define. Somewhere in this twilight zone the evidential force of the principle must be recognized, and while the courts will go a long way in admit- ting expert testimony deduced from a well-recognized scientific principle or discovery, the thing from which the deduction is made must be sufficiently established to have gained general acceptance in the particular field in which it belongs.

To meet the Frye standard, the court must decide whether the questioned procedure, tech- nique, or principle is “generally accepted” by a meaningful segment of the relevant scientific com- munity. In practice, this approach required the proponent of a scientific test to present to the court a collection of experts who could testify that the scientific issue before the court is generally ac- cepted by the relevant members of the scientific community. Furthermore, in determining whether a novel technique meets criteria associated with “general acceptance,” courts have frequently taken note of books and papers written on the subject, as well as prior judicial decisions relating to the reliability and general acceptance of the technique. In recent years this approach has en- gendered a great deal of debate as to whether it is sufficiently flexible to deal with new and novel scientific issues that may not have gained widespread support within the scientific community.

OTHER STANDARDS OF ADMISSIBILITY As an alternative to the Frye standard, some courts came to believe that the Federal Rules of Evidence espoused a more flexible standard that did not rely on general acceptance as an absolute prerequisite for admitting scientific evidence. Part of the Federal Rules of Evidence governs the admissibility of all evidence, including expert testimony, in federal courts, and many states have adopted codes similar to those of the Federal Rules. Specifically, Rule 702 of the Federal Rules of Evidence deals with the admissibility of expert testimony:

If scientific, technical, or other specialized knowledge will assist the trier of fact to un- derstand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education, may testify thereto in the form of an opinion or otherwise, if (1) the testimony is based upon sufficient facts or data, (2) the testimony is the product of reliable principles and methods, and (3) the witness has applied the principles and methods reliably to the facts of the case.

In a landmark ruling in the 1993 case of Daubert v. Merrell Dow Pharmaceuticals, Inc.,2 the U.S. Supreme Court asserted that “general acceptance,” or the Frye standard, is not an abso- lute prerequisite to the admissibility of scientific evidence under the Federal Rules of Evidence.

scientific method A process that uses strict guidelines to ensure careful and systematic collection, organization, and analysis of information.

1 293 Fed. 1013 (D.C. Cir. 1923). 2 509 U.S. 579 (1993).

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INTRODUCTION 17

According to the Court, the Rules of Evidence—especially Rule 702—assign to the trial judge the task of ensuring that an expert’s testimony rests on a reliable foundation and is relevant to the case. Although this ruling applies only to federal courts, many state courts are expected to use this decision as a guideline in setting standards for the admissibility of scientific evidence.

JUDGING SCIENTIFIC EVIDENCE What the Court advocates in Daubert is that trial judges assume the ultimate responsibility for acting as a “gatekeeper” in judging the admissibility and reliability of scientific evidence presented in their courts (see Figure 1–9). The Court offered some guidelines as to how a judge can gauge the veracity of scientific evidence, emphasizing that the inquiry should be flexible. Suggested areas of inquiry include the following:

1. Whether the scientific technique or theory can be (and has been) tested 2. Whether the technique or theory has been subject to peer review and publication 3. The technique’s potential rate of error 4. Existence and maintenance of standards controlling the technique’s operation 5. Whether the scientific theory or method has attracted widespread acceptance within a rel-

evant scientific community

Some legal practitioners have expressed concern that abandoning Frye’s general-acceptance test will result in the introduction of absurd and irrational pseudoscientific claims in the court- room. The Supreme Court rejected these concerns:

In this regard the respondent seems to us to be overly pessimistic about the capabilities of the jury and of the adversary system generally. Vigorous cross-examination, presentation of contrary evidence, and careful instruction on the burden of proof are the traditional and appropriate means of attacking shaky but admissible evidence.

In a 1999 decision, Kumho Tire Co., Ltd. v. Carmichael,3 the Court unanimously ruled that the “gatekeeping” role of the trial judge applied not only to scientific testimony, but to all expert testimony:

We conclude that Daubert’s general holding—setting forth the trial judge’s general “gate- keeping” obligation—applies not only to testimony based on “scientific” knowledge, but also to testimony based on “technical” and “other specialized” knowledge. . . . We also conclude

FIGURE 1–9 Sketch of a U.S. Supreme Court hearing.

3 526 U.S. 137 (1999).

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that a trial court may consider one or more of the more specific factors that Daubert men- tioned when doing so will help determine that testimony’s reliability. But, as the Court stated in Daubert, the test of reliability is “flexible,” and Daubert’s list of specific factors neither necessarily nor exclusively applies to all experts in every case.

A leading case that exemplifies the type of flexibility and wide discretion that the Daubert ruling apparently gives trial judges in matters of scientific inquiry is Coppolino v. State.4 Here a medical examiner testified to his finding that the victim had died of an overdose of a drug known as succinylcholine chloride. This drug had never before been detected in the human body. The medical examiner’s findings were dependent on a toxicological report that identified an abnor- mally high concentration of succinic acid, a breakdown product of the drug, in the victim’s body. The defense argued that this test for the presence of succinylcholine chloride was new and the absence of corroborative experimental data by other scientists meant that it had not yet gained general acceptance in the toxicology profession. The court, in rejecting this argument, recog- nized the necessity for devising new scientific tests to solve the special problems that are continu- ally arising in the forensic laboratory. It emphasized, however, that although these tests may be new and unique, they are admissible only if they are based on scientifically valid principles and techniques: “The tests by which the medical examiner sought to determine whether death was caused by succinylcholine chloride were novel and devised specifically for this case. This does not render the evidence inadmissible. Society need not tolerate homicide until there develops a body of medical literature about some particular lethal agent.”

4 223 So. 2d 68 (Fla. App. 1968), app. dismissed, 234 So. 2d (Fla. 1969), cert. denied, 399 U.S. 927 (1970).

Dr. Coppolino’s Deadly House Calls A frantic late-night telephone call brought a local physician to the Florida home of Drs. Carl and Carmela Coppolino. The physician arrived to find Carmela beyond help. Carmela Coppolino’s body, unexamined by anyone, was then buried in her family’s plot in her home state of New Jersey.

A little more than a month later, Carl married a moneyed so- cialite, Mary Gibson. News of Carl’s marriage infuriated Mar- jorie Farber, a former New Jersey neighbor of Dr. Coppolino who had been a having an affair with the good doctor. Soon Marjorie had an interesting story to recount to investigators: Her husband’s death two years before, although ruled to be from natural causes, had actually been murder! Carl, an anesthesiologist, had given Marjorie a syringe containing some medication and told her to inject her husband, William, while he was sleeping. Ultimately, Marjorie claimed, she was unable to inject the full dose and called Carl, who finished the job by suffocating William with a pillow.

Marjorie Farber’s astonishing story was supported in part by Carl’s having recently increased his wife’s life insurance. Car- mela’s $65,000 policy, along with his new wife’s fortune, would keep Dr. Coppolino in high society for the rest of his life. Based on this information, authorities in New Jersey and Florida ob- tained exhumation orders for both William Farber and Carmela Coppolino. After both bodies were examined, Dr. Coppolino was charged with the murders of William and Carmela.

Officials decided to try Dr. Coppolino first in New Jersey for the murder of William Farber. The Farber autopsy did not reveal any evidence of poisoning but seemed to show strong evidence of strangulation. The absence of toxicologi- cal findings left the jury to deliberate the conflicting medi- cal expert testimony versus the sensational story told by a scorned and embittered woman. In the end, Dr. Coppolino was acquitted.

The Florida trial presented another chance to bring Carl Coppolino to justice. Recalling Dr. Coppolino’s career as an anesthesiologist, the prosecution theorized that to commit these murders Coppolino had exploited his access to the many potent drugs used during surgery, specifically an injectable paralytic agent called succinylcholine chloride.

Carmela’s body was exhumed, and it was found that Carmela had been injected in her left buttock shortly be- fore her death. Ultimately, a completely novel procedure for detecting succinylcholine chloride was devised. With this pro- cedure elevated levels of succinic acid were found in Carmela’s brain, which proved that she had received a large dose of the paralytic drug shortly before her death. This evidence, along with evidence of the same drug residues in the injection site on her buttock, was presented in the Florida murder trial of Carl Coppolino, who was convicted of second-degree murder.

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Providing Expert Testimony Because the results of their work may be a factor in determining a person’s ultimate guilt or innocence, forensic scientists may be required to testify about their methods and conclusions at a trial or hearing.

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Trial courts have broad discretion in accepting an individual as an expert witness on any particular subject. Generally, if a witness can establish to the satisfaction of a trial judge that he or she possesses a particular skill or has knowledge in a trade or profession that will aid the court in determining the truth of the matter at issue, that individual will be accepted as an expert witness. Depending on the subject area in question, the court will usually consider knowledge acquired through experience, training, education, or a combination of these as sufficient grounds for qualification as an expert witness.

In court, an expert witness may be asked questions intended to demonstrate his or her ability and competence pertaining to the matter at hand. Competency may be established by having the witness cite educational degrees, participation in special courses, membership in professional societies, and any professional articles or books published. Also important is the number of years of occupational experience the witness has had in areas related to the matter before the court.

Most chemists, biologists, geologists, and physicists prepare themselves for careers in fo- rensic science by combining training under an experienced examiner with independent study. Of course, formal education in the physical sciences provides a firm foundation for learning and understanding the principles and techniques of forensic science. Nevertheless, for the most part, courts must rely on training and years of experience as a measurement of the knowledge and ability of the expert.

Before the judge rules on the witness’s qualifications, the opposing attorney may cross- examine the witness and point out weaknesses in training and knowledge. Most courts are reluctant to disqualify an individual as an expert even when presented with someone whose background is only remotely associated with the issue at hand. The question of what credentials are suitable for qualification as an expert is ambiguous and highly subjective and one that the courts wisely try to avoid.

The weight that a judge or jury assigns to “expert” testimony in subsequent deliberations is, however, quite another matter. Undoubtedly, education and experience have considerable bear- ing on what value should be assigned to the expert’s opinions. Just as important may be his or her demeanor and ability to explain scientific data and conclusions clearly, concisely, and logi- cally to a judge and jury composed of nonscientists. The problem of sorting out the strengths and weaknesses of expert testimony falls to prosecution and defense counsel.

The ordinary or lay witness must testify on events or observations that arise from personal knowledge. This testimony must be factual and, with few exceptions, cannot contain the personal opinions of the witness. On the other hand, the expert witness is called on to evaluate evidence when the court lacks the expertise to do so. This expert then expresses an opinion as to the signifi- cance of the findings. The views expressed are accepted only as representing the expert’s opinion and may later be accepted or ignored in jury deliberations (see Figure 1–10).

The expert cannot render any view with absolute certainty. At best, he or she may only be able to offer an opinion based on a reasonable scientific certainty derived from training and ex- perience. Obviously, the expert is expected to defend vigorously the techniques and conclusions of the analysis, but at the same time he or she must not be reluctant to discuss impartially any findings that could minimize the significance of the analysis. The forensic scientist should not be an advocate of one party’s cause but an advocate of truth only. An adversary system of justice must give the prosecutor and defense ample opportunity to offer expert opinions and to argue the merits of such testimony. Ultimately, the duty of the judge or jury is to weigh the pros and cons of all the information presented when deciding guilt or innocence.

The necessity for the forensic scientist to appear in court has been imposed on the crimi- nal justice system by a 2009 U.S. Supreme Court Case, Melendez-Diaz v. Massachusetts.5 The Melendez-Diaz decision addressed the practice of using evidence affidavits or laboratory certifi- cates in lieu of in-person testimony by forensic analysts. In its reasoning, the Court relied on a previous ruling, Crawford v. Washington,6 where it explored the meaning of the Confrontation Clause of the Sixth Amendment. In the Crawford case, a recorded statement by a spouse was used against her husband in his prosecution. Crawford argued that this was a violation of his right to confront witnesses against him under the Sixth Amendment, and the Court agreed. Using the same logic in Melendez-Diaz , the Court reasoned that introducing forensic science evidence via

expert witness An individual whom the court determines to possess knowledge relevant to the trial that is not expected of the average layperson.

5 557 U.S. 305 (2009). 6 541 U.S. 36 (2004).

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an affidavit or a certificate denied a defendant the opportunity to cross-examine the analyst. In 2011, the Supreme Court reaffirmed the Melendez-Diaz decision in the case of Bullcoming v. New Mexico7 by rejecting a substitute expert witness in lieu of the original analyst:

The question presented is whether the Confrontation Clause permits the prosecution to introduce a forensic laboratory report containing a testimonial certification—made for the purpose of proving a particular fact through the in-court testimony of a scientist who did not sign the certification or perform or observe the test reported in the certification. We hold that surrogate testimony of that order does not meet the constitutional requirement. The accused’s right is to be confronted with the analyst who made the certification, unless that analyst is unavailable at trial, and the accused had an opportunity, pretrial, to cross- examine that particular scientist.

Furnishing Training in the Proper Recognition, Collection, and Preservation of Physical Evidence The competence of a laboratory staff and the sophistication of its analytical equipment have little or no value if relevant evidence cannot be properly recognized, collected, and preserved at the site of a crime. For this reason, the forensic staff must have responsibilities that will influence the conduct of the crime-scene investigation.

The most direct and effective response to this problem has been to dispatch specially trained evidence-collection technicians to the crime scene. A growing number of crime laboratories and the police agencies they service keep trained “evidence technicians” on 24-hour call to help criminal investigators retrieve evidence. These technicians are trained by the laboratory staff to recognize and gather pertinent physical evidence at the crime scene. They are assigned to the laboratory full time for continued exposure to forensic techniques and procedures. They have at their disposal all the proper tools and supplies for proper collection and packaging of evidence for future scientific examination.

Unfortunately, many police forces still have not adopted this approach. Often a patrol officer or detective collects the evidence. The individual’s effectiveness in this role depends on the ex- tent of his or her training and working relationship with the laboratory. For maximum use of the skills of the crime laboratory, training of the crime-scene investigator must go beyond superficial

7 131 S. Ct. 2705 (2011).

WEBEXTRA 1.2 Watch a Forensic Expert Witness Testify—I

WEBEXTRA 1.3 Watch a Forensic Expert Witness Testify—II

FIGURE 1–10 An expert witness testifying in court.

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INTRODUCTION 21

classroom lectures to involve extensive personal contact with the forensic scientist. Each must become aware of the other’s problems, techniques, and limitations.

The training of police officers in evidence collection and their familiarization with the ca- pabilities of a crime laboratory should not be restricted to a select group of personnel on the force. Every officer engaged in fieldwork, whether it be traffic, patrol, investigation, or juvenile control, often must process evidence for laboratory examination. Obviously, it would be difficult and time consuming to give everyone the in-depth training and attention that a qualified criminal investigator requires. However, familiarity with crime laboratory services and capabilities can be gained through periodic lectures, laboratory tours, and dissemination of manuals prepared by the laboratory staff that outline the proper methods for collecting and submitting physical evidence to the laboratory (see Figure 1–11).

A brief outline describing the proper collection and packaging of common types of physical evidence is found in Appendix I. The procedures and information summarized in this appendix are discussed in greater detail in forthcoming chapters.

Other Forensic Science Services Even though this textbook is devoted to describing the services normally provided by a crime laboratory, the field of forensic science is by no means limited to the areas covered in this book. A number of specialized forensic science services outside the crime laboratory are routinely available to law enforcement personnel. These services are important aids to a criminal investiga- tion and require the involvement of individuals who have highly specialized skills.

Forensic Psychiatry Forensic psychiatry is a specialized area in which the relationship between human behavior and legal proceedings is examined. Forensic psychiatrists are retained for both civil and criminal liti- gations. For civil cases, forensic psychiatrists normally determine whether people are competent to make decisions about preparing wills, settling property, or refusing medical treatment. For criminal cases, they evaluate behavioral disorders and determine whether people are competent to stand trial. Forensic psychiatrists also examine behavioral patterns of criminals as an aid in developing a suspect’s behavioral profile.

FIGURE 1–11 Representative evidence-collection guides prepared by various police agencies.

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Forensic Odontology Practitioners of forensic odontology help identify victims when the body is left in an unrec- ognizable state. Teeth are composed of enamel, the hardest substance in the body. Because of enamel’s resilience, the teeth outlast tissues and organs as decomposition begins. The char- acteristics of teeth, their alignment, and the overall structure of the mouth provide individual evidence for identifying a specific person. With the use of dental records such as X-rays and dental casts or even a photograph of the person’s smile, a set of dental remains can be com- pared to a suspected victim. Another application of forensic odontology to criminal inves- tigations is bite mark analysis. At times in assault cases, bite marks are left on the victim. A forensic odontologist can compare the marks left on a victim and the tooth structure of the suspect (see Figure 1–12).

Forensic Engineering Forensic engineers are concerned with failure analysis, accident reconstruction, and causes and origins of fires or explosions. Forensic engineers answer questions such as these: How did an accident or structural failure occur? Were the parties involved responsible? If so, how were they responsible? Accident scenes are examined, photographs are reviewed, and any mechanical objects involved are inspected.

Forensic Computer and Digital Analysis Forensic computer science is a new and fast-growing field that involves the identification, collec- tion, preservation, and examination of information derived from computers and other digital de- vices, such as cell phones. Law enforcement aspects of this work normally involve the recovery of deleted or overwritten data from a computer’s hard drive and the tracking of hacking activities within a compromised system. This field of forensic computer analysis and recovery of data from mobile devices will be addressed in detail in Chapters 18 and 19.

FIGURE 1–12 (a) Bite mark on victim’s body. (b) Comparison to suspect’s teeth.

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INTRODUCTION 23

Exploring Forensic Science on the Internet There are no limits to the amount or type of information that can be found on the Internet. The fields of law enforcement and forensic science have not been left behind by advancing computer technology. Extensive information about forensic science is available on the Internet. The types of information available on websites range from simple explanations of the various fields of forensics to intricate details of crime-scene reconstruction. People can also find information on which colleges offer degree programs in forensics and web pages posted by law enforcement agencies that detail their activities as well as employment opportunities.

General Forensics Sites Reddy’s Forensic Home Page (www.forensicpage.com) is a valuable starting point. This site is a collection of forensic web pages in categories such as new links in forensics; general forensic information sources; associations, colleges, and societies; literature and journals; forensic labo- ratories; general web pages; forensic-related mailing lists and newsgroups; universities; confer- ences; and various forensic fields of expertise.

Another website offering a multitude of information related to forensic science is Zeno’s Forensic Site (www.forensic.to/forensic.html). Here users can find links related to forensic edu- cation and expert consultation, as well as a wealth of information concerning specific fields of forensic science.

A comprehensive and useful website for those interested in law enforcement is Officer.com (www.officer.com). This comprehensive collection of criminal justice resources is organized into easy-to-read subdirectories that relate to topics such as law enforcement agencies, police association and organization sites, criminal justice organizations, law research pages, and police mailing-list directories.

AN INTRODUCTION TO FORENSIC FIREARM IDENTIFICATION (http://www.firearmsid .com/) This website contains an extensive collection of information relating to the identification of firearms. An individual can explore in detail how to examine bullets, cartridge cases, and clothing for gunshot residues and suspect shooters’ hands for primer residues. Information on the latest technology involving the automated firearms search system NIBIN can also be found on this site.

CARPENTER’S FORENSIC SCIENCE RESOURCES (http://www.tncrimlaw.com/forensic/) This site provides a bibliography involving forensic evidence. For example, the user can find references about DNA, fingerprints, hairs, fibers, and questioned documents as they relate to crime scenes and assist investigations. This website is an excellent place to start a research project in forensic science.

CRIME SCENE INVESTIGATOR NETWORK (http://www.crime-scene-investigator.net/index .html) For those who are interested in learning the process of crime-scene investigation, this site provides detailed guidelines and information regarding crime-scene response and the collection and preservation of evidence. For example, information concerning the packaging and analysis of bloodstains, seminal fluids, hairs, fibers, paint, glass, firearms, documents, and fingerprints can be found through this website. It explains the importance of inspecting the crime scene and the impact forensic evidence has on the investigation.

CRIMES AND CLUES (http://crimeandclues.com/) Users interested in learning about the forensic aspects of fingerprinting will find this to be a useful and informative website. The site covers the history of fingerprints, as well as subjects pertaining to the development of latent fingerprints. The user will also find links to other websites covering a variety of subjects pertaining to crime- scene investigation, documentation of the crime scene, and expert testimony.

QUESTIONED-DOCUMENT EXAMINATION (http://www.qdewill.com/) This basic, informative web page answers frequently asked questions concerning document examination, explains the application of typical document examinations, and details the basic facts and theory of handwriting and signatures. There are also links to noted document examination cases that present the user with real-life applications of forensic document examination.

WEBEXTRA 1.4 An Introduction to Forensic Firearm Identification

WEBEXTRA 1.5 Carpenter’s Forensic Science Resources

WEBEXTRA 1.6 Crime Scene Investigator Network

WEBEXTRA 1.7 Crimes and Clues

WEBEXTRA 1.8 Questioned-Document Examination

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In its broadest definition, forensic science is the application of science to criminal and civil laws. This book emphasizes the ap- plication of science to the criminal and civil laws that are enforced by police agencies in a criminal justice system. Forensic science owes its origins to individuals such as Bertillon, Galton, Lattes, Goddard, Osborn, and Locard, who developed the principles and techniques needed to identify or compare physical evidence.

The development of crime laboratories in the United States has been characterized by rapid growth accompanied by a lack of national and regional planning and coordination. At present, ap- proximately four hundred public crime laboratories operate at var- ious levels of government—federal, state, county, and municipal.

The technical support provided by crime laboratories can be assigned to five basic services. The physical science unit uses the principles of chemistry, physics, and geology to identify and compare physical evidence. The biology unit uses knowledge of biological sciences to investigate blood samples, body fluids, hair, and fiber samples. The firearms unit inves- tigates discharged bullets, cartridge cases, shotgun shells, and ammunition. The document examination unit performs hand- writing analysis and other questioned-document examination. Finally, the photography unit uses specialized photographic techniques to record and examine physical evidence. Some crime laboratories offer the optional services of toxicology, fingerprint analysis, polygraph administration, voiceprint anal- ysis, and crime-scene investigation and evidence collection.

A forensic scientist must be skilled in applying the princi- ples and techniques of the physical and natural sciences to the analysis of the many types of evidence that may be recovered during a criminal investigation. A forensic scientist may also provide expert court testimony. An expert witness is called on to evaluate evidence based on specialized training and experi- ence and to express an opinion as to the significance of the findings. Also, forensic scientists participate in training law enforcement personnel in proper recognition, collection, and preservation of physical evidence.

The Frye v. United States decision set guidelines for determining the admissibility of scientific evidence into the courtroom. To meet the Frye standard, the evidence in ques- tion must be “generally accepted” by the scientific commu- nity. However, in the 1993 case of Daubert v. Merrell Dow Pharmaceuticals, Inc., the U.S. Supreme Court asserted that the Frye standard is not an absolute prerequisite to the ad- missibility of scientific evidence. Trial judges were said to be ultimately responsible as “gatekeepers” for the admissibility and validity of scientific evidence presented in their courts.

A number of special forensic science services are avail- able to the law enforcement community to augment the ser- vices of the crime laboratory. These services include forensic psychiatry, forensic odontology, forensic engineering, and forensic computer and digital analysis.

chapter summary

review questions

1. The application of science to law describes ___________.

2. The fictional exploits of ___________ excited the imagination of an emerging generation of forensic sci- entists and criminal investigators.

3. A system of personal identification using a series of body measurements was first devised by ___________.

4. ___________ is responsible for developing the first statistical study proving the uniqueness of fingerprints.

5. The Italian scientist ___________ devised the first workable procedure for typing dried bloodstains.

6. The comparison microscope became an indispensable tool of firearms examination through the efforts of ___________.

7. Early efforts at applying scientific principles to docu- ment examination are associated with ___________.

8. The application of science to criminal investigation was advocated by the Austrian magistrate ___________.

9. One of the first functional crime laboratories was formed in Lyons, France, under the direction of ___________.

10. The transfer of evidence that occurs when two objects come in contact with one another was a concept first advocated by the forensic scientist ___________.

11. The first forensic laboratory in the United States was created in 1923 by the ___________ Police Department.

12. The state of ___________ is an excellent example of a geographical area in the United States that has created a system of integrated regional and satellite laboratories.

13. In contrast to the United States, Britain’s crime labo- ratory system is characterized by a national system of ___________ laboratories.

14. The increasing demand for ___________ analyses has been the single most important factor in the recent ex- pansion of crime laboratory services in the United States.

15. Four important federal agencies offering forensic ser- vices are ___________, ___________, ___________, and ___________.

16. A decentralized system of crime laboratories cur- rently exists in the United States under the auspices of various governmental agencies at the ___________, ___________, ___________, and ___________ levels of government.

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17. The application of chemistry, physics, and geology to the identification and comparison of crime-scene evi- dence is the function of the ___________ unit of a crime laboratory.

18. The examination of blood, hairs, fibers, and botanical materials is conducted in the ___________ unit of a crime laboratory.

19. The examination of bullets, cartridge cases, shotgun shells, and ammunition of all types is the responsibility of the ___________ unit.

20. The examination of body fluids and organs for drugs and poisons is a function of the ___________ unit.

21. The ___________ unit dispatches trained personnel to the scene of a crime to retrieve evidence for laboratory examination.

22. The “general acceptance” principle, which serves as a criterion for the judicial admissibility of scientific evi- dence, was set forth in the case of ___________.

23. In the case of ___________, the Supreme Court ruled that in assessing the admissibility of new and unique sci- entific tests, the trial judge did not have to rely solely on the concept of “general acceptance.”

24. True or False: The U.S. Supreme Court decision in Kumho Tire Co., Ltd. v. Carmichael restricted the

“gatekeeping” role of a trial judge only to scientific tes- timony. ___________

25. A Florida case that exemplifies the flexibility and wide discretion that the trial judge has in matters of scientific inquiry is ___________.

26. A(n) ___________ is a person who can demonstrate a par- ticular skill or has knowledge in a trade or profession that will help the court determine the truth of the matter at issue.

27. True or False: The expert witness’s courtroom demeanor may play an important role in deciding what weight the court will assign to his or her testimony. ___________

28. True or False: The testimony of an expert witness incor- porates his or her personal opinion relating to a matter he or she has either studied or examined. ___________

29. The ability of the investigator to recognize and collect crime-scene evidence properly depends on the amount of ___________ received from the crime laboratory.

30. True or False: In 2004, the U.S. Supreme Court ad- dressed issues relating to the Confrontation Clause of the Sixth Amendment in the case of Crawford v. Washington. ___________

31. The 2009 U.S. Supreme Court decision ___________ addressed the practice of using affidavits in lieu of in- person testimony by forensic examiners.

1. Most crime labs in the United States are funded and operated by the government and provide services free to police and prosecutors. Great Britain, however, uses private laboratories that charges fees for their services and keep any profits they make. Suggest potential strengths and weaknesses of each system.

2. Police investigating an apparent suicide collect the following items at the scene: a note purportedly writ- ten by the victim, a revolver bearing very faint finger- prints, and traces of skin and blood under the victim’s fingernails. What units of the crime laboratory will examine each piece of evidence?

3. List at least three advantages of having an evidence- collection unit process a crime scene instead of a pa- trol officer or detective.

4. What legal issue was raised on appeal by the defense in Carl Coppolino’s Florida murder trial? What court ruling is most relevant to the decision to reject the ap- peal? Explain your answer.

5. A Timeline of Forensic Science The following images depict different types of evidence or techniques for ana- lyzing evidence. Place the images in order pertaining to the time in history (least recent to most recent) at which each type of evidence or technique was first introduced. Do this using the letters assigned to the images.

application and critical thinking

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26 CHAPTER 1

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6. Evidence Processing at the Crime Laboratory You are the evidence technician at the front desk of the state crime lab. You receive the following items of evidence to check in on a very busy day. You must indicate which unit each piece of evidence should be sent to for analysis. Your crime lab has a criminalistics (physical science) unit, a drug unit, a biology unit, a firearms unit, a document ex- amination unit, a toxicology unit, a latent fingerprinting unit, an anthropology unit, and a forensic computer and digital analysis unit.

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further references

Sandercock, P. Mark L., “75 Years of Forensic Chemis- try in the Royal Canadian Mounted Police. A Timeline for Trace Evidence, 1937–2012,” Canadian Society of Forensic Science Journal 46 (2013): 120.

Sapir, Gil I., “Legal Aspects of Forensic Science,” in R. Saferstein, ed., Forensic Science Handbook, vol. 1, 2nd ed. Upper Saddle River, N.J.: Prentice Hall, 2002.

Shelton, D. E., “The CSI Effect: Does It Really Exist?” http://www.nij.gov/journals/259/csi-effect.htm

Starrs, James E., “Mountebanks among Forensic Scientists,” in R. Saferstein, ed., Forensic Science Handbook, vol. 2, 2nd ed. Upper Saddle River, N.J.: Prentice Hall, 2005.

Waggoner, Kim, “The FBI Laboratory: 75 Years of Forensic Science Service,” Forensic Science Communications 9, no. 4 (2007). http://www.fbi.gov/ about-us/lab/forensic-science-communications/fsc/ oct2007

A Simplified Guide to Forensic Science http://www .forensicsciencesimplified.org/

Cohen, Stanley A., “The Role of the Forensic Expert in a Criminal Trial,” Canadian Society of Forensic Science Journal 12 (1979): 75.

Doyle, Sir Arthur Conan, The Complete Sherlock Holmes, vol. 1. New York: Doubleday, 1956.

Kagan, J. D., “On Being a Good Expert Witness in a Criminal Case,” Journal of Forensic Sciences 23 (1978): 190.

Lucas, D. M., “North of 49—The Development of Forensic Science in Canada,” Science & Justice 37 (1997): 47.

Midkiff, C. R., “More Mountebanks,” in R. Saferstein, ed., Forensic Science Handbook, vol. 2, 2nd ed. Upper Saddle River, N.J.: Prentice Hall, 2005.

National Research Council, Strengthening Forensic Science in the United States: A Path Forward, Washington, D.C.: National Academies Press, 2009, http://books.nap.edu/ openbook.php?record_id=12589&page=R1

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JonBenét Ramsey: Who Did It?

Patsy Ramsey awoke just after five a.m. on December 26, 1996, and walked downstairs to her kitchen. At the foot of the staircase, she found a two-and-a-half-page note saying that her 6-year-old daughter, JonBenét, had been kidnapped. The note contained a ransom demand of $118,000. Patsy and John Ramsey were in the upper crust of Boulder, Colorado, society. In the span of five short years, John had built his computer company into a billion-dollar corporation. When the police arrived to investigate, it was quite apparent to all that JonBenét was missing. In retrospect, some serious mistakes were made in securing

the crime scene—the Ramsey household. Initially, the police conducted a cursory search of the house but failed to find

JonBenét. The house was not sealed off; in fact, four friends along with the Ramsey pastor were let into the home and allowed to move about at will. John was permitted to leave

the premises unattended for one and a half hours. One hour after his return, John and two of his friends searched the house again. This time John went down into the basement, where he discovered JonBenét’s body. He removed a white blanket from JonBenét and carried her upstairs, placing the body on the living room floor.

The murder of JonBenét Ramsey remains as baffling a mystery today as it was on its first day. Ample physical evidence exists to support the theory that the crime was committed by an outsider, and also that JonBenét was murdered by someone who resided in the Ramsey household. Twelve years after the commission of the crime, Boulder district attorney Mary T. Lacy issued a statement exonerating members of the Ramsey family on the basis of DNA evidence. Perhaps better care in securing and processing the crime scene could have resolved some of the crime’s outstanding questions. A more detailed analysis of this crime can be found on pages 399–401.

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After studying this chapter you should be able to: Define physical evidence

Discuss the responsibilities of the first police officer who arrives at a crime scene

Explain the steps to be taken to thoroughly record the crime scene

Describe proper procedures for conducting a systematic search of a crime scene for physical evidence

Describe proper techniques for packaging common types of physical evidence

Define and understand the concept of chain of custody

Relate what steps are typically required to maintain appropriate health and safety standards at the crime scene

Understand the implications of the Mincey and Tyler cases

the crime scene

buccal swab chain of custody finished sketch physical evidence rough sketch standard/reference

sample substrate control

KEY TERMS

chapter 2

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30 CHAPTER 2

Processing the Crime Scene As automobiles run on gasoline, crime laboratories “run” on physical evidence. Physical evi- dence encompasses any and all objects that can establish that a crime has or has not been com- mitted or can link a crime and its victim or its perpetrator. But if physical evidence is to be used effectively to aid the investigator, its presence first must be recognized at the crime scene. If all the natural and commercial objects within a reasonable distance of a crime were gathered so that the scientist could uncover significant clues from them, the deluge of material would quickly immobilize the laboratory facility. Physical evidence can achieve its optimum value in criminal investigations only when its collection is performed with a selectivity governed by the collector’s thorough knowledge of the crime laboratory’s techniques, capabilities, and limitations.

Forthcoming chapters will be devoted to discussions of methods and techniques available to forensic scientists to evaluate physical evidence. Although current technology has given the crime laboratory capabilities far exceeding those of past decades, these advances are no excuse for complacency on the part of criminal investigators. Crime laboratories do not solve crimes; only a thorough and competent investigation conducted by professional police officers will en- hance the chances for a successful criminal investigation. Forensic science is, and will continue to be, an important element of the total investigative process, but it is only one aspect of an endeavor that must be a team effort. The investigator who believes the crime laboratory to be a panacea for laxity or ineptness is in for a rude awakening.

Forensic science begins at the crime scene. If the investigator cannot recognize physical evidence or cannot properly preserve it for laboratory examination, no amount of sophisticated laboratory instrumentation or technical expertise can salvage the situation. The know-how for conducting a proper crime-scene search for physical evidence is within the grasp of any police department, regardless of its size. With proper training, police agencies can ensure competent performance at crime scenes. In many jurisdictions, police agencies have delegated this task to a specialized team of technicians. However, the techniques of crime-scene investigation are not dif- ficult to master and certainly lie within the bounds of comprehension of the average police officer.

Not all crime scenes require retrieval of physical evidence, and limited resources and per- sonnel have forced many police agencies to restrict their efforts in this area to crimes of a more serious nature. Once the commitment is made to completely process a crime site for physical evidence, however, certain fundamental practices must be followed.

Securing and Isolating the Crime Scene The first officer arriving on the scene of a crime is responsible for preserving and protecting the area as much as possible. The officer should not let his or her guard down and must rely on his or her training to deal with any violent or hazardous circumstances. Special note should be taken of any vehicles or people leaving the scene.

Of course, first priority should be given to obtaining medical assistance for individuals in need of it and to arresting the perpetrator. However, as soon as possible, extensive efforts must be made to exclude all unauthorized personnel from the scene. If medical assistance is needed, the of- ficer should direct medical workers to approach the body by an indirect route to minimize the pos- sibility of disturbing evidence. The first responding officer must evaluate the victim’s condition and record any statements made by the victim. This information should later be included in notes.

As additional officers arrive, measures are immediately initiated to isolate the area (see Figure 2–1). The boundaries should encompass the center of the scene where the crime occurred, any paths of entry or exit, and any areas where evidence may have been discarded or moved. Ropes or barricades along with strategic positioning of guards will prevent unauthorized access to the area. Efforts must be taken to identify all individuals at the scene and detain all potential suspects or witnesses still at the scene. At the same time, officers should exclude all unauthorized personnel from the scene. This includes family and friends of the victim, who should be shown as much compassion as possible. Only investigative personnel assigned to the scene should be admitted. The responding officers must keep an accurate log of who enters and exits the scene and the time at which they do so.

Sometimes the exclusion of unauthorized personnel proves more difficult than expected. Violent crimes are especially susceptible to attention from higher-level police officials and mem- bers of the press, as well as by emotionally charged neighbors and curiosity seekers. Every

physical evidence Any object that can establish that a crime has or has not been com- mitted or can link a crime and its victim or its perpetrator.

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individual who enters the scene is a potential destroyer of physical evidence, even if it is by unintentional carelessness. To exercise proper control over the crime scene, the officer respon- sible for protecting it must have the authority to exclude everyone, including fellow police of- ficers not directly involved in processing the site or in conducting the investigation. Seasoned criminal investigators are always prepared to relate horror stories about crime scenes where physical evidence was rendered totally valueless by hordes of people who, for one reason or another, trampled through the site. Securing and isolating the crime scene are critical steps in an investigation, the accomplishment of which is the mark of a trained and professional crime-scene investigative team.

Once the scene has been secured, a lead investigator starts evaluating the area. First, he or she determines the boundaries of the scene and then establishes the perpetrator’s path of entry and exit. Logic dictates that obvious items of crime-scene evidence will first come to the at- tention of the crime-scene investigator. These items must be documented and photographed. The investigator then proceeds with an initial walk-through of the scene to gain an overview of the situation and develop a strategy for systematically examining and documenting the entire crime scene.

Personnel should never do anything while at the crime scene—including smoking, eating, drinking, and littering—that may alter the scene. No aspects of the scene, including a body at a death scene, should be moved or disturbed unless they pose a serious threat to investigating officers or bystanders. This means that no one should open or close faucets or flush toilets at the scene. Also, officers should avoid altering temperature conditions at the scene by adjusting windows, doors, or the heating or air conditioning.

Recording the Crime Scene Investigators have only a limited amount of time to work a crime site in its untouched state. The opportunity to permanently record the scene in its original state must not be lost. Such records not only will prove useful during the subsequent investigation but also are required for presentation at a trial in order to document the condition of the crime site and to delineate the location of phys- ical evidence. Notes, photography, and sketches are the three methods for crime-scene recording

FIGURE 2–1 The first investigators to arrive must secure the crime scene and establish the crime-scene perimeter.

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(see Figure 2–2). Ideally all three should be employed; how- ever, personnel and monetary limitations often prohibit the use of photography at every crime site. Under these circum- stances, departmental guidelines will establish priorities for deploying photographic resources. However, there is no rea- son not to make sketches and notes at the crime scene.

NOTES The note-taking process begins with the call to a crime-scene investigator to report to a scene. The notes should start by identifying the person who contacted the investigator, the time of the contact, and any preliminary information disclosed, including the case number. When the lead investigator arrives, the note taker should record the date and time of arrival, who is present, and the identities of any other personnel who are being contacted. If additional personnel are contacted, their names, titles, and time of arrival should be recorded. Investigators must keep a precise record of personnel movements in and out of the scene, beginning with an interview of the first responding officer

in order to record his or her movements. It is also important to record the tasks assigned to each member of a team, as well as

the beginning and ending times for the processing of the scene. Before the scene is sketched, photographed, or searched, the lead investigator carries out

the initial walk-through. During this walk-through, the investigator should take notes on many aspects of the crime scene in its original condition. These notes should be uniform in layout for all cases. The notes should be in ink (preferably black or blue) and written in a bound notebook. Most important, notes should be written at the time of the crime-scene investigation, not left to memory to record later.

Once a search for evidence has taken place, the team members mark the location of all evidence and fully describe each item in their notes. If a victim is present at a homicide scene, the investigator should observe and record the state of the body before the medical examiner or coroner moves it. Any preliminary identification of a victim or suspect should be recorded.

Audio-recording notes at a scene can be advantageous because detailed notes can be spoken much faster than they can be written. This may also leave hands free to carry out other tasks while recording the notes. Some investigators may use digital voice recorders to record their notes. These recordings are easily uploaded to a computer, but they must be copied to a disk to produce a hard copy. Another method of recording notes is by narrating a video of the crime scene. This has the advantage of combining note-taking with photography. However, at some point the video must be transcribed into a written document.

PHOTOGRAPHY The most important prerequisite for photographing a crime scene is for it to be unaltered. Unless injured people are involved, objects must not be moved until they have been photographed from all necessary angles. If objects are removed, positions changed, or items added, the photographs may not be admissible as evidence at a trial, and their intended value will be lost. If evidence has been moved or removed before photography, the fact should be noted in the report, but the evidence should not be reintroduced into the scene in order to take photographs.

Crime-scene photographs have great value in their ability to show the layout of the scene, the position of evidence to be collected, and the relation of objects at the scene to one another. Photographs taken from many angles can show possible lines of sight of victims, suspects, or wit- nesses. An accurate description of the scene must be available to investigators for future analysis. Photography is also important for documenting biological evidence in its original condition, as this kind of evidence is often altered during testing. Photographs cannot stand alone, however, and they are complementary to notes and sketches.

Crime-scene investigators use a digital camera, such as the digital single-lens reflex camera in Figure 2–3, to document crime scenes, and digital photography is rapidly becoming the method of choice in the field of forensic science. A digital photograph is made when a light-sensitive

FIGURE 2–2 Sketching a victim at the crime scene to show the victim’s relation to the crime scene.

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microchip inside a digital camera is exposed to light coming from an object or scene. A digital camera captures light on each of millions of tiny picture elements called pixels. The light is recorded on each pixel as a specific electric charge using a charged coupled device (CCD) or complementary metal oxide semiconductor (CMOS). The camera reads this charge number as image information, then stores the image as a file on a memory card.

The number of pixels used to capture light is directly related to the resolution of the picture. Resolution is defined as the mini- mum distance that must separate two objects in order for them to be viewed as distinct objects. The lower the distance needed, the greater the resolution of the photograph. Photographs of increas- ingly higher resolution show more and more detail and sharpness. The greater the number of pixels featured on the digital camera, the better the resolution will be.

Because the number of pixels on a digital camera is in the mil- lions, it is usually referred to in terms of megapixels. A camera that has four million pixels is a four-megapixel camera. A standard four- megapixel camera can create a clear image on a photographic print of up to 8 by 10 inches. As the number of megapixels increases, the clarity increases, allowing photographers to create bigger prints. Crime-scene photographers usually use cameras that feature as many as twelve megapixels or more.

The nature of digital images, however, opens digital photog- raphy to important criticisms within forensic science casework. Because the photographs are digital, they can be easily manipu- lated by using computer software. This manipulation goes beyond traditional photograph enhancement such as adjusting bright- ness and contrast or color balancing. Because the main function of crime-scene photography is to provide an accurate depiction, this is a major concern. To ensure that their digital im- ages are admissible, many jurisdictions set guidelines for determining the circumstances under which digital photography may be used and establish and enforce strict protocols for image security and chain of custody.

Photographic Procedures Each crime scene should be photographed as completely as possible. This means that the crime scene should include the area in which the crime took place and all adjacent areas where important acts occurred immediately before or after the commission of the crime. Overview photographs of the entire scene and surrounding area, including points of exit and entry, must be taken from various angles. If the crime took place indoors, the entire room should be photographed to show each wall area. Rooms adjacent to the actual crime site must be similarly photographed. If the crime scene includes a body, photographs must be taken to show the body’s position and location relative to the entire scene. Close-up photos depicting injuries and weapons lying near the body are also necessary (see Figure 2–4). After the body is removed from the scene, the surface beneath the body should be photographed.

As items of physical evidence are discovered, they are photographed to show their position and location relative to the entire scene. After these overviews are taken, close-ups should be taken to record the details of the object itself. When the size of an item is significant, a ruler or other measuring scale may be inserted near the object and included in the photograph as a point of reference. At a minimum, four photographs are required at a crime scene: an overview pho- tograph, a medium-range photograph, a close-up photograph, and a close-up photograph with a scale. These photographs create an adequate visual record of the position and appearance of an item of evidence at a crime scene.

The digital revolution promises to bring enhanced photographic capabilities to the crime scene. For example, individual images of the crime scene captured with a digital camera can be stitched together electronically to reveal a nearly 3-D panoramic view of the crime scene (see Figure 2–5).

FIGURE 2–3 An example of a digital single lens reflex (DSLR) camera.

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FIGURE 2–5 Individual images (top) are shown before being electronically stitched together into a single panoramic image (bottom). Individual photographs should be taken with about a 30 percent overlap.

(a) (b)

FIGURE 2–4 This sequence of crime-scene photographs shows the proper progression of photographing the scene. (a) The sequence begins with an overview photograph of the entry to the victim’s bedroom showing evidence markers in place. (b) The medium-range photograph shows the evidence marker next to the door denoting a cartridge case. (c) The close-up photograph shows the cartridge in detail with a scale in the photograph.

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The digital era promises new and elegant approaches to document the crime scene. Cameras such as that shown in Figure 2–6 are capable of taking dozens of digital images while scanning the crime scene. Photographic and laser data from multiple scan locations are combined to pro- duce 3-D models of the scene in full color that can be viewed from any vantage point, measured, and used for analysis and courtroom presentations.

Video Recording The use of digital video at crime scenes is becoming increasingly popular because the cost of this equipment is decreasing. The same principles used in crime-scene photographs apply to digital video. As with conventional photography, digital video should include the entire scene and the immediate surrounding area. Long shots as well as close-ups should be taken in a slow and systematic manner. Furthermore, it is desirable to have one crime- scene investigator narrate the events and scenes being recorded while another does the shooting.

However, there are some disadvantages to videos of crime scenes. First, although some cam- eras have a stabilization feature, most cameras will inevitably shake during filming. Also, zoom- ing and panning can be sloppy; these techniques should be used only occasionally and should be done very slowly. Extra noise due to wind or other investigators talking can obscure narration or may be inappropriate and damaging. Because of the “on the spot” nature of the narration, inves- tigators may stumble over words, which can be confusing when a video is used in court. To avoid this, some investigators record the video with the sound off and dub notes over it later.

Still images taken from videotape are usually of much poorer quality than those taken by a digital camera. Although video can capture the sounds and scenes of the crime site with relative ease, the technique cannot be used in place of still photography at this time. The still photograph remains unsurpassed in defining details for the human eye. Digital video can have advantages over still photography in certain situations. For example, modern video cameras allow the user to play back recordings of a scene and check it for completeness. In addition, many video cameras can also take still photographs, or stills can be created from the disc on a computer. Video es- sentially combines notes and photography.

SKETCHES Once photographs have been taken, the crime-scene investigator sketches the scene. The sketch serves many important functions in the legal investigation of a crime. If done correctly, a sketch can clearly show the layout of an indoor or outdoor crime scene and the relationship in space of all the items and features significant to the investigation. Sketches are especially important to illustrate the location of collected evidence. Possible paths of entry, exit, and movement through the scene may be speculated from a good sketch.

The investigator may have neither the skill nor the time to make a polished sketch of the scene. However, this is not required during the early phase of the investigation. What is neces- sary is a rough sketch containing an accurate depiction of the dimensions of the scene and

WEBEXTRA 2.1 Three-Dimensional Crime-Scene Imaging

rough sketch A draft representation of all essential information and measurements at a crime scene. This sketch is drawn at the crime scene.

FIGURE 2–6 A computer-controlled scanner has both a high-resolution, professional digital camera and a long-range laser rangefinder. The tripod- mounted device rotates a full 360 degrees, taking dozens of photographs and measuring millions of individual points. Photographic and laser data from multiple scan locations are combined to produce 3D models of the scene.

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showing the location of all objects having a bearing on the case. This may be achieved through the use of a sketching kit like the one shown in Figure 2–7.

A rough sketch is illustrated in Figure 2–8. It shows all recovered items of physical evidence as well as other important features of the crime scene. Objects are located in the sketch by distance measurements from two fixed points, such as the walls of a room. Distances shown on the sketch must be accurate and not the result of a guess or estimate. For this reason, all mea- surements are made with a tape measure. The simplest way to designate an item in a sketch is to assign it a number or letter. A legend or list placed below the sketch then correlates the letter to the item’s description. The sketch should also show a compass heading designating north as well as a title block designating the location of the crime scene and any case information.

Unlike the rough sketch, the finished sketch in Figure 2–9 is constructed with care and con- cern for aesthetic appearance. When the finished sketch is completed, it must reflect information contained within the rough sketch in order to be admissible evidence in a courtroom. Computer- aided drafting (CAD) has become the norm to reconstruct crime scenes from rough sketches. The software, ranging from simple, low-cost programs to complex, expensive programs, contains predrawn intersections and roadways or buildings and rooms onto which information can be entered (see Figure 2–10). A generous symbol library provides the operator with a variety of images that can be used to add intricate details such as blood spatters to a crime-scene sketch. Equipped with a zoom function, computerized sketching can focus on a specific area for a more detailed picture. CAD programs allow the operator to select scale size so that the ultimate prod- uct can be produced in a size suitable for courtroom presentation.

Conducting a Systematic Search for Evidence The search for physical evidence at a crime scene must be thorough and systematic. For a factual, unbiased reconstruction of the crime, the investigator, relying on his or her training and experi- ence, must not overlook any pertinent evidence. Even when suspects are immediately seized and the motives and circumstances of the crime are readily apparent, a thorough search for physical evidence must be conducted at once. Failure in this, even though it may seem unnecessary, can lead to accusations of negligence or charges that the investigative agency knowingly “covered up” evidence that would be detrimental to its case.

FIGURE 2–7 A basic kit for sketching the crime scene.

finished sketch A precise rendering of the crime scene, usually drawn to scale.

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FIGURE 2–8 Rough-sketch diagram of a crime scene.

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Assigning those responsible for searching a crime scene is a function of the investigator in charge. Except in major crimes, or when the evidence is complex, the assistance of a forensic scientist at the crime scene is usually not necessary; his or her role appropriately begins when evidence is submitted to the crime laboratory. As has already been observed, some police agen- cies have trained field evidence technicians to search for physical evidence at the crime scene. They have the equipment and skill to photograph the scene and examine it for the presence of fin- gerprints, footprints, tool marks, or any other type of evidence that may be relevant to the crime.

SEARCH PATTERNS How one conducts a crime-scene search will depend on the locale and size of the area, as well as on the actions of the suspect(s) and victim(s) at the scene. When possible, one person should supervise and coordinate the collection of evidence. Without proper control, the search may be conducted in an atmosphere of confusion with needless duplication of effort. The various search patterns that may be used can be observed in Figure 2–11.

FIGURE 2–9 Finished-sketch diagram of a crime scene.

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FIGURE 2–10 Construction of a crime-scene diagram with the aid of a computer-aided drafting program.

Grid search

Quadrant or zone search

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start

Spiral search method(c)(b)

(e)Wheel/Ray search(d)

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FIGURE 2–11 (a) Strip or line search pattern. (b) Grid search pattern. (c) Spiral search pattern. (d) Wheel or ray search pattern. (e) Quadrant or zone search pattern.

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Strip or Line Search Pattern In the line or strip method, one or two investigators start at the boundary at one end of the scene and walk straight across to the other side. They then move a little farther along the border and walk straight back to the other side. This method is best used in scenes where the boundaries are well established, because the boundaries dictate the beginning and end of the search lines. If the boundary is incorrectly chosen, important evidence may remain undiscovered outside the search area.

Grid Search Pattern The grid method employs two people performing line searches that originate from adjacent corners and form perpendicular lines. This method is very thorough, but the boundaries must be well established in order to use this method as well.

Spiral Search Pattern The spiral search pattern usually employs one person. The investigator moves either in an inward spiral from the boundary to the center of the scene or in an outward spiral from the center to the boundary. The inward spiral method is helpful because the searcher is moving from an area light with evidence to an area where more evidence will most likely be found. With either spiral approach the searcher can easily locate footprints leading away from the scene in any direction. However, completing a perfect spiral is often difficult, and evidence could be missed.

Wheel or Ray Search Pattern The wheel or ray method employs several people moving from the boundary straight toward the center of the scene (inward) or from the center straight to the boundary (outward). This method is not preferred because the areas between the “rays” are not searched.

Quadrant or Zone Search Pattern The quadrant or zone method divides the scene into zones or quadrants, and team members are assigned to search each section. Each of these sections can be subdivided into smaller sections for smaller teams to search thoroughly. This method is best suited for scenes that cover a large area. The areas searched must include all probable points of entry and exit used by the criminals.

LOCATING PHYSICAL EVIDENCE What to search for will be determined by the particular circumstances of the crime. Obviously, the skill of crime-scene investigators at recognizing evidence and searching relevant locations is paramount to successful processing of the crime scene. Although training will impart general knowledge for conducting a proper crime-scene investigation, ultimately the investigator must rely on experience gained from numerous investigations to form a successful strategy for recovering relevant physical evidence.

For example, in a homicide case, the search will center on the weapon and any evidence left as a result of contact between the victim and the assailant. The cross-transfer of evidence, such as hairs, fibers, and blood, between individuals involved in the crime is particularly useful for linking suspects to the crime scene and for corroborating events that transpired during the commission of the crime. During the investigation of a burglary, efforts will be made to locate tool marks at the point of entry. In most crimes, a thorough and systematic search for latent fin- gerprints is required.

Vehicle searches must be carefully planned and systematically carried out. The nature of the case determines how detailed the search must be. In hit-and-run cases, the outside and undercar- riage of the car must be examined with care. Particular attention is paid to looking for any evi- dence resulting from a cross-transfer of evidence between the car and the victim—this includes blood, tissue, hair, fibers, and fabric impressions. Traces of paint or broken glass may be located on the victim. In cases of homicide, burglary, kidnapping, and so on, all areas of the vehicle, inside and outside, are searched with equal care for physical evidence.

Collecting and Packaging Physical Evidence Physical evidence can be anything from massive objects to microscopic traces. Often, many items of evidence are obvious in their presence, but others may be detected only through examination in the crime laboratory. For example, minute traces of blood may be discovered on garments only after a thorough search in the laboratory, or the presence of hairs and fibers may be revealed in vacuum sweepings or on garments only after close laboratory scrutiny. For this reason, it is im- portant to collect possible carriers of trace evidence in addition to more discernible items. Hence, it may be necessary to take custody of all clothing worn by the participants in a crime.

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COLLECTING PHYSICAL EVIDENCE Each clothing item should be handled carefully and wrapped separately to avoid loss of trace materials. Critical areas of the crime scene should be vacuumed and the sweepings submitted to the laboratory for analysis. The sweepings from different areas must be collected and packaged separately. A portable vacuum cleaner equipped with a special filter attachment is suitable for this purpose (see Figure 2–12). Additionally, fingernail scrapings from individuals who were in contact with other individuals may contain minute fragments of evidence capable of linking the assailant and victim. The undersurface of each nail is best scraped with a dull object such as a toothpick to avoid cutting the skin. These scrapings will be subjected to microscopic examination in the laboratory.

The search for physical evidence must extend beyond the crime scene to the autopsy room of a deceased victim. Here, the medical examiner or coroner carefully examines the victim to establish a cause and manner of death. Tissues and organs are routinely retained for pathologi- cal and toxicological examination. At the same time, arrangements must be made between the examiner and investigator to secure a variety of items that may be obtainable from the body for laboratory examination (see page 102).

In recent years, many police departments have gone to the expense of purchasing and equip- ping “mobile crime laboratories” (see Figure 2–13) for their evidence technicians. However, the term mobile crime laboratory is a misnomer. These vehicles carry the necessary supplies to protect the crime scene; photograph, collect, and package physical evidence; and perform latent print development. They are not designed to carry out the functions of a chemical laboratory. Crime-scene search vehicle would be a more appropriate but perhaps less dramatic name for such a vehicle.

HANDLING EVIDENCE Investigators must handle and process physical evidence in a way that prevents any change from taking place between the time the evidence is removed from the crime scene and the time it is received by the crime laboratory. Changes can arise through contamination, breakage, evaporation, accidental scratching or bending, or improper or careless packaging. The use of latex gloves or disposable forceps when touching evidence often can prevent such problems. Any equipment that is not disposable should be cleaned and/or sanitized between collecting each piece of evidence. Evidence should remain unmoved until investigators have documented its location and appearance in notes, sketches, and photographs.

Evidence best maintains its integrity when kept in its original condition as found at the crime site. Whenever possible, one should submit evidence to the laboratory intact. The investigator normally should not remove blood, hairs, fibers, soil particles, and other types of trace evidence from garments, weapons, or other articles that bear them. Instead, he or she should send the entire object to the laboratory for processing.

FIGURE 2–12 Vacuum sweeper attachment, constructed of clear plastic in two pieces that are joined by a threaded joint. A metal screen is mounted in one half to support a filter paper to collect debris. The unit attaches to the hose of the vacuum sweeper. After a designated area of the crime scene is vacuumed, the filter paper is removed and retained for laboratory examination.

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Of course, if evidence is adhering to an object in a precarious manner, good judgment dic- tates removing and packaging the item. Use common sense when handling evidence adhering to a large structure, such as a door, wall, or floor; remove the specimen with a forceps or other ap- propriate tool. In the case of a bloodstain, one may either scrape the stain off the surface, transfer the stain to a moistened swab, or cut out the area of the object bearing the stain.

PACKAGING EVIDENCE The well-prepared evidence collector arrives at a crime scene with a large assortment of packaging materials and tools, ready to encounter any type of situation. Forceps and similar tools may be used to pick up small items. Unbreakable plastic pill bottles with pressure lids are excellent containers for hairs, glass, fibers, and various other kinds of small or trace evidence. Alternatively, manila envelopes, screw-cap glass vials, sealable plastic bags, or metal pillboxes are adequate containers for most trace evidence encountered at crime sites (see Figure 2–14). Charred debris recovered from the scene of a suspicious fire must be sealed in an airtight container to prevent the evaporation of volatile petroleum residues. New paint cans or tightly sealed jars are recommended in such situations (see Figure 2–15).

One should not use ordinary mailing envelopes as evidence containers because powders and fine particles will leak out of their corners. Instead, small amounts of trace evidence can be conveniently packaged in a carefully folded paper, using what is known as a “druggist fold” (see Figure 2–16). This consists of folding one end of the paper over by one-third, then folding the other end (one-third) over that, and repeating the process from the other two sides. After folding the paper in this manner, tuck the outside two edges into each other to produce a closed container that keeps the specimen from falling out.

P O L I C E

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FIGURE 2–13 Inside view of a mobile crime-scene van: (a) driver’s side and (b) passenger’s side.

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Place each different item or similar items collected at different locations in separate containers. Packaging evidence separately prevents damage through contact and prevents cross-contamination.

BIOLOGICAL MATERIALS Use only disposable tools to collect biological materials for packaging. If biological materials such as blood are stored in airtight containers, the accumulation of moisture may encourage the growth of mold, which can destroy their evidential value. In these instances, wrapping paper, manila envelopes, or paper bags are the recommended packaging materials (see Figure 2–17). As a matter of routine, all items possibly containing biological fluid evidence should be air-dried and placed individually in separate paper bags to ensure constant circulation of air around them. This will prevent the formation of mold and mildew. Paper packaging is easily written on, but seals may not be sturdy. Finally, place a red biohazard

(a)

(b) (c)

FIGURE 2–14 (a) Manila evidence envelope. (b) Metal pillboxes. (c) Sealable plastic evidence bag.

FIGURE 2–15 Airtight metal cans used to package arson evidence.

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sticker on both the secured evidence bag and the property receipt to ensure that all handlers will be aware the item is contaminated with biological fluids, such as blood, saliva, or semen (see Table 2–1).

DNA EVIDENCE The advent of DNA analysis brought one of the most significant recent advances in crime-scene investigation. This technique is valuable for making it possible to identify suspects through detecting and analyzing minute quantities of DNA deposited on evidence as a result of contact with saliva, sweat, or skin cells. The search for DNA evidence should include any and all objects with which the suspect or victim may have come into bodily contact. Likely sources of DNA evidence include stamps and envelopes that have been licked, a cup or can that has touched a person’s lips, chewing gum, the sweatband of a hat, and a bed sheet containing dead skin cells.

One key concern during the collection of a DNA-containing specimen is contamination. Contamination—in this case, introducing foreign DNA—can occur from coughing or sneezing onto evidence during the collection process. Transfer of DNA can also occur when items of evidence are incorrectly placed in contact with each other during packaging. To prevent contami- nation, the evidence collector must wear a face mask and lab coat, use disposable latex gloves, and work with disposable forceps. The evidence collector must also take into consideration that biological materials, such as dried blood, should be considered potentially infectious. It’s recom- mended practice that the biological evidence collector wear disposable coveralls, shoe covers, and eye protection as an extra precaution to avoid contaminating DNA evidence and being ex- posed to infectious diseases.

FIGURE 2–16 A druggist fold is used to package paint transfer evidence.

FIGURE 2–17 Paper bags are recommended evidence containers for objects suspected of containing blood and semen stains. Each object should be packaged in a separate bag.

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Blood analysis has great evidential value when it allows the investigator to demonstrate a transfer between a victim and a suspect. For this reason, all clothing from both the victim and suspect should be collected and sent to the laboratory for examination, even when the presence of blood on a garment does not appear obvious to the investigator. Laboratory search procedures are far more revealing and sensitive than any that can be conducted at the crime scene.

A detailed description of the proper collection and packaging of various types of physical evidence will be discussed in forthcoming chapters.

Maintaining the Chain of Custody Continuity of possession, or the chain of custody, must be established whenever evidence is presented in court as an exhibit. Adherence to standard procedures in recording the location of evidence, marking it for identification, and properly completing evidence submission forms for laboratory analysis is the best guarantee that the evidence will withstand inquiries of what hap- pened to it from the time of its finding to its presentation in court. This means that every person who handled or examined the evidence must be accounted for. Failure to substantiate the evi- dence’s chain of custody may lead to serious questions regarding the authenticity and integrity of the evidence and examinations of it.

All items of physical evidence should be carefully packaged and marked upon their retrieval at crime sites. This should be done with the utmost care to avoid destroying their evidential value or restricting the number and kind of examinations to which the criminalist may subject them. If possible, the evidence itself should be marked for identification. Normally, the collector’s initials and the date of collection are inscribed directly on the article. However, if the evidence collector is unsure of the necessity of marking the item itself or of where to mark it, it is best to omit this step. Once an evidence container is selected for the evidence, whether a box, bag, vial, or can, it also must be marked for identification. Evidence containers often have a preprinted identification form that the evidence collector fills out. Otherwise, the collector must attach an evidence tag to the container. The investigator who packaged the evidence must write his or her initials and the date on the evidence tape seal. Anyone who removes the evidence for further testing or observation at a later time should try to avoid breaking the original seal if possible so that the information on the seal will not be lost. The person who reseals the packaging should record his or her initials and the date on the new seal.

TABLE 2–1 Best Practices in Biological Evidence Packaging Containers

Use paper bags, manila envelopes, cardboard boxes, and similar porous materials for all biological evidence. Use butcher paper or art paper for wrapping evidence, for padding in the evidence container, and/or as a general drop cloth to collect trace evidence. Package evidence and seal the container to protect it from loss, cross-transfer, contamination, and/or deleterious change. For security purposes, seal the package in such a manner that opening it causes obvious damage or alteration to the container or its seal.

Item Packaging Package each item separately; avoid commingling items to prevent cross-contamination. Use a biohazard label to indicate that a potential biohazard is present. Plastic bags are not preferred for storage because of the possibility of bacterial growth or mold. If drying wet evidence is not possible, place the evidence in an impermeable, nonporous container and place the container in a refrigerator that maintains a temperature of 2–8°C (approximately 35–46°F) and that is located away from direct sunlight until the evidence can be air-dried or submitted to the laboratory. Seal each package with evidence tape or other seals, such as heat seals and gum seals; if possible, do not use staples. Mark across the seal with the sealer’s identification or initials and the date.

Reprinted in part from The Biological Evidence Preservation Handbook: Best Practices for Evidence Han- dlers, http://nvlpubs.nist.gov/nistpubs/ir/2013/NIST.IR.7928.pdf.

chain of custody A list of all people who came into possession of an item of evidence.

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A minimum chain-of-custody record would show the collector’s initials, location of the evidence, and date of collection. If the evidence is turned over to another individual for care or delivery to the laboratory, this transfer must be recorded in notes and other appropriate forms. In fact, every individual who possesses the evidence must maintain a written record of its acquisi- tion and disposition. Frequently, all of the individuals involved in the collection and transporta- tion of the evidence may be requested to testify in court. Thus, to avoid confusion and to retain complete control of the evidence at all times, the chain of custody should be kept to a minimum.

Obtaining Standard/Reference Samples The examination of evidence, whether soil, blood, glass, hair, fibers, and so on, often requires comparison with a known standard/reference sample. Although most investigators have little difficulty recognizing and collecting relevant crime-scene evidence, few seem aware of the necessity and importance of providing the crime lab with a thorough sampling of standard/ reference materials. Such materials may be obtained from the victim, a suspect, or other known sources. For instance, investigation of a hit-and-run incident may require the removal of standard/ reference paint from a suspect vehicle. This will permit its comparison to paint recovered at the scene. Similarly, hair found at the crime scene will be of optimum value only when compared to standard/reference hairs removed from the suspect and victim. Likewise, bloodstained evidence must be accompanied by a buccal swab standard/reference sample obtained from all relevant crime-scene participants. The quality and quantity of standard/reference specimens often deter- mine the evidential value of crime-scene evidence, and these standard/reference specimens must be treated with equal care.

Some types of evidence must also be accompanied by the collection of substrate controls. These are materials adjacent or close to areas where physical evidence has been deposited. For example, substrate controls are normally collected at arson scenes. If an investigator suspects that a particular surface has been exposed to gasoline or some other accelerant, the investigator should also collect a piece of the same surface material that is believed not to have been exposed to the accelerant. At the laboratory, the substrate control is tested to ensure that the surface on which the accelerant was deposited does not interfere with testing procedures. Another common example of a substrate control is a material on which a bloodstain has been deposited. Unstained areas close to the stain may be sampled for the purpose of determining whether this material will have an impact on the interpretation of laboratory results.

Thorough collection and proper packaging of standard/reference specimens and substrate controls are the mark of a skilled investigator.

Submitting Evidence to the Laboratory Evidence is usually submitted to the laboratory either by personal delivery or by mail shipment. The method of transmittal is determined by the distance the submitting agency must travel to the laboratory and the urgency of the case. If the evidence is delivered personally, the deliverer should be familiar with the case, to facilitate any discussions between laboratory personnel and the deliverer concerning specific aspects of the case.

If desired, most evidence can be conveniently shipped by mail. However, postal regula- tions restrict the shipment of certain chemicals and live ammunition and prohibit the mailing of explosives. In such situations, the laboratory must be consulted to determine the disposition of these substances. Care must also be exercised in the packaging of evidence in order to prevent breakage or other accidental destruction while it is in transit to the laboratory.

Most laboratories require that an evidence submission form accompany all evidence submitted. One such form is shown in Figure 2–18. This form must be properly completed. Its information will enable the laboratory analyst to make an intelligent and complete examination of the evidence. Particular attention should be paid to providing the laboratory with a brief description of the case history. This information will allow the examiner to analyze the specimens in a logical sequence and make the proper comparisons, and it will also facilitate the search for trace quantities of evidence.

The particular kind of examination requested for each type of evidence is to be delineated. However, the analyst will not be bound to adhere strictly to the specific tests requested by the investigator. As the examination proceeds, new evidence may be uncovered, and as a result the complexity of the case may change. Furthermore, the analyst may find the initial requests incom- plete or not totally relevant to the case. Finally, a list of items submitted for examination must be

standard/reference sample Physical evidence whose origin is known, such as fibers or hair from a suspect, that can be compared to crime-scene evidence.

buccal swab A swab of the inner portion of the cheek; cheek cells are usually collected to determine the DNA profile of an individual.

substrate control Uncontaminated surface material close to an area where physical evidence has been deposited. This sample is to be used to ensure that the surface on which a sample has been deposited does not interfere with laboratory tests.

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included on the evidence submission form. Each item is to be packaged separately and assigned a number or letter, which should be listed in an orderly and logical sequence on the form.

Ensuring Crime-Scene Safety The increasing spread of AIDS and hepatitis B has sensitized the law enforcement community to the potential health hazards at crime scenes. Law enforcement officers have an extremely small chance of contracting AIDS or hepatitis at the crime scene. Both diseases are normally transmit- ted by the exchange of body fluids, such as blood, semen, and vaginal and cervical secretions; intravenous drug needles and syringes; and transfusion of infected blood products. However, the presence of blood and semen at crime scenes presents the investigator with biological specimens of unknown origin; the investigator has no way of gauging what health hazards they may contain. Therefore, caution and protection must be used at all times.

FIGURE 2–18 An example of a properly completed evidence submission form.

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Fortunately, inoculation can easily prevent hepatitis B infection in most people. Further- more, the federal Occupational Safety and Health Administration (OSHA) requires that law en- forcement agencies offer hepatitis B vaccinations to all officers who may have contact with body fluids while on the job, at no expense to the officer.

Each crime scene is unique and carries with it its own collection of hazards. Fortunately, a number of options are available to crime-scene investigators for dealing with the potential haz- ards that crime scenes present. More frequently than not, once the scene is secured and isolated, it should become apparent that the locale may not contain urgent safety concerns, as in burglaries and car thefts. Nevertheless, routine safety practices must be enforced. This includes donning la- tex or nitrite gloves. The latter provides better protection from chemicals. Gloves offer protection from inadvertent contact with blood or other biological materials. They also prevent accidental deposition of fingerprints on objects the scene investigators may touch. Gloves must be changed frequently; in fact, a new pair of gloves must be worn for each item of evidence handled by the investigator. When removed, the gloves must be disposed of in a biohazard bag.

Protective footwear is an important component of the crime-scene investigator’s garb. Shoes must be covered with rubber booties when moving about indoors. The investigator should rou- tinely wear shoes or boots that provide good traction and ample support. Inexpensive shoes are recommended, as the investigator must be prepared to dispose of them if they become contami- nated with unknown liquids or chemicals.

A basic concern of the crime scene is eye protection. It’s appropriate to wear eyeglasses or goggles at crime scenes. However, if concerns exist about encountering splashing liquids, a face shield should be donned to maximize eye and face protection.

Crime scenes that contain the greatest risks to health and safety typically entail exposure to potentially life-threatening biological hazards. These scenes call for maximum respiratory, eye, and skin protection. A wide variety of respiratory masks are available. They include single and double filter masks. Tyvek protective suits are a good option for keeping biohazards off the skin. These suits allow the wearer to move about with ease and flexibility.

When processing and collecting evidence at a crime scene, personnel should be alert to sharp objects, knives, hypodermic syringes, razor blades, and similar items. If such sharp objects are encountered and must be recovered as evidence, the items should be placed in a puncture- resistant container and properly labeled.

When potentially infectious materials are present at a crime scene, personnel should main- tain a red biohazard plastic bag for the disposal of contaminated gloves, clothing, masks, pencils, wrapping paper, and so on. On departure from the scene, the biohazard bag must be taped shut and transported to an approved biohazardous waste pickup site.

Legal Considerations at the Crime Scene In police work, perhaps no experience is more exasperating or demoralizing than to see valuable evidence excluded from use against the accused because of legal considerations. This situation most often arises from what is deemed an “unreasonable” search and seizure of evidence. There- fore, removal of any evidence from a person or from the scene of a crime must be done in confor- mity with Fourth Amendment privileges: “The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizure, shall not be violated, and no warrants shall issue, but upon probable cause, supported by oath or affirmation, and particu- larly describing the place to be searched, and the persons or things to be seized.”

Since the 1960s, the Supreme Court has been particularly concerned with defining the cir- cumstances under which the police can search for evidence in the absence of a court-approved search warrant. A number of allowances have been made to justify a warrantless search: (1) the existence of emergency circumstances, (2) the need to prevent the immediate loss or destruction of evidence, (3) a search of a person and property within the immediate control of the person, provided it is made incident to a lawful arrest, and (4) a search made by consent of the parties involved. In cases other than these, police must be particularly cautious about processing a crime scene without a search warrant. In 1978, the Supreme Court addressed this very issue and in so doing set forth guidelines for investigators to follow in determining the propriety of conducting a warrantless search at a crime scene. Significantly, the two cases decided on this issue related

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to homicide and arson crime scenes, both of which are normally subjected to the most intensive forms of physical evidence searches by police.

In the case of Mincey v. Arizona,1 the Court dealt with the legality of a four-day search at a homicide scene. The case involved a police raid on the home of Rufus Mincey, who had been suspected of dealing drugs. Under the pretext of buying drugs, an undercover police officer forced entry into Mincey’s apartment and was killed in a scuffle that ensued. Without a search warrant, the police spent four days searching the apartment, recovering, among other things, bul- lets, drugs, and drug paraphernalia. These items were subsequently introduced as evidence at the trial. Mincey was convicted and on appeal contended that the evidence gathered from his apart- ment, without a warrant and without his consent, was illegally seized. The Court unanimously upheld Mincey’s position, stating:

We do not question the right of the police to respond to emergency situations. Numerous state and federal cases have recognized that the Fourth Amendment does not bar police officers from making warrantless entries and searches when they reasonably believe that a person within is in need of immediate aid. Similarly, when the police come upon the scene of a homicide they may make a prompt warrantless search of the area to see if there are other victims or if a killer is still on the premises. . . . Except for the fact that the offense under investigation was a homicide, there were no exigent circumstances in this case. . . . There was no indication that evidence would be lost, destroyed or removed during the time required to obtain a search warrant. Indeed, the police guard at the apartment minimized that possibility. And there is no suggestion that a search warrant could not easily and con- veniently have been obtained. We decline to hold that the seriousness of the offense under investigation itself creates exigent circumstances of the kind that under the Fourth Amend- ment justify a warrantless search.

In Michigan v. Tyler,2 a business establishment leased by Loren Tyler and a business part- ner was destroyed by fire. The fire was finally extinguished in the early hours of the morning; however, hampered by smoke, steam, and darkness, fire officials and police were prevented from thoroughly examining the scene for evidence of arson. The building was then left unat- tended until eight a.m. that day, when officials returned and began an inspection of the burned premises. During the morning search, assorted items of evidence were recovered and removed from the building. On three other occasions—four days, seven days, and twenty-five days after the fire—investigators reentered the premises and removed additional items of evidence. Each of these searches was made without a warrant or without consent, and the evidence seized was used to convict Tyler and his partner of conspiracy to burn real property and related offenses. The Su- preme Court upheld the reversal of the conviction, holding the initial morning search to be proper but contending that evidence obtained from subsequent reentries to the scene was inadmissible: “We hold that an entry to fight a fire requires no warrant, and that once in the building, officials may remain there for a reasonable time to investigate the cause of a blaze. Thereafter, additional entries to investigate the cause of the fire must be made pursuant to the warrant procedures.”

The message from the Supreme Court is clear: when time and circumstances permit, obtain a search warrant before investigating and retrieving physical evidence at the crime scene.

1 437 U.S. 385 (1978). 2 436 U.S. 499 (1978).

chapter summary Physical evidence includes all objects that can establish or disprove that a crime has been committed or can link a crime and its victim or its perpetrator. Forensic science begins at the crime scene. Here, investigators must recognize and properly preserve evidence for laboratory examination. The first officer to arrive is responsible for securing the crime scene. Once the

scene is secured, relevant investigators record the crime scene by using photographs, sketches, and notes. Before processing the crime scene for physical evidence, the investigator should make a preliminary examination of the scene as it was left by the perpetrator. The search for physical evidence at a crime scene must be thorough and systematic. The search pattern

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review questions

selected normally depends on the size and locale of the scene and the number of collectors participating in the search.

Physical evidence can be anything from massive objects to microscopic traces. Often, many items of evidence are clearly visible, but others may be detected only through exam- ination at the crime laboratory. For this reason, it is important to collect possible carriers of trace evidence, such as cloth- ing, vacuum sweepings, and fingernail scrapings, in addition to more discernible items. Each different item or similar items collected at different locations must be placed in a separate

container. Packaging evidence separately prevents damage through contact and prevents cross-contamination.

During the collection of evidence, the chain of custody, a record for denoting the location of the evidence, must be maintained. In addition, proper standard/reference samples, such as hairs, a buccal swab, and fibers, must be collected at the crime scene and from appropriate subjects for comparison in the laboratory. The removal of any evidence from a person or from the scene of a crime must be done in accordance with appropriate search and seizure protocols.

1. The term ___________ encompasses all objects that can establish or disprove whether a crime has been commit- ted or can link a crime and its victim or its perpetrator.

2. True or False: Scientific evaluation of crime-scene evi- dence can usually overcome the results of a poorly con- ducted criminal investigation. ___________

3. True or False: The techniques of physical evidence col- lection require a highly skilled individual who must spe- cialize in this area of investigation. ___________

4. All unauthorized personnel must be ___________ from crime scenes.

5. True or False: Failure to protect a crime scene properly may result in the destruction or altering of evidence. ___________

6. The ___________ arriving on the scene of a crime is responsible for taking steps to preserve and protect the area to the greatest extent possible, and this person must rely on his or her training to deal with any violent or hazardous circumstances.

7. At a crime scene, first priority should be given to ob- taining ___________ for individuals in need of it and attempting to minimize disturbance of evidence.

8. True or False: The boundaries of the crime scene, de- noted by crime-scene tape, rope, or traffic cones, should encompass only the center of the scene where the crime occurred. ___________

9. Even though no unauthorized personnel are admitted to the scene, an accurate ___________ must be kept of those who do enter and exit the scene and the time they do so.

10. True or False: The lead investigator will immediately proceed to gain an overview of the situation and develop a strategy for the systematic examination of the crime scene during the final survey. ___________

11. Three methods for recording the crime scene are ___________, ___________, and ___________.

12. True or False: The note-taking process begins with the call to a crime-scene investigator to report to a scene. ___________

13. The crime-scene notes should include a precise record of personnel movements in and out of the scene starting with the ___________.

14. True or False: Crime-scene notes should be written from memory back at the laboratory. ___________

15. Before located evidence is collected, it must be fully de- scribed in the investigator’s ___________.

16. True or False: When an injured or deceased victim is pres- ent at the scene, the state of the body before being moved should be observed but not recorded. ___________

17. The most important prerequisite for photographing a crime scene is to have it in a(n) ___________ condition.

18. Photographs of physical evidence must include overviews as well as ___________ to record the details of objects.

19. True or False: The value of crime-scene photographs lies in their ability to show the layout of the scene, posi- tion of witnesses, and relation of people to one another in the scene. ___________

20. The most commonly used camera for crime-scene pho- tography is the ___________ camera, which can be film or digital.

21. A digital camera captures light on a light-sensitive ___________.

22. True or False: Each crime scene should be photographed as completely as possible in a logical succession, and the photographs should include the area in which the crime actually took place and all adjacent areas where impor- tant acts occurred. ___________

23. The succession of photographs taken at a crime scene is ___________ photographs first and ___________ pho- tographs last.

24. True or False: Overview photographs should include only points of entry and points of exit. ___________

25. To ensure that their digital images will be admissible, many jurisdictions have developed or are developing ___________ for the use of digital photography to avoid the possibility of enhancement or doctoring of crime- scene photographs.

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26. The process of ___________ the crime scene essentially combines notes and photography.

27. Unlike the rough sketch, the ___________ is constructed with care and concern for aesthetic appearance and must be drawn to scale.

28. ___________ programs provide an extensive symbol li- brary and may create a three-dimensional sketch.

29. An investigator need only draw a(n) ___________ sketch at the crime scene to show its dimensions and pertinent objects.

30. A detailed search of the crime scene for physical evi- dence must be conducted in a(n) ___________ manner.

31. The crime-scene search is undertaken to locate ___________.

32. True or False: The search patterns that may be used to search a crime scene for evidence include the line pat- tern, grid pattern, polar coordinate pattern, and spiral pattern. ___________

33. True or False: If the investigator does not recognize physical evidence or does not properly preserve it for laboratory examination, sophisticated laboratory instru- mentation or technical expertise can salvage the situa- tion and attain the desired results. ___________

34. Besides the more obvious items of physical evidence, possible ___________ of trace evidence must be col- lected for detailed examination in the laboratory.

35. Whenever possible, trace evidence (is, is not) to be re- moved from the object that bears it.

36. Each item collected at the crime scene must be placed in a(n) ___________ container.

37. True or False: An ordinary mailing envelope is con- sidered a good general-purpose evidence container. ___________

38. An airtight container (is, is not) recommended packag- ing material for bloodstained garments.

39. As a matter of routine, all items of clothing are to be ___________ before packaging.

40. True or False: Charred debris recovered from the scene of an arson is best placed in a porous container. ___________

41. The possibility of future legal proceedings requires that a(n) ___________ be established with respect to the possession and location of physical evidence.

42. Most physical evidence collected at the crime scene will require the accompanying submission of ___________ material for comparison purposes.

43. In the case of Mincey v. Arizona, the Supreme Court restricted the practice of conducting a(n) ___________ search at a homicide scene.

44. In the case of Michigan v. Tyler, the Supreme Court dealt with search-and-seizure procedures at a(n) ___________ scene.

application and critical thinking

1. You are the first officer at the scene of an outdoor assault. You find the victim bleeding but conscious, with two of the victim’s friends and several onlookers standing nearby. You call for backup and quickly glance around but see no one fleeing the scene. Describe the steps you would take while you wait for backup to arrive.

2. What kind of search pattern(s) would investigators be most likely to employ in each of the following situations?

a. Two people searching a small area with well-defined boundaries

b. Several people searching a large area

c. A single person searching a large area

3. Officer Bill Walter arrives at the scene of an apparent murder: a body bearing several gunshot wounds lies on the floor of a small, un-air-conditioned house in late July. A pungent odor almost overwhelms him when he enters the house, so he opens a window to allow him to breathe so he can investigate the scene. While airing out the house, he secures the scene and interviews bystanders. When he inspects the scene, he discovers very little blood in the room and little evidence of a struggle. What mistake did Officer Walter make in his investigation? What conclu- sion did he draw about the scene from his observations?

4. Officer Martin Guajardo is the first responder at an ap- parent homicide scene. After securing the area, inter- viewing the sole witness, and calling for backup, he begins to search for evidence. He makes note of a bloody knife lying next to the body, with a small scrap of bloody cloth clinging precariously to the knife. Because it is a very windy day, Officer Guajardo removes the scrap of fabric and seals it in a plastic bag. A few moments later, a crime-scene team, including a photographer, arrives to take over the investigation. What mistakes, if any, did Officer Guajardo make before the crime-scene team arrived?

5. During his search of a homicide scene, investigator David Gurney collects evidence that includes a bloody shirt. After the crime-scene team has completely pro- cessed the scene, Investigator Gurney packages the shirt in a paper bag, seals the bag, and labels it to indicate the contents. He then delivers the shirt to the laboratory with an evidence submission form. There, a forensic scientist breaks the seal, removes the shirt, and performs a se- ries of tests on it. He replaces the shirt, discards the old seal, and places a new seal on the package containing his initials and the date on which it was resealed. What mistakes, if any, were made in handling the shirt?

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52 CHAPTER 2

6. What important elements are missing from the following crime-scene sketch?

G A

DOOR

W IN

D O

A—Dining room table B—Chair C—Overturned chair D—0.38 Revolver E—Male body F—Table G—Chair

DINING ROOM

Sketch by Officer John Smith

2741 Aragon St. 9/6/06

B B C

B BB W IN

D O

W further references

The Biological Evidence Preservation Handbook: Best Prac- tices for Evidence Handlers http://nvlpubs.nist.gov/ nistpubs/ir/2013/NIST.IR.7928.pdf

Crime Scene Investigation: A Guide for Law Enforce- ment, 2013, http://www.nfstc.org/bja-programs/ crime-scene-investigation-guide/

Geberth, Vernon J., Practical Homicide Investigation: Tac- tics, Procedures, and Forensic Techniques, 4th ed. Boca Raton, Fla.: CRC Press, 2006.

Ogle, R. R., Jr., Crime Scene Investigation and Reconstruction, 3rd ed. Upper Saddle River, N.J.: Prentice Hall, 2011.

Osterburg, James W., and Richard H. Ward, Criminal Investigation—A Method for Reconstructing the Past, 6th ed. Cincinnati, Ohio: Anderson, 2011.

Shaler, R. C., Crime Scene Forensics: A Scientific Method Approach, Boca Raton, Fla.: CRC Press, 2012.

case analysis

1. What were the main challenges facing investigators who were collecting evidence in the case? Give specific examples.

2. Explain how investigators used reference samples to de- termine that the victims had been held at the residence located at 881 Lope De Vega.

3. Explain how investigators used soil evidence to deter- mine that the victims’ bodies had been buried and later moved to the site where they were discovered.

Investigators looking into the kidnapping and murder of DEA special agent Enrique Camarena and DEA source Al- fredo Zavala faced several hurdles that threatened to derail their efforts to collect evidence in the case. These hurdles almost prevented forensics experts from determining the facts of the case and threatened to undermine the investiga- tion of the crime. However, despite these obstacles, use of standard forensic techniques eventually enabled investiga- tors to solve the case. Read about the Camarena case in the following Case Files, then answer the following questions:

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Michael P. Malone Special Agent, Laboratory Division Federal Bureau of Investigation, Washington, D.C.

Case Study

The Enrique Camarena Case: A Forensic Nightmare On February 7, 1985, US Drug Enforcement Agency (DEA) Special Agent (SA) Enrique Camarena was abducted near the US Consulate in Guadalajara, Mexico. A short time later, Capt. Alfredo Zavala, a DEA source, was also abducted from a car near the Guadalajara Airport. These two abductions would trigger a series of events leading to one of the largest investigations ever conducted by the DEA and would result in one of the most extensive cases ever received by the FBI Laboratory . . .

The Abduction On February 7, 1985, SA Camarena left the DEA resident office to meet his wife for lunch. On this day, a witness observed a man being forced into the rear seat of a light-colored compact car in front of the Camelot Restaurant and provided descriptions of several of the assailants. After some initial reluctance, Primer Comandante Pavon-Reyes of the Mexican Federal Judicial Police (MFJP) was put in charge of the investigation, and Mexican inves- tigators were assigned to the case. Two known drug traffickers, Rafael Caro-Quintero and Ernesto Fonseca, were quickly developed as suspects . . .

The Investigation During February 1985, searches of several residences and ranches throughout Mexico proved fruitless, despite the efforts of the DEA task force assigned to investigate this mat- ter and the tremendous pressure being applied by the US government to accelerate the investigation. High-level US government officials, as well as their Mexican counterparts, were becoming directly involved in the case. It is believed that, because of this “heat,” the Mexican drug traffickers and certain Mexican law enforcement officials fabricated a plan. According to the plan, the MFJP would receive an anonymous letter indicating that SA Camarena and Captain Zavala were being held at the Bravo drug gang’s ranch in La Angostura, Michoacan, approximately 60 miles southeast of Guadalajara. The MFJP was supposed to raid the ranch, eliminate the drug gang, and eventually discover the bodies of SA Camarena and Captain Zavala buried on the ranch. The DEA would then be notified and the case would be closed. Thus, the Bravo gang would make an easy scapegoat.

During early March, MFJP officers raided the Bravo ranch before the DEA agents ar- rived. In the resulting shootout, all of the gang members, as well as one MFJP officer, were killed. However, due to a mix-up, the bodies of SA Camarena and Captain Zavala were not buried on the Bravo ranch in time to be discovered as planned. Shortly after this shootout, a passerby on a road near the Bravo ranch found two partially decomposed bodies wrapped in plastic bags. The bodies were removed and transported to a local morgue, where they were autopsied. The DEA was then advised of the discovery of the bodies and their subsequent removal to another morgue in Guada- lajara, where a second autopsy was performed.

Cadaver number 1 was quickly identified by the fingerprint expert as SA Camarena. Although Mexican officials would not allow the second body to be identified at this time, it was later identified through dental records as Captain Zavala.

The FBI forensic team requested permission to process the clothing, cordage, and burial sheet found with the bodies, but the request was denied. However, they were allowed to cut small, “known” samples from these items and obtain hair samples from both bodies. Soil samples were also removed from the bodies and the clothing items.

In late March 1985, DEA agents located a black Mercury Grand Marquis that they believed was used in the kidnapping or transportation of SA Camarena. The vehicle had been stored in a garage in Guadalajara, and a brick wall had been constructed at the entrance to conceal it. The vehicle was traced to a Ford dealership owned by Caro-Quintero. Under the watchful eye of the MFJP at the Guadalajara Airport, the FBI forensic team processed the vehicle for any hair, fiber, blood, and/or fingerprint evidence it might contain.

Undated photo of Enrique Camarena.

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During April 1985, the MFJP informed the DEA that they believed they had located the residence where SA Camarena and Captain Zavala had been held. The FBI forensic team was im- mediately dispatched to Guadalajara; however, they were not al- lowed to proceed to the residence, located at 881 Lope De Vega, until an MFJP forensic team had processed the residence and had removed all of the obvious evidence.

On the first day after their arrival, the FBI forensic team sur- veyed and began a crime-scene search of the residence and sur- rounding grounds (see Figure 1). The residence consisted of a large, two-story structure with a swimming pool, covered patio, aviary, and tennis court surrounded by a common wall. The most logical place to hold a prisoner at this location would be in the small outbuilding located to the rear of the main residence. This outbuilding, designated as the “guest house” by investigators, consisted of a small room with a beige rug and an adjoining bath- room. The entire room and bathroom were processed for hairs, fibers, and latent fingerprints. The single door into this room was made of steel and reinforced by iron bars. It was ultimately deter- mined by means of testimony and forensic evidence that several individuals interrogated and tortured SA Camarena in this room. In addition, a locked bedroom, located on the second floor of the main house, was also processed, and the bed linens were removed from a single bed. Known carpet samples were taken from every room in the residence.

A beige Volkswagen Atlantic parked under a carport at the rear of the residence fit the general description of the smaller ve- hicle noted by the witness to SA Camarena’s abduction. The VW Atlantic was also processed for hairs, fibers, and fingerprints.

On the second day, a thorough grounds search was conducted. As FBI forensic team members were walking around the tennis court, they caught a glimpse of something blue in one of the drains. On closer inspection, there appeared to be a folded license plate at the bottom of the drain. The license plate was retrieved, unfolded, and photographed. The MFJP officers, all of whom were now at the tennis court, became upset at this discovery, and one of them immediately contacted his superior at MFJP headquarters, who ordered them to secure the license plate until the assistant primer comandante arrived on the scene. Upon his arrival approximately 20 minutes later, he seized the license plate and would not allow the Americans to conduct any further searches.

In September 1985, DEA personnel went to La Primavera Park and recovered a soil sample. This sample matched the soil samples from SA Camarena and Captain Zavala’s cadavers almost grain for grain, which indicated that this site was almost certainly their burial site before they were relocated to the Bravo ranch.

Later that fall, after further negotiations between the US and the Mexican governments, permission was finally granted for an FBI forensic team to process the evidence seized by the MFJP forensic team from 881 Lope De Vega the previous April. The evidence consisted of small samples the MFJP had taken

54 CHAPTER 2

of SA Camarena’s burial sheet, a piece of rope used to bind SA Camarena, a portion of a pillowcase removed from bedroom number 3, a piece of unsoiled rope removed from the covered patio, and a laboratory report prepared by the MFJP Crime Lab- oratory. The remainder of the evidence had been destroyed for “health reasons.”

In January 1986, a drug trafficker named Rene Verdugo, who was considered to be a high-ranking member of the Caro- Quintero gang, was apprehended and taken to San Diego, where he was arrested by the DEA. He was then transported to Washington, D.C., where samples of his hair were taken. He refused to testify before the federal grand jury investigating the Camarena case. Later that year, DEA personnel obtained hair samples in Mexico City from Sergio Espino-Verdin, a former federal comandante who is believed to have been SA Camarena’s primary interrogator during his ordeal at 881 Lope De Vega.

The Trial In July 1988, the main trial for the murder, interrogation, and abduction of SA Camarena began in US District Court in Los Angeles, California. The forensic evidence presented in this trial identified 881 Lope De Vega as the site where SA Camarena had been held. The evidence also strongly associated two Mexi- can citizens, Rene Verdugo and Sergio Espino-Verdin, with the “guest house” at 881 Lope De Vega. Several types of forensic evidence were used to associate SA Camarena with 881 Lope De Vega: forcibly removed head hairs found in the “guest house” and bedroom number 4, in the VW Atlantic, and in the Mercury Grand Marquis, and two types of polyester rug fibers: a dark, rose-colored fiber and a light-colored fiber (see Figures 2 and 3). Fabric evidence was also presented, which demonstrated the sim- ilarities of color, composition, construction, and design between SA Camarena’s burial sheet and the two pillowcases recovered from bedrooms number 3 and 5.

Based on this evidence associating SA Camarena and 881 Lope De Vega, the FBI Laboratory examiner was able to testify that SA Camarena was at this residence, as well as in the VW Atlantic and the Mercury Grand Marquis, and that he had been in a position such that his head hairs were forcibly removed. Captain Alfredo Zavala was also found to be associated with the “guest house” at 881 Lope De Vega. Light-colored nylon rug fi- bers found on samples of his clothing taken at the second autopsy matched the fibers from the “guest house” carpet.

A detailed model of the residence at 881 Lope De Vega was prepared by the Special Projects Section of the FBI Laboratory for the trial (see Figure 4). Over twenty trial charts were also prepared to explain the various types of forensic evidence. These charts proved invaluable in clarifying the complicated techniques and characteristics used in the examination of the hair, fiber, fab- ric, and cordage evidence (see Figure 5).

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Sliding Gate

Tennis Court

License Plates Found

BATHHOUSE & SPA

AVIARY

PRIVATE BUSINESS

WALL

Covered Porch

SIDE ENTRANCE

VW ATLANTICGROUNDS

WALL AND ARCHWAYS

SIDE ENTRANCEC

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Swimming Pool

Storage

GUEST ROOM

MAID’S ROOM

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KITCHEN MAIN HOUSE

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GARAGE Area

FIGURE 1 A diagram of the 881 Lope De Vega grounds. Camarena was held prisoner in the guest house. Source: FBI Law Enforcement Bulletin, September, 1989.

THE CRIME SCENE 55

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FIGURE 3 A trial chart showing hair comparisons between known Camarena hairs and hairs recovered from the Mercury Gran Marquis.

FIGURE 2 A trial chart showing hair comparisons between known Camarena hairs and hairs recovered from 881 Lope De Vega.

FIGURE 4 A model of 881 Lope De Vega prepared as a trial exhibit.

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Mercury CamarenaHead Hair Blood on Floor Mat

VW Atlantic

Camarena Head Hair

Blood on Tissue

Guest House

Camarena Head Hair

Zavala Clothes

Nylon

Bedroom #3

Camarena Blindfold Polyester

Pillow Case Camarena

Burial Sheet

Bedroom #4

Camarena Head Hair

Camarena Blindfold & Burial Sheet

Polyester

Bedroom #5

Pillow Case Camarena

Burial Sheet

Tennis Court

License Plate

VW/Merc.

Camarena Burial Sheet

Camarena Head Hair

Bedroom #4 Polyester

Pillow Case Bedrooms #3 and #5

Soil La

Primavera

Source — Blindfold/

Rope

Camarena Head Hair

Bedrooms #3 and #4 Polyester

Camarena Blindfold

Tape

Camarena Burial

Cordage

Burial Rope from Covered

Patio

Zavala Clothing

Zavala Head Hair

Guest House Nylon

Soil La

Primavera

CATEGORIES OF FORENSIC EVIDENCE IN CAMARENA CASE

TYPE OF EVIDENCE

Carpet Fibers

Fabric Match

Cordage Match

Tape MatchLOCATION Hair Misc.

FIGURE 5 A trial chart used to show the association of Camarena and Zavala with various locations. Source: Federal Bureau of Investigation.

THE CRIME SCENE 57

Conclusion After an eight-week trial, conducted under tight security and involving hundreds of witnesses, all of the defendants were found

guilty and convicted on all counts, and are currently serving lengthy sentences.

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Amanda Knox: A Flawed Case of Murder

In September 2007, Amanda Knox moved to Perugia, Italy, as a foreign exchange student attending language classes at the University for Foreigners. Knox shared an upstairs flat in a cottage with Meredith Kercher and two other women. Within weeks of her arrival, Knox became romantically linked to an Italian student, Raffaele Sollecito, and began spending nights at his home.

On November 1, Kercher was brutally murdered. Early that afternoon, Kercher’s naked body was found inside her bedroom covered by a bedspread soaked in blood and with stab wounds to her throat. As the investigation proceeded, police matched fingerprints found in Kercher’s bedroom to Rudy Guede, whom Knox and Kercher had met weeks earlier when he was playing guitar on the downstair floor of their cottage flat. Guede was subsequently arrested and charged with the Kercher murder. His DNA was later found at the crime scene, on and inside Kercher’s body. The prosecution also charged Knox and Sollecito with murder and sexual assault.

According to the prosecution’s theory, Knox was part of a satanic ritual sex game that went out of control. The Knox case

became the subject of intense media scrutiny, focusing in part on Knox’s alleged romantic escapades. The prosecution alleged that the murder weapon was a kitchen knife

found in Sollecito’s kitchen that had Kercher’s DNA on the blade and Knox’s DNA on the handle. The DNA on the handle could have arisen from Knox’s handling of the knife while cooking for Sollecito. Experts questioned the veracity of the DNA protocols conducted on the knife blade. Expert analysis concluded that the knife wounds were inconsistent with the knife recovered from Sollecito’s residence. Guede was convicted of Kercher’s murder. Knox was convicted of slander, sexual violence, and murder and sentenced to 26 years in prison. Four years later her conviction was set aside by the Italian supreme court and a new trial was ordered.

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After studying this chapter you should be able to: Review the common types of physical evidence encountered at crime scenes

Explain the difference between the identification and comparison of physical evidence

Define and contrast individual and class characteristics of physical evidence

Appreciate the value of class evidence as it relates to a criminal investigation

List and explain the function of national databases available to forensic scientists

physical evidence

class characteristics comparison identification individual

characteristics product rule Rapid DNA

KEY TERMS

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It would be impossible to list all the objects that could conceivably be of importance to a crime; every crime scene obviously has to be treated on an individual basis, having its own peculiar his- tory, circumstances, and problems. It is practical, however, to list items whose scientific exami- nation is likely to yield significant results in ascertaining the nature and circumstances of a crime. The investigator who is thoroughly familiar with the recognition, collection, and analysis of these items, as well as with laboratory procedures and capabilities, can make logical decisions when the uncommon and unexpected are encountered at the crime scene. Just as important, a qualified evidence collector cannot rely on collection procedures memorized from a pamphlet but must be able to make innovative, on-the-spot decisions at the crime scene.

Common Types of Physical Evidence 1. Blood, semen, and saliva. All suspected blood, semen, or saliva—liquid or dried, animal

or human—present in a form to suggest a relation to the offense or the people involved in a crime. This category includes blood or semen dried onto fabrics or other objects, as well as cigarette butts that may contain saliva residues. These substances are subjected to serologi- cal and biochemical analysis to determine their identity and possible origin.

2. Documents. Any handwriting and typewriting submitted so that authenticity or source can be determined. Related items include paper, ink, indented writings, obliterations, and burned or charred documents.

3. Drugs. Any substance seized in violation of laws regulating the sale, manufacture, distribu- tion, and use of drugs.

4. Explosives. Any device containing an explosive charge, as well as all objects removed from the scene of an explosion that are suspected to contain the residues of an explosive.

5. Fibers. Any natural or synthetic fiber whose transfer may be useful in establishing a relation- ship between objects and/or people.

6. Fingerprints. All prints of this nature, latent and visible. 7. Firearms and ammunition. Any firearm, as well as discharged or intact ammunition, sus-

pected of being involved in a criminal offense. 8. Glass. Any glass particle or fragment that may have been transferred to a person or object

involved in a crime. Windowpanes containing holes made by a bullet or other projectile are included in this category.

9. Hair. Any animal or human hair present that could link a person with a crime. 10. Impressions. Tire markings, shoe prints, depressions in soft soils, and all other forms of tracks.

Glove and other fabric impressions, as well as bite marks in skin or foodstuffs, are also included. 11. Organs and physiological fluids. Body organs and fluids are submitted for toxicology to

detect possible existence of drugs and poisons. This category includes blood to be analyzed for the presence of alcohol and other drugs.

12. Paint. Any paint, liquid or dried, that may have been transferred from the surface of one object to another during the commission of a crime. A common example is the transfer of paint from one vehicle to another during an automobile collision.

13. Petroleum products. Any petroleum product removed from a suspect or recovered from a crime scene. The most common examples are gasoline residues removed from the scene of an arson, or grease and oil stains whose presence may suggest involvement in a crime.

14. Plastic bags. A disposable polyethylene bag such as a garbage bag may be evidential in a homicide or drug case. Examinations are conducted to associate a bag with a similar bag in the possession of a suspect.

15. Plastic, rubber, and other polymers. Remnants of these manufactured materials recovered at crime scenes may be linked to objects recovered in the possession of a suspect perpetrator.

16. Powder residues. Any item suspected of containing firearm discharge residues (see Figure 3–1). 17. Serial numbers. This category includes all stolen property submitted to the laboratory for

the restoration of erased identification numbers. 18. Soil and minerals. All items containing soil or minerals that could link a person or object

to a particular location. Common examples are soil embedded in shoes and safe insulation found on garments.

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19. Tool marks. This category includes any object suspected of containing the im- pression of another object that served as a tool in a crime. For example, a screw- driver or crowbar could produce tool marks by being impressed into or scraped along a surface of a wall.

20. Vehicle lights. Examination of vehicle headlights and taillights is normally con- ducted to determine whether a light was on or off at the time of impact.

21. Wood and other vegetative matter. Any fragments of wood, sawdust, shavings, or vegetative matter discovered on clothing, shoes, or tools that could link a person or object to a crime location.

The Significance of Physical Evidence The examination of physical evidence by a forensic scientist is usually undertaken for identification or comparison.

Identification Identification has as its purpose the determination of the physical or chemical iden- tity of a substance with as near absolute certainty as existing analytical techniques will permit. For example, the crime laboratory is frequently asked to identify the chemical composition of an illicit-drug preparation that may contain heroin, cocaine, barbiturates, and so on. It may be asked to identify gasoline in residues recovered from the debris of a fire, or it may have to identify the nature of explosive residues— for example, dynamite or TNT. Also, the identification of blood, semen, hair, or wood would, as a matter of routine, include a determination of species origin. For example, did an evidential bloodstain originate from a human as opposed to a dog or cat? Each of these requests requires the analysis and ultimate identification of a spe- cific physical or chemical substance to the exclusion of all other possible substances.

The process of identification first requires the adoption of testing procedures that give characteristic results for specific standard materials. Once these test results have been established, they may be permanently recorded and used repeatedly to prove the identity of suspect materials. For example, to ascertain that a particular suspect powder is heroin, the test results on the powder must be identical to those that have been previously ob- tained from a known heroin sample. Second, identification requires that the number and type of tests needed to identify a substance be sufficient to exclude all other substances. This means that the examiner must devise a specific analytical scheme that will eliminate all but one substance from consideration. Hence, if the examiner concludes that a white powder contains heroin, the test results must have been comprehensive enough to have excluded all other drugs—or, for that matter, all other substances—from consideration.

Simple rules cannot be devised for defining what constitutes a thorough and foolproof ana- lytical scheme. Each type of evidence obviously requires different tests, and each test has a different degree of specificity. Thus, one substance could conceivably be identified by one test, whereas another may require a combination of five or six different tests to arrive at an identifica- tion. In a science in which the practitioner has little or no control over the quality and quantity of the specimens received, a standard series of tests cannot encompass all possible problems and pitfalls. So the forensic scientist must determine at what point the analysis can be concluded and the criteria for positive identification satisfied; for this, he or she must rely on knowledge gained through education and experience. Ultimately, the conclusion will have to be substantiated be- yond any reasonable doubt in a court of law.

Comparison A comparison analysis subjects a suspect specimen and a standard/reference specimen to the same tests and examinations for the ultimate purpose of determining whether they have a common origin. For example, the forensic scientist may place a suspect at a particular location by noting the simi- larities of a hair found at the crime scene to hairs removed from a suspect’s head (see Figure 3–2). Or a paint chip found on a hit-and-run victim’s garment may be compared with paint removed from a vehicle suspected of being involved in the incident. The forensic comparison is actually a two-step

identification The process of determining a substance’s physical or chemical identity. Drug analysis, species de- termination, and explosive residue analysis are typical examples of this undertaking in a forensic setting.

comparison The process of ascertaining whether two or more objects have a common origin.

FIGURE 3–1 The gun is fired at a set distance from the target and the gunpowder left on the target is compared to powder stains found on a victim’s clothing. The density and shape of the powder stains vary with the distance the gun was fired.

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procedure. First, combinations of select properties are chosen from the suspect and the standard/ reference specimen for comparison. The question of which and how many properties are selected obviously depends on the type of materials being examined. (This subject will receive a good deal of discussion in forthcoming chapters.) The overriding consideration must be the ultimate eviden- tial value of the conclusion. This brings us to the second objective. Once the examination has been completed, the forensic scientist must draw a conclusion about the origins of the specimens. Do they or do they not come from the same source? Certainly if one or more of the properties selected for comparison do not agree, the analyst will conclude that the specimens are not the same and hence could not have originated from the same source. Suppose, on the other hand, that all the prop- erties do compare and the specimens, as far as the examiner can determine, are indistinguishable. Does it logically follow that they come from the same source? Not necessarily so.

To comprehend the evidential value of a comparison, one must appreciate the role that prob- ability has in ascertaining the origins of two or more specimens. Simply defined, probability is the frequency of occurrence of an event. If a coin is flipped one hundred times, in theory we can expect heads to come up 50 times. Hence, the probability of the event (heads) occurring is 50 in 100. In other words, probability defines the odds at which a certain event will occur.

INDIVIDUAL CHARACTERISTICS Evidence that can be associated with a common source with an extremely high degree of probability is said to possess individual characteristics. Examples of this are the ridge characteristics of fingerprints, random striation markings on bullets or tool marks, irregular and random wear patterns in tire or footwear impressions, handwriting characteristics, irregular edges of broken objects that can be fitted together like a jigsaw puzzle (see Figure 3–3), or sequentially made plastic bags that can be matched by striation marks running across the bags (see Figure 3–4). In all of these cases, it is not possible to state with mathematical exactness the probability that the specimens are of common origin; it can only be concluded that this probability is so high as to defy mathematical calculations or human comprehension. Furthermore, the conclusion of common origin must be substantiated by the practical experience of the examiner. For example, the French scientist Victor Balthazard has mathematically determined that the probability of two individuals having the same fingerprints

FIGURE 3–2 Side-by-side comparison of hairs.

individual characteristics Properties of evidence that can be attributed to a common source with an extremely high degree of certainty.

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is one out of 1 � 1060, or 1 followed by 60 zeros. This probability is so small as to exclude the possibility of any two individuals having the same fingerprints. This contention is also supported by the experience of fingerprint examiners who, after classifying millions of prints over the past hundred years, have never found any two to be exactly alike.

CLASS CHARACTERISTICS One disappointment awaiting the investigator unfamiliar with the limitations of forensic science is the frequent inability of the laboratory to relate physical

FIGURE 3–4 The bound body of a young woman was recovered from a river. Her head was covered with a black polyethylene trash bag (shown on the right). Among the items recovered from one of several suspects was a black polyethylene trash bag (shown on the left). A side-by-side comparison of the two bags’ extrusion marks and pigment bands showed them to be consecutively manufactured. This information allowed investigators to focus their attention on one suspect, who ultimately was convicted of the homicide.

FIGURE 3–3 The body of a woman was found with evidence of a stablike wound in the neck. A pathologist found a knife blade tip in the wound in the neck. The knife blade tip was compared with the broken blade of a knife found in the trousers pocket of the accused. A close examination reveals the fit of the indentations on the edges and individual characteristics of stria from the sharpening procedure.

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evidence to a common origin with a high degree of certainty. Evidence is said to possess class characteristics when it can be associated only with a group and never with a single source. Here again, probability is a determining factor. For example, if we compare two one-layer automobile paint chips of a similar color, their chance of originating from the same car is not nearly as great as when we compare two paint chips having seven similar layers of paint, not all of which were part of the car’s original color. The former will have class characteristics and could only be associated at best with one car model (which may number in the thousands), whereas the latter may be judged to have individual characteristics and to have a high probability of originating from one specific car.

Blood offers another good example of evidence that can have class characteristics. For ex- ample, suppose that two blood specimens are compared and both are found to be of human origin, type A. The frequency of occurrence in the population of type A blood is 26 percent— hardly offering a basis for establishing the common origin of the stains. However, if other blood factors are also determined and are found to compare, the probability that the two blood samples originated from a common source increases. Thus, if one uses a series of blood factors that occur independently of each other, one can apply the product rule to calculate the overall frequency of occurrence of the blood in a population.

For example, in the O. J. Simpson case, a bloodstain located at the crime scene was found to contain a number of factors that compared to O. J.’s blood:

class characteristics Properties of evidence that can be associated only with a group and never with a single source.

product rule Multiplying together the frequen- cies of independently occurring genetic markers to obtain an over- all frequency of occurrence for a genetic profile.

The product of all the frequencies shown in the table determines the probability that any one individual possesses such a combination of blood factors. In this instance, applying the product rule, 0.25 × 0.85 × 0.02 equals 0.0044, or 0.44 percent, or about 1 in 200 people who would be expected to have this particular combination of blood factors. These bloodstain factors did not match either of the two victims, Nicole Brown Simpson or Ronald Goldman, thus eliminating them as possible sources of the blood. Although the forensic scientist has still not individualized the bloodstains to one person—in this case, O. J. Simpson—data have been provided that will permit investigators and the courts to better assess the evidential value of the crime-scene stain. As we will learn in Chapter 11, the product rule is used to determine the frequency of occurrence of DNA profiles typically determined from blood and other biological materials. Importantly, modern DNA technology provides enough factors to allow an analyst to individualize blood, semen, and other biological materials to a single person or an identical twin.

Assessing the Significance of Physical Evidence One of the current weaknesses of forensic science is the inability of the examiner to assign exact or even approximate probability values to the comparison of most class physical evidence. For example, what is the probability that a nylon fiber originated from a particular sweater, or that a hair came from a particular person’s head, or that a paint chip came from a car suspected to have been involved in a hit-and-run accident? Few statistical data are available from which to derive this information, and in a society that is increasingly dependent on mass-produced products, the gathering of such data is becoming an increasingly elusive goal.

One of the primary endeavors of forensic scientists must be to create and update statistical databases for evaluating the significance of class physical evidence. Of course, when such information—for example, the population frequency of blood factors—is available, it is used; but for the most part, the forensic scientist must rely on personal experience when called on to interpret the significance of class physical evidence.

People who are unfamiliar with the realities of modern criminalistics are often disappointed to learn that most items of physical evidence retrieved at crime scenes cannot be linked defini- tively to a single person or object. Although investigators always try to uncover physical evi- dence with individual characteristics—such as fingerprints, tool marks, and bullets—the chances of finding class physical evidence are far greater. To deny or belittle the value of such evidence

Blood Factors Frequency

A 26% EsD 85% PGM 2+ 2– 2%

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is to reject the potential role that criminalistics can play in a criminal investigation. In practice, criminal cases are fashioned for the courtroom around a collection of diverse elements, each pointing to the guilt or involvement of a party in a criminal act. Often, most of the evidence gathered is subjective in nature, prone to human error and bias. The believability of eyewitness accounts, confessions, and informant testimony can all be disputed, maligned, and subjected to severe attack and skepticism in the courtroom. Under these circumstances, errors in human judg- ment are often magnified to detract from the credibility of the witness.

Assessing the Value of Physical Evidence The value of class physical evidence lies in its ability to corroborate events with data in a manner that is, as nearly as possible, free of human error and bias. It is the thread that binds together other investigative findings that are more dependent on human judgments and, therefore, more prone to human failings. The fact that scientists have not yet learned to individualize many kinds of physical evidence means that criminal investigators should not abdicate or falter in their pursuit of all investigative leads. However, the ability of scientists to achieve a high degree of success in evaluating class physical evidence means that criminal investigators can pursue their work with a much greater chance of success.

Admittedly, in most situations, trying to define the significance of an item of class evidence in exact mathematical terms is a difficult if not impossible goal. Although class evidence is by its nature not unique, our common experience tells us that meaningful items of physical evidence, such as those listed on pages 60–61, are extremely diverse in our environment. Select, for exam- ple, a colored fiber from an article of clothing and try to locate the exact same color on the clothing of random individuals you meet, or select a car color and try to match it to other automobiles you see on local streets. Furthermore, keep in mind that a forensic comparison actually goes beyond a mere color comparison and involves examining and comparing a variety of chemical and/or physical properties (see Figure 3–5). The point is that the chances are low of encountering two indistinguishable items of physical evidence at a crime scene that actually originated from differ- ent sources. Obviously, given these circumstances, only objects that exhibit a significant amount of diversity in our environment are deemed appropriate for classification as physical evidence.

FIGURE 3–5 Side-by-side comparison of fibers.

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In the same way, when one is dealing with more than one type of class evidence, their collective presence may lead to an extremely high certainty that they originated from the same source. As the number of different objects linking an individual to a crime increases, the probability of involvement increases dramatically. A classic example of this situation can be found in the evidence presented at the trial of Wayne Williams. Wayne Williams was charged with the murders of two individuals in the Atlanta, Georgia, metropolitan area; he was also linked to the murders of ten other boys or young men. An essential element of the state’s case involved the association of Williams with the victims through a variety of fiber evidence. Twenty-eight different types of fibers linked Williams to the murder victims, evidence that the forensic examiner characterized as “overwhelming.”

Cautions and Limitations in Dealing with Physical Evidence In further evaluating the contribution of physical evidence, one cannot overlook one important reality in the courtroom: the weight or significance accorded physical evidence is a determination left entirely to the trier of fact, usually a jury of laypeople. Given the high esteem in which scien- tists are generally held by society and the infallible image created for forensic science by books and television, it is not hard to understand why scientifically evaluated evidence often takes on an aura of special reliability and trustworthiness in the courtroom. Often physical evidence, whether individual or class, is accorded great weight during jury deliberations and becomes a primary factor in reinforcing or overcoming lingering doubts about guilt or innocence. In fact, a number of jurists have already cautioned against giving carte blanche approval to admitting scientific testimony without first considering its relevance in a case. Given the potential weight of scientific evidence, failure to take proper safeguards may unfairly prejudice a case against the accused.

Physical evidence may also exclude or exonerate a person from suspicion. For instance, if type A blood is linked to the suspect, all individuals who have type B, AB, or O blood can be eliminated from consideration. Because it is not possible to assess at the crime scene what value, if any, the scientist will find in the evidence collected, or what significance such findings will ultimately have to a jury, a thorough collection and scientific evaluation of physical evidence must become a routine part of all criminal investigations.

Just when an item of physical evidence crosses the line that distinguishes class from individual is a difficult question to answer and is often the source of heated debate and honest disagreement among forensic scientists. How many striations are necessary to individualize a mark to a single tool and no other? How many color layers individualize a paint chip to a single car? How many ridge characteristics individualize a fingerprint, and how many handwriting characteristics tie a person to a signature? These questions defy simple answers. The task of the forensic scientist is to find as many characteristics as possible to compare one substance with another. The significance attached to the findings is decided by the quality and composition of the evidence, the case history, and the ex- aminer’s experience. Ultimately, the conclusion can range from mere speculation to near certainty.

There are practical limits to the properties and characteristics the forensic scientist can select for comparison. Carried to the extreme, no two things in this world are alike in every detail. Mod- ern analytical techniques have become so sophisticated and sensitive that the criminalist must be careful to define the limits of natural variation among materials when interpreting the data gathered from a comparative analysis. For example, we will learn in the next chapter that two properties, density and refractive index, are best suited for comparing two pieces of glass. But the latest tech- niques that have been developed to measure these properties are so sensitive that they can even distinguish glass originating from a single pane of glass. Certainly this goes beyond the desires of a criminalist trying to determine only whether two glass particles originated from the same window. Similarly, if the surface of a paint chip is magnified 1,600 times with a powerful scanning electron microscope, it is apparent that the fine details that are revealed could not be duplicated in any other paint chip. Under these circumstances, no two paint chips, even those coming from the same sur- face, could ever compare in the true sense of the word. Therefore, practicality dictates that such ex- aminations be conducted at a less revealing, but more meaningful, magnification (see Figure 3–6).

Distinguishing evidential variations from natural variations is not always an easy task. Learning how to use the microscope and all the other modern instruments in a crime laboratory properly is one thing; gaining the proficiency needed to interpret the observations and data is another. As new crime laboratories are created and others expand to meet the requirements of the law enforcement community, many individuals are starting new careers in forensic science. They must be cautioned that merely reading relevant textbooks and journals is no substitute for experience in this most practical of sciences.

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Forensic Databases In a criminal investigation, the ultimate contribution a criminalist can make is to link a suspect to a crime through comparative analyses. This comparison defines the unique role of the criminal- ist in a criminal investigation. Of course, a one-on-one comparison requires a suspect. Little or nothing of evidential value can be accomplished if crime-scene investigators acquire fingerprints, hairs, fibers, paint, blood, and semen without the ability to link these items to a suspect. In this re- spect, computer technology has dramatically altered the role of the crime laboratory in the inves- tigative process. No longer is the crime laboratory a passive bystander waiting for investigators to uncover clues about who may have committed a crime. Today, the crime laboratory is on the forefront of the investigation seeking to identify perpetrators. This dramatic reversal of the role of

FIGURE 3–6 (a) Two-layer paint chip magnified 244× with a scanning electron microscope. (b) The same paint chip viewed at a magnification of 1,600×.

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forensic science in criminal investigation has come about through the creation of computerized databases that not only link all 50 states, but tie together police agencies throughout the world.

Fingerprint Databases The premier model of all forensic database systems is the Integrated Automated Fingerprint Identi- fication System (IAFIS), a national fingerprint and criminal history system maintained by the FBI. IAFIS, which first became operational in 1999, contains fingerprints and access to corresponding criminal history information for nearly 75 million subjects (or 750 million fingerprint images), which are submitted voluntarily to the FBI by state, local, and federal law enforcement agencies. In the United States each state has its own Automated Fingerprint Identification System (AFIS), which is linked to the FBI’s IAFIS. A crime-scene fingerprint or latent fingerprint is a dramatic find for the criminal investigator. Once the quality of the print has been deemed suitable for the IAFIS search, the latent-print examiner creates a digital image of the print with either a digital camera or a scanner. Next, the examiner, with the aid of a coder, marks points on the print to guide the com- puterized search. The print is then electronically submitted to IAFIS, and within minutes the search is completed against all fingerprint images in IAFIS; the examiner may receive a list of potential candidates and their corresponding fingerprints for comparison and verification (see Figure 3–7).

Many countries throughout the world have created national automated fingerprint identifica- tion systems that are comparable to the FBI’s model. For example, a computerized fingerprint database containing nearly nine million ten-print records connects the Home Office and 43 police forces throughout England and Wales.

DNA Databases In 1998, the FBI’s Combined DNA Index System (CODIS) became fully operational. CODIS enables federal, state, and local crime laboratories to electronically exchange and compare DNA profiles, thereby linking crimes to each other and to convicted offenders. All 50 states have en- acted legislation to establish a data bank containing DNA profiles of individuals convicted of felony sexual offenses (and other crimes, depending on each state’s statute). CODIS creates in- vestigative leads from three indexes: the forensic, offender, and arrestee indices. The forensic in- dex currently contains about 470,000 DNA profiles from unsolved crime-scene evidence. Based on a match, police in multiple jurisdictions can identify serial crimes, allowing coordination of

Latent Print File Print

FIGURE 3–7 The computerized search of a fingerprint database first requires that selected ridge characteristics be designated by a coder. The positions of these ridge characteris- tics serve as a basis for comparing the latent print against file fingerprints.

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investigations and sharing of leads developed independently. The offender index contains the profiles of more than ten million convicted individuals. The FBI has joined numerous states that collect DNA samples from those awaiting trial and will collect DNA from detained immigrants. This information will be entered into the arrestee index database, presently at 1.5 million.1

Constitutional issues regarding the appropriateness of collecting DNA from arrestees not convicted of any crime, but who nevertheless were the subject of a CODIS search against DNA collected from unsolved crimes, was decided in the case of Maryland v. King.2

When officers make an arrest supported by probable cause to hold for a serious offense and bring the suspect to a station to be detained in custody, taking and analyzing a cheek swab of the arrestee’s DNA is, like fingerprinting and photographing, a legitimate police booking procedure that is reasonable under the Fourth Amendment.

With the Supreme Court sanctioning the collection of cheek or buccal swabs from arrestees, the necessity for the analysis of a swab as close to the time of arrest as possible becomes apparent. The term Rapid DNA has become part of the lingo of forensic science and describes approaches for rapidly obtaining a DNA profile from a buccal swab. A number of compact instruments are already commercially available and others are being developed.3 These will allow for the determination of a DNA profile from a buccal swab in less than 90 minutes. Experts envision that Rapid DNA devices will take their place alongside fingerprinting units for the routine processing of arrestees.

Unfortunately, hundreds of thousands of samples are backlogged, still awaiting DNA analy- sis and entry into the offender index. Law enforcement agencies search this index against DNA profiles recovered from biological evidence found at unsolved crime scenes. This approach has proven to be tremendously successful in identifying perpetrators because most crimes involving biological evidence are committed by repeat offenders.

Several countries throughout the world have initiated national DNA data banks. The United Kingdom’s National DNA Database, established in 1995, was the world’s first national data- base. Currently it holds more than four million profiles, and DNA can be taken for entry into the database from anyone arrested for an offense likely to involve a prison term. In a typical month, matches are found linking suspects to 26 murders; 57 rapes and other sexual offenses; and 3,000 motor vehicle, property, and drug crimes. The National DNA Data Bank, housed in Ottawa, Canada, contains more than 250,000 DNA profiles from convicted individuals and has assisted in more than 24,000 cases including 1,740 murders and more than 3,000 sexual assaults.

Other Databases The National Integrated Ballistics Information Network (NIBIN), maintained by the Bureau of Alcohol, Tobacco, Firearms and Explosives, allows firearms analysts to acquire, digitize, and compare markings made by a firearm on bullets and cartridge casings recovered from crime scenes. The NIBIN program currently has 236 sites that are electronically joined to 16 multistate regions. The heart of NIBIN is the Integrated Ballistic Identification System (IBIS), comprising a microscope and a computer unit that can capture an image of a bullet or cartridge casing. The images are then forwarded to a regional server, where they are stored and correlated against other images in the regional database. IBIS does not positively match bullets or casings fired from the same weapon; this must be done by a firearms examiner. IBIS does, however, facilitate the work of the firearms examiner by producing a short list of candidates for the examiner to manually compare. More than 47,000 “hits” have been recorded by the NIBIN system, many of them yield- ing investigative information not obtainable by other means.

The International Forensic Automotive Paint Data Query (PDQ) database contains chemi- cal and color information pertaining to original automotive paints. This database, developed and maintained by the Forensic Laboratory Services of the Royal Canadian Mounted Police (RCMP), contains information about make, model, year, and assembly plant on more than 13,000 vehicles with a library of more than 50,000 layers of paint. Contributors to the PDQ include the RCMP and forensic laboratories in Ontario and Quebec, as well as 40 U.S. forensic laboratories and police agencies in 21 other countries. Accredited users of PDQ are required to submit 60 new

1 Collecting DNA at Arrest: Policies, Practices, and Implications, https://www.ncjrs.gov/pdffiles1/nij/grants/242812.pdf.

3 J.A. Lounsbury and J.P. Landers, “Ultrafast Amplification of DNA on Plastic Microdevices for Forensic Short Tan- dem Repeat Analysis,” Journal of Forensic Sciences, 58 (2013):866.

2 133 S.Ct. 1236 (2013).

Rapid DNA A process for developing DNA profiles from a buccal swab in 90 minutes or less that are compatible with a CODIS search.

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70 CHAPTER 3

Gerald Wallace In 1975, police found Gerald Wallace’s body on his living room couch. He had been savagely beaten, his hands bound with an electric cord. Detectives searched his ransacked house, cataloging every piece of evidence they could find. None of it led to the murderer. They had no witnesses. Six- teen years after the fact, a lone fingerprint, lifted from a

cigarette pack found in Wallace’s house and kept for 16 years in the police files, was entered into the Pennsylvania State Police AFIS database. Within minutes, it hit a match. That print, police say, gave investigators the identity of a man who had been at the house the night of the murder. Police talked to him. He led them to other witnesses, who led them to the man police ultimately charged with the murder of Gerald Wallace.

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The Center City Rapist Fort Collins, Colorado, and Philadelphia, Pennsylvania, are sep- arated by nearly 1,800 miles, but in 2001 they were tragically linked through DNA. Troy Graves left the Philadelphia area in 1999, joined the Air Force, and settled down with his wife in Colorado. A frenzied string of eight sexual assaults around the Colorado University campus set off a manhunt that ultimately

resulted in the arrest of Graves. However, his DNA profile inex- tricably identified him as Philadelphia’s notorious “Center City rapist.” This assailant attacked four women in 1997 and brutally murdered Shannon Schieber, a Wharton School graduate stu- dent, in 1998. His last known attack in Philadelphia was the rape of an 18-year-old student in August 1999, shortly before he left the city. In 2002 Graves was returned to Philadelphia, where he was sentenced to life in prison without parole.

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NIBIN Links Handgun to Suspects After a series of armed robberies in which suspects fired shots, the sheriff’s office of Broward County, Florida, entered the cartridge casings from the crime scenes into NIBIN. Through NIBIN, four of the armed robberies were linked to the same .40-caliber handgun. A short time later, sheriff’s deputies noticed suspicious activity around a local business. When they attempted

to interview the suspects, the suspects fled in a vehicle. During the chase, the suspects attempted to dispose of a handgun; depu- ties recovered the gun after making the arrests. The gun was test-fired and the resulting evidence entered into NIBIN, which indicated a possible link between this handgun and the four pre- vious armed robberies. Firearms examiners confirmed the link through examination of the original evidence. The suspects were arrested and charged with four prior armed robbery offenses.

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4 Foster & Freeman Limited, http://www.fosterfreeman.co.uk.

automotive paint samples per year for addition to the database. The PDQ database has found its greatest utility in the investigation of hit-and-runs by providing police with possible make, model, and year information to aid in the search for the unknown vehicle.

The previously described databases are maintained and controlled by government agencies. There is one exception: a commercially available computer retrieval system for comparing and iden- tifying crime-scene shoe prints known as SICAR (shoeprint image capture and retrieval).4 SICAR’s pattern-coding system enables an analyst to create a simple description of a shoe print by assigning codes to individual pattern features (see Figure 3–8). Shoe print images can be entered into SICAR by either a scanner or a digital camera. This product has a comprehensive shoe sole database (Sole- mate) that includes more than 22,000 footwear entries providing investigators with a means for linking a crime-scene footwear impression to a particular shoe manufacturer. A second database, TreadMate, has been created to house tire tread patterns. Currently, it contains 6,000 records.

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PHYSICAL EVIDENCE 71

Aztec Gold Metallic Hit and Run A 53-year-old man was walking his dog in the early morn- ing hours. He was struck and killed by an unknown vehicle and later found lying in the roadway. No witnesses were pres- ent, and the police had no leads regarding the suspect vehicle. A gold metallic painted plastic fragment recovered from the scene and the victim’s clothing were submitted to the Virginia Department of Forensic Science for analysis.

The victim’s clothing was scraped, and several minute gold metallic paint particles were recovered. Most of these particles contained only topcoats, whereas one minute particle contained two primer layers and a limited amount of colorcoat. The color of the primer surface layer was similar to that typi- cally associated with some Fords. Subsequent spectral searches in the Paint Data Query (PDQ) database indicated that the paint most likely originated from a 1990 or newer Ford.

The most discriminating aspect of this paint was the unusual-looking gold metallic topcoat color. A search of au- tomotive repaint books yielded only one color that closely

matched the paint recovered in the case. The color, Aztec Gold Metallic, was determined to have been used only on 1997 Ford Mustangs.

The results of the examination were relayed via telephone to the investigating detective. The investigating detective quickly determined that only 11,000 1997 Ford Mustangs were produced in Aztec Gold Metallic. Only two of these vehicles were registered, and had been previously stopped, in the juris- diction of the offense. Ninety minutes after the make, model, and year information was relayed to the investigator, he called back to say he had located a suspect vehicle. Molding from the vehicle and known paint samples were submitted for com- parison. Subsequent laboratory comparisons showed that the painted plastic piece recovered from the scene could be physi- cally fitted together with the molding, and paint recovered from the victim’s clothing was consistent with paint samples taken from the suspect vehicle.

Source of data: Based on information obtained from Brenda Christy, Virginia Department of Forensic Science

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FIGURE 3–8 The crime-scene footwear print on the right is being searched against eight thousand sole patterns to determine its make and model.

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review questions

Physical evidence is usually examined by a forensic scientist for identification or comparison purposes. The object of iden- tification is to determine the physical or chemical identity with as near absolute certainty as existing analytical techniques will permit. Identification first requires the adoption of testing procedures that give characteristic results for specific standard materials. Once this is done, the examiner uses an appropriate number of tests to identify a substance and exclude all other substances from consideration. The identification process is normally used in crime laboratories to identify drugs, explo- sives, and petroleum products. Also, evidence such as blood, semen, or hair is routinely identified in a crime laboratory. Normally, these identifications would include a determination for species origin (such as human blood or rabbit hair).

A comparative analysis has the important role of deter- mining whether a suspect specimen and a standard/reference specimen have a common origin. Both the standard/ reference specimen and the suspect specimen are subject to the same tests. Evidence that can be associated with a common source with an extremely high degree of probability is said to possess individual characteristics. Evidence associated only with a group is said to have class characteristics. Nevertheless, the high diversity of class evidence in our environment makes their comparison significant in the context of a criminal

investigation. As the number of different objects linking an individual to a crime scene increases, so does the likelihood of that individual’s involvement with the crime. Importantly, a person may be exonerated or excluded from suspicion if phys- ical evidence collected at a crime scene is found to be different from standard/reference samples collected from that subject.

A dramatic enhancement of the role of forensic science in criminal investigation has come about through the creation of computerized databases. The Integrated Automated Fin- gerprint Identification System (IAFIS), a national fingerprint and criminal history system, is maintained by the FBI. The FBI’s Combined DNA Index System (CODIS) enables fed- eral, state, and local crime laboratories to electronically ex- change and compare DNA profiles, thereby linking crimes to each other and to convicted offenders. The National Integrated Ballistics Information Network (NIBIN), maintained by the Bureau of Alcohol, Tobacco, Firearms and Explosives, allows firearms analysts to acquire, digitize, and compare markings made by a firearm on bullets and cartridge casings recovered from crime scenes. The International Forensic Automotive Paint Data Query (PDQ) database contains chemical and color information pertaining to original automotive paints. SICAR (shoeprint image capture and retrieval) has a comprehensive shoe sole database.

chapter summary

1. The process of _____ determines a substance’s physical or chemical identity with as near absolute certainty as existing analytical techniques will permit.

2. The number and type of tests needed to identify a sub- stance must be sufficient to _____ all other substances from consideration.

3. A(n) _____ analysis subjects a suspect specimen and a standard/reference specimen to the same tests and ex- amination in order to determine whether they have a common origin.

4. _____ is the frequency of occurrence of an event.

5. Evidence that can be traced to a common source with an extremely high degree of probability is said to possess _____ characteristics.

6. Evidence associated with a group and not with a single source is said to possess _____ characteristics.

7. True or False: One of the major deficiencies of forensic science is the inability of the examiner to assign exact or approximate probability values to the comparison of most class physical evidence. _____

8. The value of class physical evidence lies in its ability to _____ events with data in a manner that is, as nearly as possible, free of human error and bias.

9. The _____ accorded physical evidence during a trial is left entirely to the trier of fact.

10. Although databases are consistently updated so that sci- entists can assign probabilities to class evidence, for the most part, forensic scientists must rely on _____ when interpreting the significance of class physical evidence.

11. The believability of _____ accounts, confessions, and in- formant testimony can all be disputed, maligned, and sub- jected to severe attack and skepticism in the courtroom.

12. True or False: Physical evidence cannot be used to ex- clude or exonerate a person from suspicion of commit- ting a crime. _____

13. True or False: The distinction between individual and class evidence is always easy to make. _____

14. True or False: Given the potential weight of scien- tific evidence in a trial setting, failure to take proper

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PHYSICAL EVIDENCE 73

application and critical thinking

1. Arrange the following tasks in order from the one that would require the least extensive testing procedure to the one that would require the most extensive. Explain your answer.

a. Determining whether an unknown substance contains an illicit drug

b. Determining the composition of an unknown substance

c. Determining whether an unknown substance con- tains heroin

2. The following are three possible combinations of DNA characteristics that may be found in an individual’s ge- netic profile. Using the product rule, rank each of these combinations of DNA characteristics from most com- mon to least common. The number after each char- acteristic indicates its percentage distribution in the population.

a. FGA 24,24 (3.6%), TH01 6,8 (8.1%), and D16S539 11,12 (8.9%)

b. vWA 14,19 (6.2%), D21S11 30,30 (3.9%), and D13S317 12,12 (8.5%)

c. CSF1PO 9,10 (11.2%), D18S51 14,17 (2.8%), and D8S1179 17,18 (6.7%)

3. For each of the following pieces of evidence, indicate whether the item is more likely to possess class or indi- vidual characteristics and explain your answers.

a. An impression from a new automobile tire

b. A fingerprint

c. A spent bullet cartridge

d. A mass-produced synthetic fiber

e. Pieces of a shredded document

f. Commercial potting soil

g. Skin and hair scrapings

h. Fragments of a multilayer custom automobile paint

4. Which of the forensic databases described in the text contain information that relates primarily to evidence exhibiting class characteristics? Which ones contain in- formation that relates primarily to evidence exhibiting individual characteristics? Explain your answers.

5. An investigator at a murder scene notes signs of a pro- longed struggle between the attacker and victim. Name at least three types of physical evidence for which the investigator would probably collect standard/reference samples, and explain why he or she would collect them.

safeguards may unfairly prejudice a case against the suspect. _____

15. Students studying forensic science must be cautioned that merely reading relevant textbooks and journals is no substitute for _____ in this most practical of sciences.

16. Modern analytical techniques have become so sensitive that the forensic examiner must be aware of the _____ among materials when interpreting the significance of comparative data.

17. True or False: A fingerprint can be positively identified through the IAFIS database. _____

18. A database applicable to DNA profiling is _____.

19. The _____ database allows firearm analysts to compare markings made by firearms on bullets that have been recovered from crime scenes.

20. The _____ database contains chemical and color infor- mation pertaining to original automotive paints.

further references

Houck, M. M., “Statistics and Trace Evidence: The Tyranny of Numbers,” Forensic Science Communications 1, no. 3 (1999), http://www.fbi.gov/about-us/lab/forensic-science- communications/fsc/oct1999/houck.htm

Houck, M. M., and J. A. Siegel, Fundamentals of Forensic Science, 2nd ed. Burlington, Mass.: Elsevier Academic Press, 2011.

Osterburg, James W., “The Evaluation of Physical Evidence in Criminalistics: Subjective or Objective Process?” Journal of Criminal Law, Criminology and Police Science 60 (1969): 97.

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The Sam Sheppard Case: A Trail of Blood

Convicted in 1954 of bludgeoning his wife to death, Dr. Sam Sheppard achieved celebrity status when the storyline of TV’s The Fugitive was apparently modeled on his efforts to seek vindication for the crime he professed not to have committed. Dr. Sheppard, a physician, claimed he was dozing on his living room couch when his pregnant wife, Marilyn, was attacked. Sheppard’s story was that he quickly ran upstairs to stop the carnage but was knocked unconscious briefly by the intruder. The suspicion that fell on Dr. Sheppard was fueled by the revelation that he was having an adulterous affair. At trial, the local coroner testified that a pool of blood on Marilyn’s pillow contained the impression of a “surgical instrument.” After Sheppard had been imprisoned for ten years, the U.S. Supreme Court set aside his conviction because of the “massive, pervasive, and prejudicial publicity” that had attended his trial.

In 1966, the second Sheppard trial commenced. This time, the same coroner was forced to back off from his insistence that the bloody outline of a surgical instrument was present on Marilyn’s

pillow. However, a medical technician from the coroner’s office now testified that blood on

Dr. Sheppard’s watch was from blood spatter, indicating that Dr. Sheppard was wearing the watch in the presence of the battering of his

wife. The defense countered with the expert testimony of eminent criminalist Dr. Paul Kirk. Dr. Kirk concluded that blood spatter marks in the bedroom showed the killer to be

left-handed. Dr. Sheppard was right-handed. Dr. Kirk further testified that Sheppard stained his watch while attempting to obtain a pulse reading.

After less than 12 hours of deliberation, the jury failed to convict Sheppard. But the ordeal had taken its toll. Four years later Sheppard died, a victim of drug and alcohol abuse.

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After studying this chapter you should be able to: Define crime-scene reconstruction

Discuss the information that can be gained from bloodstain pattern analysis about the events involved in a violent crime

Explain how surface texture, directionality, and angle of impact affect the shape of individual bloodstains

Calculate the angle of impact of a bloodstain using its dimensions

Describe the classifications of low-, medium-, and high-velocity impact spatter and appreciate how cautiously these classifica- tions should be used

Discuss the methods to determine the area of convergence and area of origin for impact spatter patterns

Understand how various blood pattern types are created and which features of each pattern can be used to aid in recon- structing events at a crime scene

Describe the methods for documenting bloodstain patterns at a crime scene

crime-scene reconstruction: bloodstain pattern analysis angle of impact

area of convergence area of origin arterial spray back spatter cast-off crime-scene

reconstruction drip trail pattern expirated blood

pattern flows forward spatter high-velocity spatter impact spatter low-velocity spatter medium-velocity

spatter satellite spatter skeletonization transfer pattern void

KEY TERMS

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76 CHAPTER 4

Crime-Scene Reconstruction Principles of Crime-Scene Reconstruction Previous discussions dealing with the processes of identification and comparison have stressed laboratory work routinely performed by forensic scientists. However, there is another dimension to the role that forensic scientists play during the course of a criminal investigation: participating in a team effort to reconstruct events that occurred before, during, and after the commission of a crime.

Law enforcement personnel must take proper action to enhance all aspects of the crime-scene search so as to optimize the crime-scene reconstruction. First, and most important, is securing and protecting the crime scene. Protecting the scene is a continuous endeavor from the beginning to the end of the search. Evidence that can be invaluable to reconstructing the crime can be unknowingly altered or destroyed by people trampling through the scene, rendering the evidence useless. The issue of possible contamination of evidence will certainly be attacked during the litigation process and could make the difference between a guilty and not-guilty verdict.

Before processing the crime scene for physical evidence, the investigator should make a pre- liminary examination of the scene as it was left by the perpetrator. Each crime scene presents its own set of circumstances. The investigator’s experience and the presence or absence of physical evidence become critical factors in reconstructing a crime. The investigator captures the nature of the scene as a whole by performing an initial walk-through of the crime scene and contemplating the events that took place. Using the physical evidence available to the naked eye, he or she can hy- pothesize about what occurred, where it occurred, and when it occurred. During the walk-through, the investigator’s task is to document observations and formulate how the scene should ultimately be processed. As the collection of physical evidence begins, any and all observations should be recorded through photographs, sketches, and notes. By carefully collecting physical evidence and thoroughly documenting the crime scene, the investigator can begin to unravel the sequence of events that took place during the commission of the crime.

Personnel Involved in Reconstruction Because investigators consider many types of evidence when reconstructing a crime scene, re- construction is a team effort that involves various professionals putting together many pieces of a puzzle. The team as a whole works to answer the typical “who, what, when, where, why, and how” of a crime scene. Often reconstruction requires the involvement of law enforcement personnel, a medical examiner, and/or a criminalist. All of these professionals contribute unique perspectives to develop the crime-scene reconstruction. Was more than one person involved? How was the victim killed? Were actions taken to cover up what took place? The positioning of the victim in a crime scene can often reveal pertinent information for the investigation. Trained medical examiners can examine the victim at a crime scene and determine whether the body has been moved after death by evaluating the livor distribution within the body (see page 109). For example, if livor has developed in areas other than those closest to the ground, the medical examiner can reason that the victim was probably moved after death. Likewise, the examiner can determine whether the victim was clothed after death because livor will not develop in areas of the body that are restricted by clothing.

A criminalist or trained crime-scene investigator can also bring special skills to the recon- struction of events that occurred during the commission of a crime. For example, a criminalist using a laser beam to plot the approximate bullet path in trajectory analysis can help determine the probable position of the shooter relative to that of the victim (see Figure 4–1). Other skills that a criminalist may employ during a crime-scene reconstruction analysis include determining the direction of impact of projectiles penetrating glass objects (see page 223); locating gunshot residues deposited on the victim’s clothing for the purpose of estimating the distance of a shooter from a target (see pages 180–182); searching for primer residues deposited on the hands of a sus- pect shooter (see pages 183–186); and, as we will see from the discussion that follows, analyzing blood spatter patterns.

Crime-scene reconstruction is the method used to support a likely sequence of events at a crime scene by observing and evaluating physical evidence and statements made by individuals involved with the incident. The evidence may also include information obtained from reenact- ments. Therefore, reconstructions have the best chance of being accurate when investigators use proper documentation and collection methods for all types of evidence.

crime-scene reconstruction The method used to support a likely sequence of events at a crime scene by the observation and evaluation of physical evidence and statements made by individuals involved with the incident.

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CRIME-SCENE RECONSTRUCTION: BLOODSTAIN PATTERN ANALYSIS 77

Physical evidence left behind at a crime scene plays a crucial role in reconstructing the sequence of events surrounding the crime. Although the evidence alone may not describe every- thing that happened, it can support or contradict accounts given by witnesses and/or suspects. Information obtained from physical evidence can also generate leads and confirm the reconstruc- tion of a crime to a jury. The collection, documentation, and interpretation of physical evidence is the foundation of a reconstruction. Reconstruction develops a likely sequence of events by the observation and evaluation of physical evidence as well as statements made by witnesses and input from those involved with the investigation of the incident. Analysis of all available data will help to create a workable model for reconstruction.

General Features of Bloodstain Formation Crimes involving violent contact between individuals are frequently accompanied by bleeding and resultant bloodstain patterns. Crime-scene analysts have come to appreciate that bloodstain patterns deposited on floors, walls, ceilings, bedding, and other relevant objects can provide valu- able insights into events that occurred during the commission of a violent crime. The information one is likely to uncover as a result of bloodstain pattern interpretation includes the following:

The crime-scene investigator must not overlook the fact that the location, distribution, and ap- pearance of bloodstains and spatters may be useful for interpreting and reconstructing the events that accompanied the bleeding. A thorough analysis of the significance of the position and shape of blood patterns with respect to their origin and trajectory is exceedingly complex and requires the ser- vices of an examiner who is experienced in such determinations. Most important, the interpretation of bloodstain patterns necessitates a carefully planned control experiment using surface materials comparable to those found at the crime scene. This chapter presents the basic principles and com- mon deductions behind bloodstain pattern analysis to give the reader general knowledge to use at the crime scene.

Surface Texture Surface texture is of paramount importance in the interpretation of bloodstain patterns; com- parisons between standards and unknowns are valid only when identical surfaces are used.

Bullet entrance wound

Search path for evidence of shooter

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FIGURE 4–1 A laser beam is used to determine the search area for the position of a shooter who has fired a bullet through a window and wounded a victim. The bullet path is determined by lining up the victim’s bullet wound with the bullet hole present in the glass pane.

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78 CHAPTER 4

In general, harder and nonporous surfaces (such as glass or smooth tile) result in less spatter. Rough surfaces, such as a concrete floor or wood, usually result in irregularly shaped stains with serrated edges, possibly with satellite spatter (see Figure 4–2).

Direction and Angle of Impact An investigator may discern the direction of travel of blood that struck an object by studying the stain’s shape. As the stain becomes more elliptical in shape, its direction becomes more discern- ible because the pointed end of a bloodstain faces its direction of travel. The distorted or disrupted edge of an elongated stain indicates the direction of travel of the blood drop. Satellite spatter around parent stains will have the pointed end facing against the direction of travel. In Figure 4–3,

satellite spatter Small drops of blood that are distributed around the perimeter of a drop or drops of blood and were produced as a result of the blood impacting the target surface.

FIGURE 4–2 (a) A bloodstain from a single drop of blood that struck a glass surface after falling 24 inches. (b) A bloodstain from a single drop of blood that struck a cotton muslin sheet after falling 24 inches. (b)

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FIGURE 4–3 A bloodstain pattern produced by drops of blood that were traveling from left to right.

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CRIME-SCENE RECONSTRUCTION: BLOODSTAIN PATTERN ANALYSIS 79

angle of impact The acute angle formed between the path of a blood drop and the surface that it contacts.

FIGURE 4–4 The higher pattern is of a single drop of human blood that fell 24 inches and struck hard, smooth cardboard at 50 degrees. On this drop the collection of blood shows the direction. The lower pattern is of a single drop of hu- man blood that fell 24 inches and struck hard, smooth cardboard at 15 degrees. On this drop the tail shows the direction.

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the bloodstain pattern was produced by several drops of blood that were traveling from left to right before striking a flat, level surface.

It is possible to determine the impact angle of blood on a flat surface by measuring the degree of circular distortion of the stain. A drop deposited at an angle of impact of about 90 degrees (directly vertical to the surface) will be approximately circular in shape with no tail or buildup of blood. However, as the angle of impact deviates from 90 degrees, the stain becomes elongated in shape. Buildup of blood will occur when the angles are larger, whereas longer and longer tails will appear as the angle of impact becomes smaller (see Figure 4–4).

Impact Bloodstain Spatter Patterns The most common type of bloodstain pattern found at a crime scene is impact spatter. This pat- tern occurs when an object impacts the source of the blood. Spatter projected outward and away from the source, such as an exit wound, is called forward spatter. Back spatter, sometimes called blow-back spatter, is blood projected backward from a source, such as an entrance wound, and potentially deposited on the object or person who created the impact. Impact spatter patterns consist of many drops radiating in direct lines from the origin of blood to the stained surface (see Figure 4–5).

Investigators have derived a common classification system of impact spatter based on the velocity of the force impacting on a bloody object. In general, as the velocity of the force of the impact on the source of blood increases, so does the velocity of the blood drops emanating from the source. It is also generally true that, as both the force and velocity of impact increase, the diameter of the resulting blood drops decreases.

WEBEXTRA 4.1 See How Bloodstain Spatter Patterns Are Formed

impact spatter A bloodstain pattern produced when an object makes forceful contact with a source of blood, projecting drops of blood outward from the source.

forward spatter Blood that travels away from the source in the same direction as the force that caused the spatter.

back spatter Blood directed back toward the source of the force that caused the spatter.IS

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80 CHAPTER 4

For example, suppose the width of a stain is 11 mm and the length is 22 mm.

sin A = 11 mm 22 mm

= 0.50

A scientific calculator with trigonometric functions will calculate that a sine of 0.50 corresponds to a 30-degree angle.

Note: The measurements for length and width should be made with a ruler, micrometer, or photographic loupe.

Determining the Angle of Impact of Bloodstains

The distorted or disrupted edge of an elongated stain indicates the direction of travel of the blood drop. One may establish the location or origin of bloodshed by determining the directionality of the stain and the an- gle at which blood came into contact with the landing surface. To determine the angle of impact, calculate the stain’s length-to-width ratio and apply the formula

sin A = width of blood stain length of blood stain

where A = the angle of impact.

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FIGURE 4–5 Impact spatter produced by an automatic weapon. The arrows shows multiple direction of travel for skull fragments emanating from the gunshot.

low-velocity spatter An impact spatter pattern cre- ated by a force traveling at 5 feet per second or less and producing drops with diameters greater than 3 millimeters.

medium-velocity spatter An impact spatter pattern created by a force traveling at 5 to 25 feet per second and producing drops with diameters between 1 and 3 millimeters.

high-velocity spatter An impact spatter pattern created by a force traveling at 100 feet per second or faster and producing drops with diameters less than 1 millimeter.

Classifying Impact Spatter LOW-VELOCITY SPATTER An impact pattern consisting of a preponderance of large separate or compounded drops with diameters of 4 millimeters or more is known as low-velocity spatter. This kind of spatter is normally produced by gravity alone, by a minimal force, or by an object dropping into and splashing blood from a blood pool. Low-velocity stains can result from an applied force moving at up to 5 feet per second.

MEDIUM-VELOCITY SPATTER A pattern predominantly consisting of small drops with diameters of 1 to 4 millimeters is classified as medium-velocity spatter. This type of impact spatter is normally associated with blunt-force trauma to an individual or with other applied forces moving at between 5 to 25 feet per second.

HIGH-VELOCITY SPATTER Very fine drops with a preponderance of diameters of less than 1 millimeter are classified as high-velocity spatter. Here the spatter can result from an applied force of 100 feet per second or faster. Gunshot exit wounds or explosions commonly produce this

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type of spatter. However, because the drops are very small, they may not travel far; they may fall to the floor or ground, where investigative personnel could overlook them.

Using droplet size to classify impact patterns by velocity is a useful tool that gives inves- tigators insight into the general nature of a crime. However, the classifications of low, me- dium, and high velocity cannot illuminate the specific events that produced the stain pattern. For example, beatings can produce either high-velocity spatter or stain sizes that look more like low-velocity spatter. In general, one should use stain size categories very cautiously, and for descriptive purposes only, in evaluating impact spatter patterns. A more acceptable approach for classifying a bloodstain pattern should encompass observations of stain size, shape, location, and distribution.

Blood spatter patterns can arise from a number of distinctly different sources, which will be discussed in this chapter. Illustrations of patterns emanating from impact, cast-off, and arterial spray are shown in Figure 4–6.

FIGURE 4–6 (a) The action associated with producing impact spatter. (b) The action associated with producing cast-off spatter. (c) The action associated with producing arterial spurt spatter.

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Convergence

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FIGURE 4–7 An illustration of stain convergence on a two-dimensional plane. Convergence represents the area from which the stains emanated.

Origin of Impact Patterns Impact spatter patterns can offer investigators clues about the origin of the blood spatter and, therefore, the position of the victim at the time of the impact.

AREA OF CONVERGENCE The area of convergence is the point on a two-dimensional plane from which the drops originated. This can be established by drawing straight lines through the long axis of several individual bloodstains, following the line of their tails. The intersection of these lines is the area of convergence, and the approximate point of origin will be on a line straight out from this area. Figure 4–7 illustrates how to draw lines to find an area of convergence.

An object hitting a source of blood numerous times will never produce exactly the same pattern each time. One can therefore determine the number of impacts by drawing the area of convergence for groups of stains from separate impacts.

AREA OF ORIGIN It may also be important to determine the area of origin of a bloodstain pattern, the area in a three-dimensional space from which the blood was projected. This will show the position of the victim or suspect in space when the stain-producing event took place. The distribution of the drops in an impact pattern gives a general idea of the distance from the blood source to the bloodstained surface. Impact patterns produced at a distance close to the surface will appear as clustered stains. As the distance from the surface increases, so do the distribution and distance between drops.

A common method for determining the area of origin at the crime scene is called the string method. Figure 4–8 illustrates the steps in the string method:

1. Find the area of convergence for the stain pattern. 2. Place a pole or stand as an axis coming from the area of convergence. 3. Attach one end of a string next to each droplet. Place a protractor next to each droplet and

lift the string until it lines up with the determined angle of impact of the drop. Keeping the string in line with the angle, attach the other end of the string to the axis pole.

4. View the area of origin of the drops where the strings appear to meet. Secure the strings at this area.

area of convergence The area on a two-dimensional plane where lines traced through the long axis of several individual bloodstains meet; this approxi- mates the two-dimensional place from which the bloodstains were projected.

area of origin The location in three-dimensional space from which blood that pro- duced a bloodstain originated; the location of the area of convergence and the angle of impact for each bloodstain is used to approximate this area.

WEBEXTRA 4.2 Blood Stain Analysis: Calculating the Area of Convergence and Origin

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More Bloodstain Spatter Patterns Gunshot Spatter A shooting may leave a distinct gunshot spatter pattern. This may be characterized by both forward spatter from an exit wound and back spatter from an entrance wound. The presence of back spatter on a firearm or a shooter is dependent on the distance between the firearm and victim. Forward spatter generally leaves a pattern of very fine drops characteristic of high-velocity spatter (see Figure 4–9). Medium- and large-sized drops may also be observed within the spatter pattern.

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FIGURE 4–8 An illustration of the string method used at a crime scene to determine the area of origin of impact blood spatter.

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The location of injury, the size of the wound created, and the distance between the vic- tim and the muzzle of the weapon all affect the amount of back spatter that occurs. Finding high- velocity spatter containing the victim’s blood on a suspect can help investigators place the suspect in the vicinity when the gun was discharged. Back spatter created by a gunshot impact generally contains fewer and smaller, atomized stains than does forward spatter. Muzzle blast striking an entrance wound will cause the formation of atomized blood.

Depending on the distance from the victim at which the gun was discharged, some back spat- ter may strike the gunman and enter the gun muzzle. This is called the drawback effect. Blood within the muzzle of a gun can “place” the weapon in the vicinity of the gunshot wound. The presence of blow-back spatter on a weapon’s muzzle is consistent with the weapon’s having been close to the victim at the time of firing.

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FIGURE 4–9 An impact spatter pattern emanating from a bullet striking a blood source (in this case a sponge) before passing through a card- board target. Mist comes from the muzzle blast, not from the bullet impacting the blood source.

Blood-Spatter Evidence Stephen Scher banged on the door of a cabin in the woods outside Montrose, Pennsylvania. According to Scher, his friend, Marty Dillon, had just shot himself while chasing af- ter a porcupine. The two had been skeet shooting at Scher’s cabin, enjoying a friendly sporting weekend, when Dillon spotted a porcupine and took off out of sight. Scher heard a single shot and waited to hear his friend’s voice. After a few moments, he chased after Dillon and found him lying on the ground near a tree stump, bleeding from a wound in his chest. Scher administered CPR after locating his dying friend, but he was unable to save Dillon, who later died from his injuries. Police found that Dillon’s untied boot had been the cause of his shotgun wound. They determined that he had tripped while running with his loaded gun and shot himself. The grief-stricken Scher aroused no suspicion, so the shoot- ing was ruled an accident.

Shortly thereafter, Scher moved from the area, divorced his wife, and married Dillon’s widow. This was too suspi- cious to be ignored; police reopened the case and decided to

reconstruct the crime scene. The reconstruction provided in- vestigators with several pieces of blood evidence that pointed to Scher as Dillon’s murderer.

Police noticed that Scher’s boots bore the unmistakable spray of high-velocity impact blood spatter, evidence that he was standing within an arm’s length of Dillon when Dillon was shot. This pattern of bloodstains would not be expected to be created while administering CPR, as Scher claimed had hap- pened. The spatter pattern also clearly refuted Scher’s claim that he did not witness the incident. In addition, the tree stump near Dillon’s body bore the same type of blood spatter, in a pattern that indicated Dillon was seated on the stump and not running when he was shot. Finally, Dillon’s ears were free of the high-velocity blood spatter that covered his face, but blood was on his hearing protectors found nearby. This is a clear in- dication that he was wearing his hearing protectors when he was shot and they were removed before investigators arrived. This and other evidence resulted in Scher’s conviction for the murder of his longtime friend, Marty Dillon.

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Cast-Off Spatter A cast-off pattern is created when a blood-covered object flings blood in an arc onto a nearby surface. This kind of pattern commonly occurs when a person pulls a bloody fist or weapon back between delivering blows to a victim (see Figure 4–6[b]). The bloodstain tails will point in the direction that the object was moving.

The width of the cast-off pattern created by a bloody object may help suggest the kind of object produced by the pattern. The sizes of the drops are directly related to the size of the point from which they were propelled. Drops propelled from a small or pointed surface will be smaller and the pattern more linear; drops propelled from a large or blunt surface will be larger and the pattern wide. The volume of blood deposited on an object from the source also affects the size and number of drops in the cast-off pattern. The less blood on the object, the smaller the stains produced. The pattern may also suggest whether the blow that caused the pattern was directed from right to left or left to right. The pattern will point in the direction of the backward thrust, which will be opposite the direction of the blow. This could suggest which hand the assailant used to deliver the blows.

Cast-off patterns may also show the minimum number of blows delivered to a victim. Each blow should be marked by an upward-and-downward or forward-and-backward arc pattern (see Figure 4–10). By counting and pairing the patterns, one can estimate the minimum number of blows. An investigator should take into consideration that the first blow would only cause blood to pool to the area; it would not produce a cast-off pattern. Also, some blows may not come into contact with blood and therefore will not produce a pattern. The medical examiner is in the best position to estimate the number of blows a victim received.

Arterial Spray Spatter Arterial spray spatter is created when a victim suffers an injury to a main artery or the heart. The pressure of the continuing pumping of blood causes blood to spurt out of the injured area (see Figure 4–6[c]). Commonly, the pattern shows large spurted stains for each time the heart pumps. Some radial spikes, satellite spatter, or flow patterns may be evident because of the large volume of blood being expelled with each spurt. Drops may also be seen on the surface in fairly uniform size and shape and in parallel arrangement (see Figure 4–11).

cast-off A bloodstain pattern that is created when blood is flung from a blood- bearing object in motion onto a surface.

arterial spray A characteristic bloodstain pattern containing spurts that resulted from blood exiting under pressure from an arterial injury.

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FIGURE 4–10 Swing was upper right to lower left. Return to position for the next blow was short swing at left. Cast offs depend entirely on the weapon’s abil- ity to acquire and hold blood, how the swing is achieved, and where in space the victim is located for the blows to be struck.

FIGURE 4–11 Arterial spray spatter found at a crime scene where a victim suf- fered injury to an artery.

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The lineup of the stains shows the victim’s movement. Any vertical arcs or waves in the line show fluctuations in blood pressure. The larger arterial stains are at the end of the overall pattern. The site of the initial injury to the artery can be found where the pattern begins with the biggest spurt. Arterial patterns can also be differentiated because the oxygenated blood spurting from the artery tends to be a brighter red color than blood expelled from impact wounds.

Expirated Blood Patterns A pattern created by blood that is expelled from the mouth or nose from an internal injury is called an expirated blood pattern. If the blood that creates such a pattern is under great pressure, it produces very fine high-velocity spatter. Expirated blood at very low velocities produces a stain cluster with irregular edges (see Figure 4–12). The presence of bubbles of oxygen in the drying drops can differentiate a pattern created by expirated blood from other types of bloodstains. Expi- rated blood also may be lighter in color than impact spatter as a result of being diluted by saliva. The presence of expirated blood gives an important clue to the injuries suffered and the events that took place at a crime scene.

Void Patterns A void is created when an object blocks the deposition of blood spatter onto a surface or object (see Figure 4–13). The spatter is deposited onto the object or person instead. The blank space on the surface or object may give a clue to the size and shape of the missing object or person. Once the object or person is found, the missing piece of the pattern should fit in, much like a puzzle piece, with the rest of the pattern. Voids may help establish the body position of the victim or assailant at the time of the incident.

Other Bloodstain Patterns Not all bloodstains at a crime scene appear as spatter patterns. The circumstances of the crime often create other types of stains that can be useful to investigators.

FIGURE 4–12 An example of blood expelled with two wheezes from the mouth.

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expirated blood pattern A pattern created by blood that is expelled out of the nose, mouth, or respiratory system as a result of air pressure and/or airflow.

void An area within a deposited spat- ter pattern that is clear of spatter, caused by an object or person blocking the area at the time of the spatter’s deposition.

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Contact/Transfer Patterns When an object with blood on it touches another object that did not have blood on it, this pro- duces a contact or transfer pattern. Examples of transfers with features include fingerprints (see Figure 4–14), handprints, footprints, footwear prints, tool prints, and fabric prints in blood. These may provide further leads by offering individual characteristics.

The size and general shape of a tool may be seen in a simple transfer. This can lead to nar- rowing the possible tools by class characteristics. A transfer that shows a very individualistic feature may help point to the tool that made the pattern.

Simple transfer patterns are produced when the bloody object makes contact with a surface and the object is removed without any further movement. Other transfers known as swipe patterns may be caused by movement of the bloody object across a surface. Generally, the pattern will lighten and “feather” as the pattern moves away from the initial contact point (see Figure 4–15). However, because “feathering” is also a function of the amount of pressure being applied to the surface, the analyst must interpret directionality with care. The direction of separate bloody transfers, such as footwear prints in blood, may show the movement of the suspect, victim, or others through the crime scene after the blood was present. The first transfer pattern will be dark and heavy with blood, whereas subsequent transfers will be increasingly lighter in color. The transfers get lighter as less and less blood is deposited from the transferring object’s surface. Bloody shoe imprints may also suggest whether the wearer was running or walking. Running typically produces imprints with more space between them and more satellite or drop patterns between each imprint.

Flows Patterns made by drops or large amounts of blood flowing with the pull of gravity are called flows. Flows may be formed by single drops or large volumes of blood coming from an actively bleeding wound or blood deposited on a surface—from an arterial spurt, for example. Clotting of the blood’s solid parts may occur when a flow extends onto an absorbent surface.

The flow direction may show movements of objects or bodies while the flow was still in progress or after the blood had dried. Figure 4–16 illustrates a situation in which movement of the surface while the flow was still in progress led to a specific pattern.

Interruption of a flow pattern may be helpful in assessing the sequence and passage of time between the flow and its interruption. If a flow found on an object or body does not appear to be

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FIGURE 4–13 A void pattern is found behind the door where the surface of the door blocked the deposition of spatter on that area. This void, and the presence of spatter on the door, shows that the door was open when the spatter was deposited.

transfer pattern A bloodstain pattern created when a surface that carries wet blood comes in contact with a second surface; recognizable imprints of all or a portion of the original surface or the direction of movement may be observed.

flow A bloodstain pattern formed by the movement of small or large amounts of blood as a result of gravity’s pull.

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FIGURE 4–14 A transfer pattern consisting of bloody fingerprints with apparent ridge detail.

consistent with the direction of gravity, one may surmise that the object or body was moved after the blood had dried.

Pools A pool of blood occurs when blood collects in a level (not sloped) and undisturbed place. Blood that pools on an absorbent surface may be absorbed throughout the surface and diffuse, creating a pattern larger than the original pool. This often occurs to pools on beds or sofas.

The approximate drying time of a pool of blood is related to the environmental condition of the scene. By experimentation, an analyst may be able to reasonably estimate the drying times of stains of different sizes. Small and large pools of blood can be helpful in reconstruction because they can be analyzed to estimate the amount of time that has elapsed since the blood was depos- ited. Considering the drying time of a blood pool can yield information about the timing of events that accompanied the incident.

The edges of a stain will dry to the surface, producing a phenomenon called skeletonization (see Figure 4–17). This usually occurs within 50 seconds of deposition for drops, and it takes longer for larger volumes of blood. If the central area of the pooled bloodstain is then al- tered by wiping, the skeletonized perimeter will be left intact. This can be used to interpret whether movement or activity occurred shortly after the pool was deposited or later, after the perimeter had time to skeletonize first. This may be important for classifying the source of the original stain.

skeletonization The process by which the edges of a stain dry to the surface in a specific period of time (dependent on environmental and surface con- ditions); skeletonization remains apparent even after the rest of the bloodstain has been disturbed from its original position.

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FIGURE 4–15 A series of swipe patterns moving from right to left.

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FIGURE 4–16 The flow pattern suggests that the victim was upright and then fell while blood flowed. The assailant claimed the victim was stabbed while sleeping.

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FIGURE 4–17 Skeletonization is shown in a bloodstain that was dis- turbed after the edges had time to skeletonize.

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Drip Trail Patterns A drip trail pattern is a series of drops that is separate from other patterns, and it is formed by blood dripping off an object or injury. The stains form a kind of line, usually the path made by the suspect after injuring or killing the victim. It may simply show movement, lead to a discarded weapon, or provide identification of the suspect if it is made from his or her own blood. Inves- tigators often see this type of pattern in stabbings during which the criminal inadvertently cuts himself or herself as a result of using the force necessary to stab the victim. Figure 4–18 shows a drop trail pattern away from the center of action at a crime scene.

The shape of the stains in a drip trail pattern can help investigators determine the direction and speed at which a person was moving. The tails of the drops in a trail pattern point in the direc- tion the person was moving. More circular stains are found where the person was moving slowly. This information may be helpful in reconstruction.

Documenting Bloodstain Pattern Evidence Blood spatter patterns of any kind can provide a great deal of information about the events that took place at a crime scene. For this reason, investigators should note, study, and photograph each pattern and drop. This must be done to accurately record the location of specific patterns and to distinguish the stains from which laboratory samples were taken. The photographs and sketches can also point out specific stains used in determining the direction of force, angle of impact, and area of origin.

drip trail pattern A pattern of bloodstains formed by the dripping of blood off a moving surface or person in a recogniz- able pathway separate from other patterns.

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FIGURE 4–18 A drip trail pattern leads away from the center of the mixed bloodstain pattern.

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Just as in general crime-scene photography, the investigator should create photographs and sketches of the overall pattern to show the orientation of the pattern to the scene. The medium- range documentation should include pictures and sketches of the whole pattern and the relation- ships between individual stains within the pattern. The close-up photographs and sketches should show the dimensions of each individual stain. Close-up photographs should be taken with a scale of some kind showing in the photograph.

Two common methods of documenting bloodstain patterns place attention on the scale of the patterns. The grid method involves setting up a grid of squares of known dimensions over the entire pattern using string and stakes (see Figure 4–19). All overall, medium-range, and close-up photographs are taken with and without the grid. The second method, called the perimeter ruler method, involves setting up a rectangular border of rulers around the pattern. In this method, the large rulers show scale in the overall and medium-range photos, whereas the small rulers can be inserted to show scale in the close-up photographs (see Figure 4–20). Some investigation teams use tags in close-up photographs to show evidence numbers or other details.

An area-of-origin determination may be calculated at the discretion of the bloodstain analyst when the circumstances of the case warrant such a determination. All measurements of stains and calculations of angle of impact and point of origin should be recorded in crime-scene notes. Especially important stains can be roughly sketched within the notes.

Only some jurisdictions have a specialist on staff to decipher patterns either at the scene or from photographs at the lab. Therefore, it is important that all personnel be familiar with patterns to properly record and document them for use in reconstruction.

String grid - Two-foot squares

= Lettered or numbered label in each square

FIGURE 4–19 The grid method may be used for photo- graphing bloodstain pattern evidence.

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FIGURE 4–20 The perimeter ruler method may be used for photographing bloodstain pattern evidence.

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Bloodstain Reconstruction An elderly male was found lying dead on his living room floor. He had been beaten about the face and head, then stabbed in the chest and robbed. The reconstruction of bloodstains found on the interior front door and the adjacent wall documented that the victim was beaten about the face with a fist and struck on the back of the head with his cane. A three-dimensional dia- gram and photograph illustrating the evidential bloodstain pat- terns is shown in Figures 1(a) and 1(b).

A detail photograph of bloodstains next to the interior door is shown in Figure 2. Arrow 1 in Figure 2 points to the cast-off pattern directed left to right as blood was flung from the perpetrator’s fist while inflicting blows. Arrow 2 in Figure 2 points to three transfer impression patterns directed left to right as the perpetrator’s blood- stained hand contacted the wall and as the fist blows were being inflicted on the victim. Arrow 3 in Figure 2 points to blood flow from the victim’s wounds as he slumped against the wall.

Figure 3 contains a series of laboratory test patterns cre- ated to evaluate the patterns contained within Figure 2.c

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FIGURE 1a A three- dimensional diagram illustrat- ing bloodstain patterns that were located, docu- mented, and reconstructed.

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FIGURE 2 Positions of impact spatter from blows that were inflicted on the victim’s face.

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A crime-scene photograph of bloodstained areas.

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(a) (b)

The Institute of Applied Forensic Technology, Ocoee, Florida

(c)

The Institute of Applied Forensic Technology, Ocoee, Florida

(d)

The Institute of Applied Forensic Technology, Ocoee, Florida

(b) Patterns E and F The Institute of Applied Forensic Technology, Ocoee, Florida

(a) Patterns A, B, C

Figure 4 shows how the origin of individual impact spatter patterns located on the wall and door and emanating from the bleeding victim can be documented by the determination of separate areas of convergence.

A suspect was apprehended three days later, and he was found to have an acute fracture of the right hand. When he was

confronted with the bloodstain evidence, the suspect admitted striking the victim, first with his fist, then with a cane, and fi- nally stabbing him with a kitchen knife. The suspect pleaded guilty to three first-degree felonies.

FIGURE 3 (a) A laboratory test pattern showing an impact spatter. The size and shape of the stains dem- onstrate a forceful impact 90 degrees to the target. (b) A laboratory test pattern illustrating a cast-off pattern directed left to right from an overhead swing. (c) A labora- tory test pattern showing a repetitive transfer impression pattern produced by a bloodstained hand moving left to right across the target. (d) A laboratory test pattern illustrating vertical flow pat- terns. The left pat- tern represents a stationary source; the right pattern was produced by left-to- right motion.

The Institute of Applied Forensic Technology, Ocoee, Florida

FIGURE 4 (a) A convergence of impact spatter pat- terns associated with beating with a fist. (b) The convergence of impact spatter associated with the victim falling to the floor while bleeding from the nose. (c) The convergence of impact spatter associated with the victim while face down at the door, being struck with a cane.

The Institute of Applied Forensic Technology, Ocoee, Florida

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Physical evidence left behind at a crime scene, properly han- dled and preserved, plays a crucial role in reconstructing the events that took place surrounding the crime. Crime-scene re- construction relies on the combined efforts of medical exam- iners, criminalists, and law enforcement personnel to recover physical evidence and to sort out the events surrounding the occurrence of a crime.

The location, distribution, and appearance of bloodstains and spatters may be useful for interpreting and reconstruct- ing the events that produced the bleeding. An investigator or bloodstain pattern analyst can decipher from individual bloodstains the directionality and angle of impact of the blood when it impacted the surface of deposition. In addition, blood- stain patterns, consisting of many individual bloodstains, may convey to the analyst the location of victims or suspects, the movement of bleeding individuals, and the number of blows delivered.

Surface texture and an individual stain’s shape, size, and location must be considered when determining the direction and angle of impact of the bloodstain. Surface texture can greatly affect the shape of a bloodstain. The directionality of an individual bloodstain may be shown by the stain’s tail or the accumulation of blood because the tail or accumulation appears on the side opposite the force. The angle of impact of a bloodstain can be approximated by the shape of the blood- stain, or it can be more effectively estimated using the width- to-length ratio of the stain.

An impact spatter pattern occurs when an object impacts a source of blood, producing forward spatter projected forward from the source and back spatter projected backward from the source. Patterns created by impact spatter can be classified as low-velocity (>4 mm drops), medium-velocity (1–4 mm drops), or high-velocity (<1 mm drops). These classifications are for descriptive purposes only and should not be used to determine the kind of force that produced the pattern. The area of convergence of an impact spatter pattern is the area the in- dividual stains emanated from on a two-dimensional plane. The area of origin of a bloodstain pattern in three-dimensional

space may represent the position of the victim or suspect when the stain-producing event took place.

Gunshot spatter consists of very fine spatter originating from both forward spatter from an exit wound and back spat- ter from an entrance wound, or only back spatter if the bullet did not exit the body. Blood cast off from an object, typically a weapon or fist between delivering blows to a victim, may form an arc pattern on a nearby surface. The features of the pattern can suggest the kind of object that created it and the minimum number of blows delivered by the object. The char- acteristic spurts present in an arterial spray spatter are created by the continuing pumping of blood from an arterial injury. Expirated blood expelled from the mouth or nose may at first appear to be fine high-velocity or large low-velocity impact spatter. It may feature bubbles of oxygen in the drying drops or possibly be mixed with saliva. A void, where an object (or person) blocks the deposition of blood spatter onto a target surface or object, may give a clue as to the size and shape of the missing object or person.

Transfer patterns, created when an object with blood on it makes simple contact with a surface, may reveal the shape or texture characteristics of the object. Because the direc- tion of flows originating from either a single drop or a large amount of blood is caused by gravity, the direction of a pat- tern may suggest the original position of the surface when the flow was formed. A drip trail pattern shows a path of drops separate from other patterns; it is formed by single blood drops dripping off an object or injury. The presence of skel- etonization of the perimeter of a bloodstain suggests that the stain was disturbed after the edges had had sufficient time to skeletonize.

The precise appearance and location of each bloodstain at a crime scene is important. Therefore, each bloodstain pat- tern located at a crime scene must be properly documented in notes, photographs, and sketches. Medium-range and close-up photographs should be recorded using either the grid method or the perimeter ruler method to show the orientation and rela- tive size of the pattern and individual stains.

chapter summary

review questions

3. Violent contact between individuals at a crime scene fre- quently produces bleeding and results in the formation of ___________.

4. The proper interpretation of bloodstain patterns neces- sitates carefully planned ___________ using surface materials comparable to those found at the crime scene.

1. ___________ is the method used to support a likely se- quence of events at a crime scene by the observation and evaluation of physical evidence and statements made by individuals involved with the incident.

2. Reconstructing the circumstances of a crime scene is a team effort that may include the help of law enforcement personnel, medical examiners, and ___________.

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CRIME-SCENE RECONSTRUCTION: BLOODSTAIN PATTERN ANALYSIS 95

5. Bloodstain patterns may convey to the analyst the loca- tion and movements of ___________ or ___________ during the commission of a crime.

6. True or False: Harder and less porous surfaces result in less spatter, whereas rough surfaces result in stains with more spatter and serrated edges. ___________

7. Generally, bloodstain diameter (increases, decreases) with height. ___________

8. The ___________ and ___________ of blood striking an object may be discerned by the stain’s shape.

9. A drop of blood that strikes a surface at an angle of impact of approximately 90 degrees will be close to (el- liptical, circular) in shape. ___________

10. The angle of impact of an individual bloodstain can be estimated using the ratio of ___________ divided by ___________.

11. ___________ is the most common type of blood spatter found at a crime scene and is produced when an object forcefully contacts a source of blood.

12. True or False: Forward spatter consists of the blood projected backward from the source, and back spat- ter is projected outward and away from the source. ___________

13. The classification system of impact spatter is based on the size of drops resulting from the velocity of the blood drops produced, and patterns can be classified as ___________, ___________, or ___________ impact spatter.

14. True or False: The velocity classification system is a good way to classify impact patterns and to determine the kind of force that produced them. ___________

15. The ___________ is the point on a two-dimensional plane from which the drops originated.

16. The ___________ of a bloodstain pattern in a three- dimensional space illustrates the position of the victim or suspect when the stain-producing event took place.

17. The ___________ method is used at the crime scene to determine the area of origin.

18. A(n) ___________ is created by contact between a bloody object and a surface.

19. Movement of a bloody object across a surface, (light- ens, darkens) as the pattern moves away from the point of contact. ___________

20. True or False: Footwear transfer patterns created by an individual who was running typically show imprints with more space between them compared to those of an individual who was walking. ___________

21. True or False: The direction of a flow pattern may show movements of objects or bodies while the flow was still in progress or after the blood had dried. ___________

22. The approximate drying time of a(n) ___________ of blood determined by experimentation is related to the environmental condition of the scene and may suggest how much time has elapsed since its deposition.

23. The edges of a bloodstain generally ___________ within 50 seconds of deposition and are left intact even if the central area of a bloodstain is altered by a wiping motion.

24. A(n) ___________ pattern commonly originates from repeated strikes from weapons or fists and is charac- terized by an arc pattern of separate drops showing directionality.

25. True or False: Characteristics of a cast-off pattern arc cannot give clues as to the kind of object that was used to produce the pattern. ___________

26. When an injury is suffered to an artery, the pressure of the continuing pumping of blood projects blood out of the injured area in spurts creating a pattern known as ___________.

27. If a(n) ___________ pattern is found at a scene, it may show movement, lead to a discarded weapon, or pro- vide identification of the suspect by his or her own blood.

28. A bloodstain pattern created by ___________ features bubbles of oxygen in the drying drops and may be lighter in color when compared to impact spatter.

29. The shape and size of the blank space, or ___________, created when an object blocks the deposition of spatter onto a surface and is then removed may give a clue as to the size and shape of the missing object or person.

30. True or False: Each bloodstain pattern found at a crime scene should be noted, studied, and photographed. ___________

31. When documenting bloodstain patterns, the ___________ involves setting up a grid of squares of known dimen- sions over the entire pattern and taking overview, medium-range, and close-up photographs with and without the grid.

32. The ___________ method of bloodstain documentation involves setting up a border of rulers around the pattern and then placing a small ruler next to each stain to show relative position and size in photographs.

33. True or False: The pointed end of a bloodstain always faces toward its direction of travel. ___________

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96 CHAPTER 4

application and critical thinking

2. Investigator Priscilla Wright arrives at a murder scene and finds the body of a victim who suffered a gunshot wound, but she sees no blood spatter on the wall or floor behind it. What should she conclude from this observation?

3. Investigator Terry Martin arrives at an assault scene and finds a cast-off pattern consisting of tiny drops of blood in a very narrow linear arc pattern on a wall near the victim. What does this tell him about the weapon used in the crime?

1. After looking at the bloodstains in the figure, answer the following questions:

a. Which three drops struck the surface closest to a 90-degree angle? Explain your answer.

b. Which three drops struck the surface farthest from a 90-degree angle? Explain your answer.

c. In what direction were drops 2 and 7 traveling when they struck the surface? Explain your answer.

1. 2. 3. 4.

5. 6.

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Bevel, Tom, and Ross Gardner, Bloodstain Pattern Analysis: With an Introduction to Crime Scene Reconstruction, 3rd ed. Boca Raton, Fla.: CRC Press, 2008.

James, Stuart H., Paul E. Kish, and T. P. Sutton, Principles of Bloodstain Pattern Analysis: Theory and Practice. Boca Raton, Fla.: CRC Press, 2005.

Wonder, A. Y., Blood Dynamics. Burlington, Mass.: Elsevier Academic Press, 2001.

Wonder, A. Y., Bloodstain Pattern Evidence: Objective Approaches and Case Applications. Burlington, Mass.: Elsevier Academic Press, 2007.

further references

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Harold Shipman, Dr. Death

Kathleen Grundy’s sudden death in 1998 was shocking news to her daughter, Angela Woodruff. Mrs. Grundy, an 81-year-old widow, was believed to be in good health when her physician, Dr. Harold Shipman, visited her a few hours before her demise. Some hours later, when friends came to her home to check on her whereabouts, they found Mrs. Grundy lying on a sofa fully dressed and dead.

Dr. Shipman pronounced her dead and informed her daughter that an autopsy was not necessary. A few days later, Mrs. Woodruff was surprised to learn that a will had surfaced leaving all of Mrs. Grundy’s money to Dr. Shipman. The will was immediately recognized as a forgery and led to the exhumation of Mrs. Grundy’s body. A toxicological analysis of the remains revealed a lethal quantity of morphine.

In retrospect, there was good reason to suspect that Dr. Shipman was capable of foul play. In the 1970s, he was asked to leave a medical practice because of a drug abuse problem and charges that he obtained drugs by forgery and deception. However, Dr. Shipman

was quickly back to practicing medicine. By 1998, local undertakers became suspicious because

of the number of his patients who were dying. What is more, the patients who had died all were elderly women who were found sitting in a

chair or lying fully clothed on a bed. As police investigated, the horror of Dr. Shipman’s deeds became apparent. One clinical audit estimated that Dr. Shipman had killed at least 236 of his patients over a 24-year period. Most of the deaths were attributed to fatal doses of heroin or morphine. Toxicological analysis on seven exhumed bodies clearly showed significant quantities of morphine. Convicted of murder, Dr. Shipman hanged himself in his jail cell in 2004.

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