WK1 DISCUSSION QUESTION - CRIME SCENE RATIONALE

Physical Evidence and the Crime Scene

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OBJECTIVES

After reading this chapter you will be able to:

• Discuss the three roles or functions of physical evidence in the criminal investigation process and describe how physical evidence can serve as direct evidence or circumstantial evidence in criminal investigations.

• Identify the most important guidelines that should be followed in managing major crime scenes and collecting evidence from them.

• Explain the combined DNA Index System (CODIS) and how it increases the value of DNA analysis.

• Discuss the limitations of physical evidence.

• Discuss the evidentiary value of different types of physical evidence, especially biological evidence and DNA.

• Discuss the precautions necessary when collecting and handling biological evidence.

• Identify the specialty fields of forensic science.

From the CASE FILE The Murders of Nicole Brown Simpson and Ronald Goldman

Although the murders of Nicole Brown Simpson and Ron Goldman occurred in 1994, the crimes and the resulting investigation continue to capture the intrigue of the public. In 2016 two award-winning television shows aired that explored this case: The People v. o. J. Simpson: American Crime Story (FX Network/Netflix) and the documentary o. J. : Made in America (ESPN). Part of the attraction of th is story is related to the people involved-in particular, O. J. Simpson, a former NFL football star and Hollywood actor. This case is also unique and interesting from a criminal investigation perspective because of its many dimensions. It was and still is an excellent case study of the problems and difficulties of criminal investigations, and for that reason it is examined here. Another aspect of the investigation is also highlighted in Chapter 7.

The saga began on Sunday, June 12, 1994, just before 11 :00 p.m. Steven Schwab was walking his dog in the Brentwood section of northwest Los Angeles when he was confronted by an agitated Akita. As the dog followed Steven home, he noticed what appeared to be blood on its paws and belly. When Steven arrived home, the dog continued to behave in an unusual manner. Steven passed the dog along to his neighbor, Sukru Boztepe, who took the dog for a walk to see if he could find its owner. The dog took him to the front walkway of 875 south Bundy Drive. As Boztepe peered up the dark walkway, he saw what appeared to be a lifeless human body surrounded by a massive amount of blood.

At 12:13 a.m. the first police officers arrived at the scene. They found the body of a barefoot woman lying facedown with such severe wounds to her throat and neck area that she was nearly decapitated. Next to her was the body of a man. He was lying on his side and his clothes were also saturated with blood. The woman was identified by the police as the owner of the house, Nicole Brown Simpson, thirty-five, the ex­ wife of sportscaster and former pro football player O. J. Simpson. The body of the man next to her was first identified through the ID in his wallet, still in his back pants pocket, as Ronald Goldman, twenty-five, a waiter at a restaurant Nicole and her family had visited earlier in the evening. Police also discovered the two children of Nicole and Simpson, nine and six, asleep in their beds in the house.

By 2:10 a.m. Detective Supervisor Ron Phillips and detectives Mark Fuhrman and Brad Roberts had arrived at the scene. Shortly thereafter, detectives Tom Lange and Phil Vannatter from the Homicide Special Section of the Los Angeles Police Department (LAPD) Robbery Homicide Division were assigned as the lead investigators in the case; these detectives were on the scene by 4:30 a.m.

In examining the area in which the bodies lay, the detectives noticed several items: a set of keys (Goldman's), a beeper (Goldman's), a blood-splattered white envelope (containing the eyeglasses of Nicole's

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PHOTO 5.1: The crime scene of the murders of Nicole Brown Simpson and Ron Goldman revea led a great deal of evidence besides the most obvious: the bodies and blood. That evidence associated o. J Simpson to the crime scene and made him a suspect in the murders.

mother, who had left them at the restaurant earlier that night; presumably Goldman was at Nicole's house to return those glasses), a dark blue knit cap (believed to be the perpetrator's), and a blood-soaked left-hand leather glove (also believed to be the perpetrator's). Shoeprints transferred to the concrete surface from blood on the shoes led away from the bodies toward the back of the property. Alongside the shoeprint trail were drops of blood. The shoeprints and the blood drops were presumably from the killer.

Detectives decided to try to make contact with o. J. Simpson to notify him of the murder of his ex-wife and to arrange for him to get his children, who were still at the house. It was a five-minute drive from the south Bundy address to Simpson's estate on Rockingham Avenue. It was now about 5:00 a.m. Once at Simpson's property, detectives observed a white Ford Bronco with its front wheels up on the curb, the back of the vehicle sticking out into the street. The vehicle was registered to Simpson. on closer examination of the vehicle, Detective Fuhrman noticed what appeared to be blood on the vehicle near the driver's side door

CRIMIN AL INVESTIGATION

handle. Unable to summon anyone from the house, Fuhrman climbed the 5' stone wall that surrounded the property and let the other detectives in by unlatching the lock of the gate. The detectives knocked on the front door of the main house, but there was no answer, so they proceeded to the small guest houses located on the property. When they knocked on the door of the first house, a man by the name of Kato Kaelin, a houseguest of Simpson's, answered. At the next house they found Arnelle Simpson, Simpson's daughter. Fuhrman stayed with Kaelin while the other detectives accompanied Arnelle to the main house to confirm no one else was home or in any sort of danger. The detectives returned to Kaelin and interviewed him.

Kaelin told the detectives that before Simpson caught a late flight to Chicago that previous night, he went with him to a McDonald's and then returned home. Kaelin said that when they returned, Simpson went into the house and he, Kaelin, went to his bungalow. At about 10:45 p.m. Kaelin heard several loud banging noises outside near the bungalow's air-conditioning unit. He said he thought it was an earthquake. He went outside to investigate and saw a limousine parked at the gate to take Simpson to the airport. A few minutes later, according to Kaelin, Simpson rode off in the limousine. While Fuhrman checked the area around the air conditioning unit, Detective Phillips called Simpson at the Chicago hotel in which he was staying and notified him of the murder of his ex-wife. According to Phillips, Simpson never asked for any details about what happened, nor did he even ask which ex-wife had been killed (Simpson had two ex-wives). Simpson told Phillips that he would return to Los Angeles on the next available flight.

Shortly after this phone call, Detective Fuhrman returned to the house and told Vannatter of his discovery near the air-conditioning unit in the back of the bungalow occupied by Kaelin . According to Fuhrman, a bloodstained leather glove was lying on the ground there. (The defense later argued this glove was actually planted there by Fuhrman, a racist cop. Their claim was that both gloves were found at the crime scene and that Fuhrman took one of them with him to Simpson's.) It appeared to be the right­ hand match of the one found at the crime scene on Bundy. Then Vannatter discovered what appeared to be blood drops in the driveway that led to the Ford Bronco. Inside the Bronco he saw other red spots on the driver's side door and on the console between the two front seats. He discovered more blood leading to the front door of the main house. All this evidence

Chapter 5 • Physical Evidence and the Crime Scene

was later photographed, the glove was seized, the Bronco was impounded, and the entire area was secured. Detectives then obtained a warrant to search Simpson's house and vehicle.

With search warrant in hand, the detectives returned to the Rockingham property. While they were conducting their search of the premises, Simpson arrived home. Simpson and his attorneys agreed it would be okay for Simpson to talk with detectives Lange and Vannatter about the murders and to do so without his attorneys present. At 1 :35 p.m., June 13,

the interrogation of Simpson by Lange and Vannatter began (see Chapter 7). After the interrogation was over, Simpson was fingerprinted, wounds on his left hand were photographed, and a sample of his blood was drawn. The vial of blood was labeled and placed in an evidence envelope. Vannatter then took the sealed envelope back to Simpson's home and gave it to Dennis Fung, the criminalist who was responsible for collecting and recording the evidence at the Bundy and Rockingham scenes. To maintain the chain of custody, Fung checked the contents of the envelope

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and, according to procedure, wrote on the outside, "Received from Vannatter on 6-13-94 at 1720 hours." It was then placed in the LAPD's crime scene truck. This whole sequence of events was performed in full view of the numerous media film crews who were at the scene. At trial the defense argued that some of this blood was planted at the crime scenes. Interestingly, the nurse who drew the blood testified he drew eight cubic centimeters of blood, but the LAPD could only account for 6.5 cubic centimeters.

Meanwhile, back at Rockingham, the search of Simpson's residence revealed additional evidence of interest, including black socks later determined to be stained with blood and additional blood drops inside the house (more planted evidence, according to the defense). In all, forty-one items of evidence were collected from Simpson's Bronco, his house, and the Bundy crime scene. Through scientific analysis, numerous links were drawn from this evidence.1

Specifically, evidence recovered from the left-hand glove found at the Bundy crime scene consisted of the following:

PHOTO 5.2: Perhaps no evidence in the investigation (and trial) of O. J. Simpson was as important and as contested as the glove found on Simpson's property. Beliefs differ over whether the glove was dropped there by Simpson or placed there by detectives.

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• One hair from Nicole

• Fibers consistent with Goldman's shirt

• Fibers consistent with Goldman's jeans

• Dog hair from the Akita

By itself, this single glove was not that useful. one would suppose from the discovery of the glove that the murderer wore gloves while committing the homicides. However, potentially much more valuable was the matching right-hand glove found at Simpson's Rockingham estate. This glove connected Simpson (Simpson's property) to the crime scene. But there was more. On this glove were found the following:

• several hairs from Nicole

• Several pulled hairs from Goldman

• Fibers consistent with Goldman's shirt

• Dog hair from the Akita

• One fiber from the Bronco's carpet

• several blue-black cotton fibers consistent with fibers found on Goldman's shirt

Given the blood and fibers found on the glove, the fact it was found on Simpson's property, and the fact the identical matching glove was found at the crime scene, the right-hand glove seemed to link all the key individuals and places together: Simpson, Nicole, Goldman, and the crime scene. As such, this glove was an extremely valuable piece of evidence.

The following were present on the socks found in Simpson's bedroom at Rockingham:

• Blue-black cotton fibers

• Blood from Simpson and Nicole

If the socks were Simpson's and if the blood was not planted on them, then the socks served as corroborative evidence that at the very least Simpson was bleeding and near Nicole when she was bleeding.

Found on Goldman's shirt were the following items:

• One hair consistent with Simpson's

• Twenty-five hairs from Nicole

• several hairs from the Akita

CRIMIN AL INVESTIG ATION

• Four torn fibers from Nicole's dress

• several fibers from the knit cap

• one fiber consistent with the lining of both gloves

• Many blue-black fibers

This evidence associated Goldman with Simpson, Nicole, the gloves and cap of the perpetrator, and probably the clothes of the perpetrator (the blue-black fibers).

on Ron Goldman's pants were the following:

• Several hairs consistent with Nicole's

• several hairs from the Akita

This hair linked Nicole with Goldman and Goldman with the dog. This was relatively insignificant evidence in establishing who was responsible for the homicides but was perhaps useful for other purposes, such as for reconstructing the crime.

on the blue knit cap found at the Bundy crime scene were the following items:

• several hairs from the Akita

• Twelve hairs matching Simpson's

• several fibers consistent with Goldman's shirt

• One fiber consistent with the lining of both gloves

• one fiber consistent with the Bronco's carpet

Once again, this evidence provided additional strength to the conclusion Simpson was at the crime scene and was wearing the cap, at least temporarily. one might infer from this evidence alone that Simpson was the likely perpetrator. But there was even more physical evidence.

The blood evidence found at the Bundy crime scene included the following:

• Blood drops near the victims that matched Simpson's

• Four blood drops on the walkway that matched Simpson's

• Two shoeprints of size twelve Bruno Magli shoes in Nicole's blood

• Bloody prints from Goldman's boot that matched Goldman's and Nicole's blood

Chapter 5 • Physical Evidence and the Cr ime Scene

Through DNA analysis, the blood drops were confirmed to be Simpson's. This evidence linked Simpson to the scene of the crime (plus Simpson had unexplained injuries to his hand). In order for Goldman's boot to leave a print in Nicole's blood, she had to be bleeding before Goldman fell. It is reasonable to conclude that Nicole was attacked first, then Goldman. The shoeprints were probably left by the perpetrator.

The blood evidence found in and on the Bronco included the following:

• Blood that matched Simpson's found on the driver's door interior and on the instrument panel

• Blood on the center console that matched Simpson's

• Blood on the steering wheel that matched Simpson's and Nicole's

• Blood on the driver's side wall that matched Simpson's

• Blood on the carpet that matched Nicole's

• Blood on the center console that matched Simpson's, Nicole's, and Goldman's

More evidence linked Simpson with the victims and the crime scene. The blood evidence at Rockingham included the following:

• Two blood drops on a sock that matched Nicole's and two that matched Simpson's

• Blood drops in the foyer that matched Simpson's

• A blood trail on the driveway that matched Simpson's

on Friday June 17, 1994, Simpson was arrested for the murders of Nicole Brown Simpson and Ronald Goldman. The jury trial began on January 23, 1995. It ended with a "not guilty" verdict on October 2, 1995. The jury deliberated for less than five hours. Although there was a great deal of evidence that would lead one to the conclusion that Simpson killed his ex-wife and Goldman, it was explained away by the defense arguing that Simpson was framed .

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PHOTO 5.3: Detective Mark Fuhrman pointing to the glove near the body of Nicole Brown Simpson. Also notice the shoe prints in blood.

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case Considerations and Points for Discussion

1. A substantial amount of physical evidence appeared to associate o. J. Simpson with the murders of Nicole Brown Simpson and Ronald Goldman. What do you think was the single strongest piece of physical evidence that suggested Simpson committed the murders? Why?

2. According to o. J. Simpson's defense attorneys, the physical evidence that incriminated Simpson was planted or fabricated by the police. At the least, detectives made several critical mistakes in conducting the crime scene investigation and collecting evidence. Identify and discuss these mistakes.

3. Every investigation is a learning experience. What do you think should be the three most important lessons learned by the police as a result of this investigation?

4. Also: For additional insight into other possible explanations for the crime, more details about mistakes and oversights made by detectives, and speculation about other suspects, watch the YouTube video "BBC-OJ Simpson the Untold Story" (warning: graphic photos and descriptions are contained in the video). After watching the video, which alternative explanation for the crimes do you think is most persuasive?

• • • The Role of Physical Evidence in Criminal Investigations Physical evidence, also known as forensic evidence or real evidence, can serve several important roles in criminal investigations. First, physical evidence can help establish that a crime occurred (corpus delicti evidence) . For example, a dead body (along with the associ­ ated findings of an autopsy) may establish that a homicide occurred. Pry or toolmarks on a window can help establish that a burglary occurred. Semen recovered from a victim can help establish that a rape occurred. Of course, the lack of a dead body, an absence of pry marks, or the lack of semen does not necessarily indicate that a crime did not occur. A homicide can occur without the discovery of a dead body, a burglary can occur without evidence of forced entry, and a rape can occur without semen being present (or a rape may not have occurred even if semen is present). It is in this manner that physical evidence can help establish the elements of a crime or assist investigators in determining whether a crime actually occurred.

A second important role of physical evidence in criminal investigations is that it can be used to make associations between crime scenes, offenders, victims, and instruments (e.g., tools). In fact, forensic evidence collected during criminal investigations is used most often to establish associations. Consider the case of Simpson: The glove found on Simpson's prop­ erty that contained Nicole's hair and Goldman's hair and blood at the least associated Simpson's property with the homicide scene. Simpson's blood found at the crime scene and at his house further strengthened the association between Simpson and the homicides.

Additionally, in helping to establish the elements of a crime or in making associations between offenders, victims, and so forth, physical evidence can function as corroborative evidence and thereby support other evidence that establishes an issue in question. For example, physical evidence such as pry marks can support a victim's statement about a burglary having occurred, or DNA evidence such as semen can support a victim's identifi­ cation of the assailant.

Physical evidence:

Finally, certain forms of physical evidence may serve an identification function. For exam­ ple, as will be discussed in more detail later in this chapter, dental evidence (x-rays) can be used to determine the identity of an individual (usually a dead body), as can DNA evidence and fingerprints.

Evidence that can be seen and held that is created as the direct result of a crime; also known as real evidence.

It is also worthwhile to note that physical evidence can act as direct or circumstantial evi­ dence. In the Simpson case, for example, Simpson's blood drops at the crime scene were

Chapter 5 • Physical Evidence and the Crime Scene

direct evidence that he was at the crime scene. The fact that Simpson's blood was found at the crime scene was also used to infer that Simpson committed the murders.

Although physical evidence can help establish the elements of a crime; can make associa­ tions between offenders, victims, crime scenes, and so forth; and can serve a corroborative function with other evidence, physical evidence is not especially effective at initially identi­ fying a culprit when one is not already known. Of course, certain forms of physical evi­ dence (e.g., DNA) can lead to a culprit being identified or the crime being solved, but in the grand scheme of things this is a relatively uncommon occurrence. Consider once again the Simpson case. If Simpson had not been identified as a suspect through other means (e.g., first by being the ex-spouse of Nicole, then by having a sketchy alibi and an injured hand for which he had no clear explanation), the blood found at the crime scene that did not belong to either of the victims might not have been very useful in the investigation. It was only after Simpson was identified as a suspect through other means that the blood at the crime scene could then be compared and positively linked to Simpson via DNA analysis.

Consider the role of physical evidence in the following rather typical homicide cases:

• Relatives found an elderly man dead in the basement of his house with his skull crushed by a barbell that was still resting on his head. The victim's daughter told the police that a woman by the name of Jan, who was a drunken, violent prostitute, often lived with the victim. She said that her father and Jan often visited a neighborhood tavern. Investigators went to the tavern, asked about Jan, and obtained Jan's last name and an address where she was known to sometimes sleep. In looking for Jan, they first found Jan's sister. She told police that Jan confessed to her that she had killed the old man because he was going to kick her out of his house. She then told the police where Jan could be found. The police found Jan and told her that her sister said Jan had confessed to her. Jan then confessed to the police that she killed the old man. She was arrested and charged with the homicide.

• An individual was arrested as a suspicious person in Chicago. He was discovered driving a vehicle he did not own; the vehicle was registered to a person with a Detroit address.

Chicago police contacted the Detroit police about their discovery. Detroit police officers went to the address listed for the owner of the vehicle and found it locked. The police broke into the house and discovered a dead body. Using a driver's license in the dead victim's pocket, police identified him as the owner of the house and the vehicle. He had been stabbed to death. Chicago police were notified of the homicide. Upon checking the vehicle further, the police found many other items belonging to the victim. Upon questioning of the suspect, he confessed to the murder and theft. He was arrested and charged with murder.

• A brother and sister, both adults, were arguing about the brother moving out of the sister's house. A physical altercation resulted, and the sister was stabbed once in the leg. The police were notified of the argument by a neighbor. The police arrived and the victim stated in a dying declaration that her brother had stabbed her. He was still at the scene. When questioned, the brother confessed to killing his sister. He was arrested and charged with the crime.

Physical evidence did not play a role in the identification of any of these perpetrators. Why? In homicides, assaults, and even some rapes and robberies, often other evidence, such as eyewitnesses and circumstances (e.g., a relationship between the victim and the offender), leads to the identity of the perpetrator. Such evidence may be much more useful to investi­ gators in first identifying a perpetrator than any available physical evidence. Indeed, forensic evidence has the greatest impact in investigations when the chances of solving the crime are the smallest-that is, when a suspect is neither named nor identified quickly after the crime.

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Crime scene: The place that the crime occurred or where evidence may be located.

CRIMINAL INVESTIGATION

Having said this, it is also important to understand that physical evidence continues to become more and more important and influential in the criminal investigation process. This is especially true with DNA analysis, which has been of tremendous value in some criminal investigations and still has much potential yet to be realized.

• • • The Crime Scene and Its Management Physical evidence often begins its role in criminal investigations with its discovery and collection at the crime scene. A crime scene is the area within the immediate vicinity of where the crime occurred or was believed to have occurred, or where other evidence may be located. For example, in a homicide several places may be related to the crime and may contain evidence associated with the crime: the place where the victim was encountered, the place where the victim was first attacked, the place where the murder occurred, the place where the body was discovered, and the place where the murder weapon was dis­ posed of. Sometimes investigators make a distinction between primary and secondary crime scenes. In the Simpson case, the house of Nicole Brown Simpson was the primary crime scene; 0.]. Simpson's house was a secondary crime scene. Because secondary incor­ rectly suggests a less important scene and/or evidence, it is essential to understand that crimes may have multiple scenes, each potentially containing critical evidence. 2 Crime scenes commonly include residences, businesses, streets, yards, parking lots, vehicles, and hospitals. Regardless of its location and how it may be classified, a crime scene needs to be managed and controlled in order to preserve evidence and to ensure its integrity. Indeed, because critical evidence may be found at crime scenes, critical errors in the investigation may also occur there.3

Not all crime scenes are equal in their value to investigators. Some crime scenes may be more valuable than others because only certain people have access to particular places. Some crime scenes contain little evidence, whereas some contain a wealth of it. Accordingly, appropriate and necessary crime scene procedures vary considerably from crime to crime. In addition, resources and the policies of particular police departments may also dictate the proper course of action in crime scene investigations. Searching for and collecting physical evidence from crime scenes is not an inexpensive endeavor; it takes time and money. As a result, although relatively little time may be spent processing burglary crime scenes, much time may be spent on homicide scenes.

The basic guidelines discussed here are ones that should typically be followed by investiga­ tive personnel in preserving and recovering physical evidence in major crime investigations, such as homicides. 4

ARRIVING AT THE SCENE: INITIAL RESPONSE/PRIORITIZATION OF EFFORTS

When arriving at a crime scene, the initial responding officer should be thinking about protecting the scene as well as the safety of himself or herself, other officers, and citizens. The officer should approach the crime scene cautiously and be aware of any persons or vehicles in the area or leaving the area that may be related to the crime. The officer should make sure that it is safe to enter the crime scene to take further action. It is important that the officer remain alert and attentive when approaching and processing the scene.

Second, a determination has to be made about the legality of entering and searching the crime scene. Recall from Chapter 4 that there is not a crime scene exception to the search warrant requirement. A search requires a warrant or must be justified by an exception to the search warrant requirement (e.g., consent, plain view, exigent circumstances). If an exception does not apply, a search warrant must be obtained.

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Chapter 5 • Physical Evidence and the Crime Scene

Third, officers should be constantly mindful of possible threats to their safety, including hazardous materials, chemical threats, and dangerous persons. If such threats are apparent, appropriate personnel/backup should be immediately notified.

Fourth, after neutralizing dangerous persons or other threats, the officers' next responsibil­ ity is to provide or summon necessary medical attention for injured parties. Officers should ensure that medical personnel have guided access to the scene but do not unnecessarily disturb it. If resources allow or if the victim is in grave danger of dying, an officer should accompany the victim to the medical facility to document any comments made (e.g., a dying declaration) and to preserve evidence.

Fifth, the crime scene must continuously be protected from persons at or near the scene. Only authorized personnel and individuals essential to the investigation should be allowed to enter the scene. Some crime scenes are emotional places where relatives of the victim may understandably have little regard for the integrity and security of the crime scene. Bystanders, concerned citizens, and media representatives must also be prevented from affecting the crime scene. In addition, suspects and witnesses must be identified and sepa­ rated. Information may be compromised when witnesses are allowed to share with each other their versions of events prior to being interviewed.

Sixth, officers must establish the boundaries of the crime scene in order to protect it. Effective barriers can be established with crime scene tape and/or barricades. The boundaries should encompass where the crime actually occurred, paths of entry and exit of the suspects, and places where the victim/evidence may have been moved or discarded. The perimeter should be as large as possible. A crime scene sign-in sheet can be a useful tool to document the presence of authorized personnel at the scene. This sheet should be started as soon as prac­ tical after the boundaries of the scene have been established. No unauthorized persons, including citizens or media, should be allowed to enter or alter the crime scene. Persons who are at a crime scene when boundaries are established should be removed from the scene.

Seventh, whenever appropriate the initial responding officers should brief the investigators taking charge of the investigation. Witnesses and what they have said should be reported,

PHOTO 5.4: It is critical that crime scene boundaries be established and enforced. This ensures that the physical evidence contained at the scene is protected.

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Neighborhood canvass: A neighborhood canvass involves the door-to­ door questioning of residents who live in proximity to the crime scene.

CRIMINAL INVESTIGATION

physical evidence should be noted, and progress on other investigative activities should be reported. These actions provide critical continuity during the initial phases of the investiga­ tion. Communication regarding activities, responsibilities and duties, and evidence is extremely important.

Finally, all activities and observations of the responding officers should be recorded in the required reports as soon as possible. This documentation must include descriptive informa­ tion about the crime and the crime scene and information obtained from witnesses, victims, suspects, and other individuals at the scene.

PRELIMINARY DOCUMENTATION AND EVALUATION OF THE SCENE

With investigators now in charge of the crime scene, it is their responsibility to review the activities of the initial responding officers. The first step then is once again to assess the crime scene. Safety should be reevaluated, and crime scene boundaries should be confirmed. Investigators should make sure that suspects, witnesses, and victims continue to be sepa­ rated and monitored. Personnel should be assigned to interview these individuals as soon as is practical. A determination should be made about the necessity of obtaining a search warrant or obtaining consent to search. A path of entry and movement for authorized per­ sonnel should be established. The need for additional investigative resources (e.g., equip­ ment, legal consultation) should be determined and requested if necessary. Protection of the scene remains a critical responsibility of all investigators and officers at the crime scene.

In addition to these activities, it is also important to search for and locate other witnesses who may not have been present at the immediate crime scene. This is usually performed through a neighborhood canvass. A neighborhood canvass involves the door-to-door ques­ tioning of residents who live in proximity to the crime scene. Contact should be attempted at each and every address in the designated area. Whether contact is made with residents at each address should be recorded, along with who is (and was) present in the residence. The information provided by the resident(s) should also be recorded. Residents may have back­ ground about the place where the crime occurred or the people involved, they may have unknowingly seen or heard things that relate to the crime, or they may be the one who actually committed the crime. Because of this it is important to collect information about the activities of residents at the time the crime was believed to have occurred. Some resi­ dents may not come forward with information unless they are asked by an officer or inves­ tigator, so neighborhood canvasses can be valuable in developing information. It should be understood by the personnel who conduct the canvass that their role is to collect informa­ tion, not to give it. Some information about the crime will only be known by the perpetra­ tor, and the neighborhood canvass should not nullify this fact. In addition to questioning residents, vehicle license plate numbers or vehicle identification numbers of vehicles in the area should be recorded, and where those vehicles were parked should be noted. If infor­ mation arises in the investigation about vehicles that may have been involved in the inci­ dent, this information may be useful.

PROCESSING THE SCENE

The first step in processing the crime scene is determining who is responsible for what and establishing the composition of the investigative team. The responsibilities should be divided and the performance of activities supervised.

Next, the investigator in charge must require that all personnel follow procedures to ensure safety and the integrity of the evidence being documented and collected. Security of the evidence and the crime scene must be continually maintained.

The investigator in charge must also be responsible for or supervise the making of photo­ graphs, video, sketches, diagrams, measurements, and notes. Photographs, diagrams, and

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Chapter 5 • Physical Evidence and the Crime Scene

sketches are the primary means by which the crime scene is documented and serve as the official record of the condition and nature of the crime scene (see Exhibit 5.1 for an example of a crime scene sketch and diagram). Hand-drawn sketches are usually now used as a basis on which to develop a computer-assisted diagram. Photographs, diagrams, and sketches of the scene are evidence and must be documented and treated as such. Crime scene diagrams should be as detailed as possible and as close to scale as possible. Measurements of crime

EXHIBIT 5.1

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Locard's exchange principle: This principle holds that any time an individual comes into contact with a place or another person, something of that individual is left behind and something of that place or other person is taken with the individual.

CRIMINAL INVESTIGATION

scenes and the placement of evidence should be included. The diagram should include the following:

• Date, time, and location

• Weather and lighting conditions

• Identification and assignment of personnel

• Dimensions of rooms, furniture, doors, and windows

• Distances between objects, persons, bodies, entrances, and exits

• Measurements showing the location of evidence

• A key, legend, compass orientation, scale, scale disclaimer ("Dimensions are not to scale"), or some combination of these features5

With regard to crime scene photographs, each item should be photographed from close up and from long range before it is collected. Also, the conditions in which the photos were taken (e.g., weather, lighting) should be recorded, as should the direction, distance, and view of each pho­ tograph. Police departments often use a report form to log photographs. Crime scene photos should tell a story or should be able to be used to construct a story (see Case in Point 5.1).

In the next step in processing the scene, the investigator in charge should determine which items are to be collected and in what order. It is important to remember that any item present in the area may be evidence related to the crime, so the rule is "When in doubt, collect." Evidence that may be easily altered or destroyed should be collected first. If appropriate and necessary, other methods of evidence collection should be considered and used, including blood pattern documentation, blood illumination techniques, and/or projectile trajectory analysis.

Finally, the team members should ensure the proper collection, preservation, packaging, and transportation of evidence. Evidence must be collected and handled properly for it to be of use in an investigation and prosecution. The chain of custody is critical and must be maintained.

Various methods can be used when conducting a search for evidence at a crime scene. These methods include the grid, strip, and spiral search patterns (see Exhibit 5.2).

The basic idea for each of these approaches is to be thorough and systematic and not to overlook or miss any area or any item within the boundaries of the crime scene. The search should be approached with Locard's exchange principle in mind. This principle holds that any time an individual comes into contact with a place or another person, something of that individual is left behind and something of that place or other person is taken with the indi­ vidual. Although Locard's exchange principle is often valid, it is not always valid. Nevertheless, it is a useful approach to take when conducting a search. In essence, the guiding mindset should be "Expect to find evidence." Investigators must be careful that Locard's exchange principle does not apply to them. For example, when conducting a search, investigators should wear gloves to avoid leaving fingerprints, take other precau­ tions to avoid transferring evidence to a crime scene or between crime scenes, and avoid excessively handling evidence after recovery.

COMPLETING AND RECORDING THE CRIME SCENE INVESTIGATION

To complete the crime scene investigation, the investigator in charge should first establish a crime scene debriefing team. This team will discuss and determine the need for any remaining activities prior to releasing the scene and will discuss immediate steps that need to be taken during the follow-up investigation. Crime scene findings can be reviewed at this time, and a summary of the evidence collected can be offered. Second, a final survey of the crime scene should be made to make sure the crime scene investigation is complete and no materials or evidence have been left behind.

Finally, the investigator in charge should ensure that all necessary reports and other docu­ mentation are completed. This includes reports completed by the initial responding officers, emergency personnel documentation, entry/exit documentation, photographs/video, crime

- - - ---

Chapter 5 • Physical Evidence and the Crime Scene 101

CASE in POINT 5· 1 Crime Scene Photographs

Should Tell a Story

Photographs of crime scenes should be able to be used to

tell a story, as detailed in the following investigation.

An armed robbery occurred at a restaurant around mid­

night, just after closing time. Two suspects burst through

the rear door of the restaurant. One of the suspects grabbed

the manager and took him down the steps (Photo 5.5)

to the manager's office in the basement. The second suspect

grabbed another employee and followed down the steps.

once in the manager's office, one of the suspects demanded

the manager open the safe (Photo 5.6). The suspects then

filled their backpack with cash.

PHOTO 5.5

PHOTO 5.6

Unknown to the two suspects, another employee was

upstairs in the restaurant and heard the commotion. He real­

ized they were being robbed. He armed himself with a metal

trash-compacting rod (Photo 5.7), and as the robbers were

running up the steps toward the door to make their exit, he

hit one of them in the head with the rod. The robber was

knocked down some of the steps and dropped the backpack

full of cash (Photo 5.8). The blow to the head caused blood to

splatter onto a nearby wall and the cash to spill on the steps

(Photo 5.9 and Photo 5.10). The perpetrators scrambled to

gather some of the cash on the steps and fled through the

back door (Photo 5.11), leaving the backpack behind.

(Continued)

102 CRIMINAL INVESTIGATION

(Continued)

PHOTO 5.7

PHOTO 5.8

PHOTO 5.9

Chapter 5 • Physical Evidence and the Crime Scene 103

PHOTO 5.10

PHOTO 5.1 1

The police solved this crime due to an anonymous tip that

identified the two robbers. At the time the tip was received,

one of the perpetrators was already in jail on an unrelated

charge. His DNA profile was matched to the blood at the

scene. The other perpetrator was located and, upon interro­

gation, confessed to his role in the robbery. Both were found

guilty of armed robbery.

scene sketches and diagrams, and search warrant or other search documentation. This documentation can serve as a basis to direct further investigative activities and to provide continuity across investigators during the investigation.

An investigator usually only has one shot at a crime scene; therefore, the scene should be treated carefully and processed thoroughly. The value of critical evidence can be quickly destroyed through inappropriate or hasty crime scene procedures.

• • • Types of Physical Evidence Before discussing various types of physical evidence, a few words of clarification and cau­ tion about physical evidence are in order. First, it is important to understand that some

----------

104

Class characteristics: Features of physical evidence that allow it to be associated with a group of sources.

Individual characteristics: Features of physical evidence tl1at allow it to be associated with a particular source.

CR IMINAL INVESTIGATION

,,~~

Crime Scene Search Patterns

Spiral Strip Grid

forms of physical evidence have class characteristics, while other forms have individual characteristics. When evidence has class characteristics it can be associated with a group or class of sources. For instance, a paint chip could be associated with a particular make and model of an automobile but not a particular automobile. When evidence has individual characteristics it can be identified as originating from one particular source, such is the case when a DNA sample is determined to have come from a particular person.

A serious problem results when individual characteristic conclusions are drawn from evi­ dence that has, at best, class characteristic features. 6 Over the years a more precise under­ standing of individualization has developed. Strictly speaking, only biological evidence with DNA properties (nuclear DNA) can be accurately considered individualistic evidence. With other forms of physical evidence, especially bite marks, toolmarks, and writing samples, there is too little "science" associated with the interpretation and analysis of the evidence. According to the National Research Council, " [m]any forensic tests- such as those used to infer the source of toolmarks or bite marks-have never been exposed to stringent scientific scrutiny." 7 The council has also stated, "No forensic method other than nuclear DNA anal­ ysis has been rigorously shown to have the capacity to consistently and with a high degree of certainty support conclusions about 'individualization."' 8

A related problem with physical evidence can involve how the results of the tests on the evidence are interpreted and communicated. In particular, forensic examiners and other investigators sometimes use terms such as match (e.g., "The hair found in the trunk matched that of the victim"), identical, similar in all respects, or cannot be excluded as the source of. These can be persuasive conclusions, yet there is no consistent agreement as to the scientific meaning of these terms. What exactly is required to conclude that one piece of evidence "matches" another or that one piece of evidence is "identical" to another? These remain unresolved issues in most areas of forensic science. It is necessary to consider cautiously the conclusions that relate to many forensic tests.

With these issues in mind, the discussion offered here provides information on physical evidence, the potential usefulness of physical evidence in establishing proof, and basic guidelines for collecting and handling physical evidence.

Chapter 5 • Physical Evidence and the Crime Scene

• • • Biological Evidence Numerous types of biological evidence may be present and relevant in criminal investiga­ tions, including blood, semen, saliva, vaginal secretions, skins cells, hair, perspiration, urine, feces, and vomit. However, the most common types are blood, semen, saliva, and hair.9 As discussed, biological evidence may be especially useful in criminal investigations because it contains DNA. DNA (deoxyribonucleic acid) is the genetic building block of all living organ­ isms. It is found in virtually every cell in the human body, and its structure is the same in every cell. Except for identical twins, no two people have the same DNA. The DNA in a person's saliva is the same as the DNA in his or her hair, skin cells, and blood. Because of its absolute uniqueness and individual characteristics, human cells and the DNA contained in these cells can be a valuable form of evidence in criminal investigations. In addition, DNA can be easily and unknowingly be left by perpetrators at crime scenes and with vic­ tims (see Exhibit 5.3). Types of biological evidence are discussed here.

BLOOD

105

Blood is a common form of evidence found at scenes of serious crimes, such as homicides and assaults. Blood may be found in a variety of places: on or near the victim; at entrances and especially exits of crime scenes; in or on sinks, wash basins, and towels at the crime scene; on weapons found at the crime scene; and on the clothing of victims and perpetra­ tors, for example. Even if attempts have been made to remove blood, it can often still be located under vinyl flooring, under furniture, and in cracks and crevices.

DNA {deoxyribonucleic acid): DNA is the genetic building block of all living organisms and is unique to each individual, except identical twins.

When processing crime scenes and collecting evidence, investigators must "think DNA." DNA could be anywhere. Listed

below are a few possibilities.10

Evidence Possible Location of DNA Evidence Source of DNA

Bandana, hat, mask Anywhere (inside or outside) Dandruff, hair, saliva, sweat

Baseball bat or similar weapon End , handle Blood, hair, skin , sweat, tissue

Bite mark Clothing, skin Sal iva

Blanket, pillow, sheet Surface area Blood, hair, saliva, semen , sweat,

urine

Bottle, can, glass Mouthpiece, rim, sides Saliva, sweat

Cotton swab, facial tissue Surface area Blood, ear wax, mucus, tissue,

semen, sweat

Dirty laundry Anywhere Blood, semen, sweat

Envelope, stamp Licked area Saliva

Eyeglasses Ear or nose bridge, lens Hair, ski n, sweat

Fingernail, partial fingerna il Scrap ings Blood, sweat, tissue

Ligature, tape Inside/outside surface Blood, skin, sweat

"Through and through" bullet Outside surface Blood, t issue

Toothpick Tips Saliva

Used cigarette Cigarette butt Saliva

Used condom Inside/outside surface Recta l or vaginal cells, semen

Source: "DNA Evidence: What Law Enforcement Officers Should Know." 2003. National Institute of Justice Journal 249: 1-15.

106 CRIMINAL INVESTIGATION

PHOTO 5.12

PHOTO 5.13

PHOTO 5.14

Chapter 5 • Physical Evidence and the Crime Scene

PHOTOS 5.12-5.15: Blood is commonly encountered at scenes of violent crimes. It may or may not be obvious.

PHOTO 5.16: Blood on a suspect's hands may be informative in an investigation.

Blood consists of red and white blood cells, which are located in plasma-a nearly clear, watery liquid. An adult body contains about ten pints of blood. In liquid form blood is red, but when dry it can take on several different colors, including brown, black, gray, or even green, depending on the type and color of the surface on which the blood is located. Blood can be a valuable type of forensic evidence. Conventional serology can reveal the blood group and blood type of an individual (i.e., type 0, A, B, AB; presence or absence of the Rhesus factor antigen). Determination of secretor status may be useful in establishing a donor pool. Secretors are people whose blood group antigens are present in other body fluids. As a result, analysis of these fluids can reveal the person's blood group.

Most important, blood is an excellent source of DNA and, as such, is often subjected to DNA analysis (see the following discussion). The DNA in blood comes from the nuclei of

107

108 CRIMINAL INVESTIGATION

PHOTO 5.17: Blood being recovered from a bumper of an automobile as a result of a hit and run.

PHOTO 5.18: Attempts to clean up blood may not be successful.

white blood cells as a red blood cell does not have a nucleus. DNA analysis can produce virtually certain results that two blood samples have the same donor. Blood can also be useful for evidentiary purposes through an analysis of splatters, drips, and the location in which the blood was found.

Blood is often very visible to perpetrators and investigators and, as a result, perpetrators may take precautions to minimize the presence of blood by cleaning the crime scene or cleaning or disposing of articles stained with blood. Such precautions may not be effective, however.

Chapter 5 • Physical Evidence and the Crime Scene

Several methods are available to locate blood when it is not visible to the naked eye. An alternative light source (ALS) of 415 nanometers ("violet" light) may be used to reveal traces of blood not otherwise visible. In addition, the application of certain chemicals, such as a Luminol solution, to surfaces that at one time were contaminated with blood can reveal bloodstains via luminescence even if the blood is extremely diluted. Luminol reacts with iron contained in the blood, causing a visible blue glow. Chemicals, however, can destroy the properties of blood, so they are used primarily to detect the presence of blood that might otherwise go undetected. Other blood-illuminating chemicals, such as fluorescein, also react to other substances, such as certain cleaning products, so caution in interpretation is necessary.

Depending on the nature and condition of the blood evidence, various methods can be used to collect and package it. Blood in liquid form can be absorbed with a cotton cloth, air dried, and then packaged in a pa per bag. Plastic bags or containers should not be used. 11 Blood in liquid form should be refrigerated (but not frozen as tubes of liquid blood may break if frozen) prior to submission to the forensic laboratory. 12 For long-term storage, dried blood should be refrigerated or frozen. Blood splatters should be measured and photographed.

SEMEN Semen consists of sperm suspended in seminal fluid. One milliliter of semen from a healthy adult male contains approximately 60 to 100 million sperm cells. Semen also contains epithe­

lial cells (cells that cover internal body surfaces). In liquid form semen is grayish white and has a chlorine-type odor. When dry it is clear and starch-like. Seminal fluid is most often found as a result of sexual crimes, such as rape, and can be found with the victim, on the victim's cloth­ ing, on or in condoms, and in places where the assault may have taken place, such as on bed sheets or flooring. DNA analysis can be performed on sperm and/or epithelial cells.

Several tests can be performed to identify the presence of semen: the microscopic identifi­ cation of spermatozoa, the acid phosphatase test (which tests for the presence of the enzyme acid phosphatase found in seminal fluid), choline and p30 (which test for the presence of proteins in seminal fluid), and the use of ultraviolent (UV) light or an ALS. Semen and

PHOTO 5.19: If a condom was used in a sexual assault, its discovery could be valuable in the investigation.

109

Luminol: A chemical used to make blood otherwise invisible to the naked eye visible via luminescence.

Epithelial cells: Human tissue cells that cover internal body surfaces and can be used for DNA analysis.

110 CRIMINAL INVESTIGATION

CASE in POINT 5·3 An Improbable Discovery of Semen

In the 1980s and 1990s, a series of murders took place in

Washington State. The bodies of many women were found

in and near the Green River. Gary Ridgway was arrested on

charges related to prostitution, and eventually he became

a suspect in the killings. DNA was obtained from Ridgway,

and he was subsequently linked to four of the victims in the

most curious of ways. After raping and strangling some of his

victims, Ridgway put rocks in their vaginas and then put their

bodies in the Green River. The rocks preserved some of the

semen that was in the victims. The semen was recovered,

DNA was obtained from it, and it was compared and linked

to Ridgway. In addition, some of the clothing recovered from

the victims was found to have paint on it-the same type

of paint used by Ridgway in his job as a truck painter. Due

primarily to this evidence, and in order to avoid the death

penalty, Ridgway pied guilty to forty-eight murders, although

it is suspected he committed many more. He was sentenced

to life in prison without the possibility of parole.

spermatozoa are a rich source of DNA and are often the subject of DNA analysis proce­ dures. However, chemicals and UV light can affect DNA structure. 13

When collecting and packaging suspected liquid semen from crime scenes, it should be absorbed onto a clean cotton cloth or swab, air dried, and then packaged in a clean paper envelope with sealed corners. Semen-stained objects should be submitted to the laboratory in whole. Suspected semen should be absorbed from immovable objects onto a clean cotton cloth or swab moistened with distilled water. All semen evidence should be packaged in paper, not plastic. For long-term storage, dried semen should be refrigerated or frozen. 14

SALIVA

Although human saliva is mostly water, it also contains mucus, proteins, and enzymes as well as other substances, such as epithelial cells and white blood cells. DNA analysis is performed on the epithelial cells and white blood cells. In a criminal investigation, saliva may be most likely to be found on cigarette butts, bite marks, bottles, cans, chewing gum, clothing, and envelopes and stamps. Saliva is a good source of DNA and can be the subject of DNA analysis procedures (see Case in Point 5.4 and Case in Point 5.5).

Saliva can be easily overlooked as it is usually invisible to the naked eye, although it may become visible under an ALS. As with semen, there are chemical tests that can be used to identify it. In the case of saliva, such tests detect amylase, an enzyme found in high concen­ trations in saliva. However, the test is not definitive because other types of tissue and bodily fluid also contain amylase.

The collection and packaging of saliva is the same as with semen. In liquid form it should be collected via a clean cotton cloth or swab and air dried. If possible, entire saliva-stained objects should be collected. If it is not possible to collect the object that contains the saliva or to cut out the saliva sample, the saliva stain may be collected by using a cotton swab moistened with distilled water. A control sample of an area close to the saliva should also be collected using the same distilled water and type of swab used to collect the evidence. All items should be packaged in paper envelopes or bags, not plastic. The control sample should be packaged separately. Care must be taken that metal or glass items are not frozen. For long-term storage, dried saliva should be refrigerated or frozen.15

HAIR

Hair is most likely to be found in homicides and assaults, especially when some struggle between the victim and the perpetrator took place, and in hit-and-run cases that involve a person. Hair may also be found on the clothing of victims and perpetrators, in and on

Chapter 5 • Phys ica l Evide nce and the Crime Scene

In February 2017 Brian Golsby, twenty-nine, was arrested

for the murder, rape, and robbery of college student Reagan

Tokes, twenty-one. After abducting and robbing Tokes,

Golsby used her car to drive her to a park near Columbus,

Ohio, where he raped and murdered her. He was identified

111

as the perpetrator through DNA recovered from a cigarette

butt in Tokes's car. Golsby's DNA was on file as the result of

a previous robbery and attempted rape conviction. He had

just been released from prison three months prior to this

incident.16

PHOTO 5.20: Even careful perpetrators may not th ink before they discard a smoked cigarette at a crime scene. Of course, a cigarette butt found at a crime scene is not necessa ri ly one that was smoked by the perpet rator.

An eight-year-old girl was abducted, sexually assaulted, and

left for dead in a wooded area. Before leaving the victim,

the perpetrator bound her hands and arms with duct tape

and wrapped the tape around the girl's head, including her

mouth and nose, in an attempt to suffocate her. After the

perpetrator left, the girl was able to free her hands and

remove the tape from her mouth and nose. She then was

able to summon help from a passing motorist. Upon being

interviewed the girl provided investigators with a descrip­

tion of the attacker, and a composite sketch was developed

and quickly released to the media. The police obtained

information from several people that the person depicted

in the sketch looked like a man by the name of Robert

Leven (not his real name), who worked in a prison nearby.

Meanwhile, analysis was being performed on the evidence

recovered with the victim, the most significant of which

was the duct tape. Although there were no fingerprints on

the tape, investigators did find saliva. It was reasoned that

the perpetrator used his teeth to tear the tape and, in the

process, his saliva was transferred to the tape. The saliva

underwent DNA analysis and a DNA profile was produced.

The DNA on the duct tape matched that of Robert Leven.

Leven was arrested and convicted of sexual assault, among

other offenses.

112 CRIMINAL INVESTIGATION

vehicles, and on personal items, as well as in places such as the clothes dryer lint trap, wash­ ing machines, and sinks.

Hair consists of an outer core of overlapping cells known as the cuticle, the cortex (which con­ tains the pigment of the hair), and the medulla (an inner layer of cells). Hair also contains a root, which can be of great use in the scientific analysis of the hair. Significant variation in hair structure is often found within the same individual, particularly in hair from different places on the body (e.g., head, face, pubic area) . As a result of this, a range of samples must be analyzed when comparing the structure of the hair. Through the relatively simple microscopic examina­ tion of a hair shaft, it is possible to draw several conclusions about the hair: whether it is from a human or an animal (and if it is from an animal, what type of animal), the race of the indi­ vidual, the body area from which the hair came, the method of removal, color and shaft form (e.g., straight, curly), and whether the hair was damaged or altered (e.g., dyed or bleached). Chemical examination of the hair may reveal the presence of contaminants in the hair and may identify ingested drugs and how long ago those drugs were ingested. The most powerful of all is DNA analysis performed on the root of a hair. Even DNA analysis conducted on the shaft of the hair is likely to be more useful and discriminating than analyses conducted on the features of the hair. Non-DNA analysis of hair is generally unable to positively associate hair to a spe­ cific individual, but it may be useful in excluding certain persons as the source of the hair.17

OTHER BODILY FLUIDS AND SUBSTANCES

Although relatively uncommon at crime scenes, urine, feces, vomit, and perspiration can all be subjected to DNA analysis and therefore represent potentially valuable evidence in a criminal investigation. As with saliva, it is typically the epithelial tissue cells found in these substances that undergo DNA analysis. The methods used in the recovery and storage of these substances depends on the nature and location of the sample. Samples should be col­ lected with either a sterile eyedropper, cotton swab, or gauze pad and stored in a sterile test tube or other sterile container.18

Hair samples should be packaged in an envelope with sealed corners. Hair should be care­ fully collected with clean tweezers to prevent damage to the hair root. Hair that is mixed

PHOTO 5.21: A hair hangs from an overhead air duct in the basement of a house in which a murder occurred. Because potential evidence can be easily overlooked, the crime scene search must be focused on even the smallest details.

Chapter 5 • Physical Evidence and the Crime Scene

,Ji I ~I~- { t)4-\\)1:.S-'.> "><&< \.e<l.c( ltjlrt-

we',t()

PHOTO 5.22: Hair recovered from the headlight area of an automobile in a hit-and-run investigation.

with bodily fluid should be air dried prior to packaging in paper, not plastic. 19 In collecting comparison samples, at least twenty-five to fifty hairs from different parts of the head (or pubic area) should be obtained. Hairs should be combed and pulled out20 and collected by a trained medical professional.

FINGERNAIL SCRAPINGS, SKIN CELLS, AND TOUCH DNA

It is standard practice to protect and collect tissue from the fingernail scrapings of victims of violent crime. If contact occurred between the victim and the perpetrator in a violent interac­ tion, skin, blood, and/or hair may be recovered from under the fingernails of the victim. These substances can undergo DNA analysis and play a central role in an investigation (see Case in Point 5.6). Medical personnel (medical examiners in the case of homicides) are typically respon­ sible for collecting this evidence. When dealing with homicides, investigators should protect the hands of the victim with sterile paper bags until such time as the evidence can be collected.

The amount of biological sample necessary to conduct a DNA analysis has gotten smaller and smaller over time, to the point that today the substance need not even be visible. Such is the case with touch DNA. Touch DNA involves the recovery of DNA from very small samples of skin cells left on an object or surface as the result of simply touching it. Although touch DNA is a major development in the capabilities of DNA analysis, it is not without its drawbacks. First, since the skin cells cannot be seen, it takes an educated guess to find them. Second, with more sensitive DNA testing comes a greater potential for contamination during collection and analysis. Third, secondary transfers are more likely to be detected with touch DNA, and as a result, there may be an increased risk of false conclusions. For example, if Subject A shakes the hand of Subject B, and then Subject B holds a murder weapon, Subject Ns skins cells may be recovered from the murder weapon, thus potentially leading to the incorrect conclusion that Subject A is the killer. It must be realized that the inadvertent transfer of touch DNA is a real possibility and conclusions must therefore be carefully drawn.21

The collection of skin cells should be performed with a sterile, cotton-tipped applicator (swab) wetted but not saturated with one drop of sterile water from a sterile dispenser. The area where skins cells are suspected should be swabbed with the entire surface of the swab. The swab should then be air-dried and placed in a sterile paper enclosure. 22

113

Touch DNA: The DNA analysis of cells discarded simply as the result of touching an object.

114

DNA analysis: A procedure w hereby individuals are identified by examination of DNA in certain locations.

CRIMINAL INVESTIGATION

PHOTO 5.23: Standard procedure in cases where homicide is a possibility is to protect the hands of a victim with sterile paper bags Th is may preserve evidence transferred from the perpetrator

PHOTO 5.24: An investigator attempts to collect touch DNA from a vehicle's steering wheel.

DNA ANALYSIS AND ITS IMPACT ON THE USEFULNESS OF BIOLOGICAL EVIDENCE

The most significant scientific advance in the technology of criminal investigation ever is DNA. DNA analysis (or typing) was first used in a criminal investigation by Dr. Alec J. Jeffreys in 1987 to corroborate a suspect's confession that he was responsible for two rape/ murders in England. Tests proved that the suspect was not the perpetrator. Police then

·.

Chapter 5 • Phys ical Evidence and the Crime Scene 115

On August 2, 2016, thirty-year-old Karina Vetrano went for a

run at a park near her home in Queens, New York. She did

not return . Within a few hours, her body was found. She had

been beaten, sexually assaulted, and strangled to death.

Investigators recovered DNA, presumably from the killer,

under Karina's fingernails, on her neck, and from her cell

phone, which was next to her body. A matching DNA profile

was not found in the FBl's CODIS DNA data bank (see the

later discussion). Police considered several suspects based

on composite sketches and reports of suspicious persons

around the park, but none matched the DNA recovered from

the victim. Upon broadening their search for suspects, police

recalled receiving a report of a prowler in the neighborhood of

the park several months earlier. To leave no stone unturned,

police found and interviewed the prowler suspect, Chanel

Lewis, and requested a DNA sample (buccal swab) from him.

Sure enough, his DNA matched the DNA recovered from the

victim. Upon interrogation, Lewis confessed to the murder.23

obtained DNA samples from several thousand men who lived in the area in order to iden­ tify the true perpetrator. Although the perpetrator attempted to avoid providing a DNA sample, he was eventually identified and charged with the crimes. DNA printing was first used in the United States in a criminal case in 1987, during which a Florida jury convicted Tommy Lee Andrews of rape.24

DNA analysis may be used to associate positively and absolutely a perpetrator to a crime scene, to the victim, or to tools used in the crime. Similarly, DNA analysis can be used to eliminate positively and absolutely a person from consideration as a suspect. As such, it would be inaccurate to consider DNA analysis only a tool of the prosecution used to con­ vict suspects. DNA analysis is a powerful tool of justice-a tool that can be used to identify and convict the guilty and to free the innocent.

DNA can also be used to confirm the identity of victims or the remains of victims when a complete body is not found. In cases such as this, a DNA sample may be taken from hair recovered from the victim's hairbrush or from skin cells recovered from the victim's tooth­ brush or clothing and then compared with the remains. Another possibility is to compare the DNA from relatives with the DNA of the body or remains.

Extraordinary caution needs to be exercised when collecting DNA-analyzable evidence for at least two reasons: (1) the biological material may contain hazardous pathogens (e.g., human immunodeficiency virus, hepatitis) that can cause lethal diseases and (2) because samples containing DNA can be easily contaminated (see Exhibit 5.4). Contamination could happen if someone sneezes, coughs, or even talks over the evidence, or if someone simply touches the evidence without taking sterile precautions.

When transporting or storing evidence that may contain DNA, the evidence must be kept dry. The evidence should be stored in paper bags or envelopes. Evidence that may contain DNA should never be placed or otherwise stored in plastic bags because plastic will retain moisture that may damage the DNA. Direct sunlight and warmer conditions can also damage DNA evidence. Staples should not be used to secure evidence bags as an accidental injury from the staples might lead to contamination of the evidence. Of course, the chain of custody must also be maintained. The chain of custody would likely include the following individuals:

• The person who collected the particular piece of evidence and began the chain of custody

• The person who transported the evidence to the police department or crime lab

• The person who logged the evidence into the evidence room or the person who received the evidence at the lab

• The person who received the evidence from the lab for final inventory

116 CRIMINAL INVESTIGATION

';~

EXHre11 '5.4

Precautions When Collecting and Handling Biological Evidence25

Biological material may contain hazardous pathogens,

such as the hepatitis A virus, that can lead to potentially

lethal diseases. At the same time, such material can eas­

ily become contaminated. To protect both the integrity of

the evidence and the health and safety of law enforcement

personnel, officers should take the following precautions:

• Avoid touching any area where DNA might exist.

• Avoid touching one's own nose, mouth, and face when

collecting and packaging evidence.

• Air-dry evidence thoroughly before packaging.

• Put evidence into new paper bags or envelopes. • Wear gloves and change them often.

Investigators shou ld not place evidence in plastic bags

or use staples. • Use disposable instruments or clean them thoroughly

before and after handling each sample.

Buccal swab: To collect DNA from a subject, a buccal swab is most often performed; this involves collecting cells from the inside surfaces of the cheeks.

Mitochondrial DNA (MtDNA): A form of DNA inherited from one's biological mother only.

Nuclear DNA: A form of DNA unique to an individual.

The collection of comparison (or reference) DNA from a suspect most often involves the use of a buccal (oral) swab. A sterile cotton swab must be used for this purpose. The inside surfaces of the cheeks should be rubbed thoroughly with the swab. The swab should then be air dried and placed in a paper sleeve or an envelope with sealed corners. Swabs from different people should be packaged separately. The samples do not need to be refrigerated. Other, less desirable, but potential reference samples can be obtained from surgical samples, pulled teeth, an item of clothing worn only by the individual of interest, or a toothbrush used only by the person.26

THE SCIENCE OF DNA There are two types of DNA: mitochondrial DNA (MtDNA) and nuclear DNA. MtDNA is found in the mitochondrion in each cell of the body; nuclear DNA is found in the nucleus of a cell. MtDNA is more limited in function than nuclear DNA. MtDNA is inherited from one's biological mother only. It has limitations compared with nuclear DNA in that it can­ not differentiate between individuals who have the same maternal lineage (i.e., a brother and a sister, or a mother and a daughter, will have the same MtDNA). MtDNA is analyzed when only hair shafts, bone, or teeth are available or when other biological evidence is severely degraded. 27

Nuclear DNA consists of billions of pairs (base pairs) of adenine, cytosine, guanine, and thymine (commonly referred to as A, C, G, and T) structured in the form of a double helix. Very simply, think of the double helix as a twisted ladder and the base pairs as the rungs in the ladder. About 99.9 percent of the DNA base pairs of each human are the same, but certain areas of the DNA are unique, thus making DNA unique.28 Of particular importance is that the sequence (or order) of the base pairs repeats, and the pattern of repeats are distinct across individuals. As such, DNA typing consists of examining particular locations (loci) in the DNA and identifying the base pair sequence pattern. Sometimes reference is made to a thirteen- or twenty-loci DNA profile. In the past the FBI used thirteen specific short tandem repeat (STR) loci to serve as a standard DNA comparison, but as of January 1, 2017, twenty loci were being used. The chances that two people will have the same DNA profile can be as remote as one in one billion or less.

Chapter 5 • Physical Evidence and the Crime Scene

PHOTO 5.25: Elimination samples may need to be taken to eliminate from consideration those individuals who had legitimate reason to be at the crime scene or in contact with the victim. In addit ion, the victim's DNA should be compared to other DNA found at the crime scene.

The general procedure in conducting DNA analysis is as follows:

• Determine whether the substance is biological evidence and whether it is from a human or animal.

• Isolate the DNA from the biological evidence.

• Analyze the DNA and obtain a DNA print (pattern) from specific regions (loci) of the DNA.

• Compare the results of the DNA analysis performed on the biological evidence with a suspect (or sample of possible suspects) to determine if the suspect is the source of the DNA.

The most common method of analyzing nuclear DNA today is known as polymerase chain

reaction (PCR).29 With the PCR technique, the DNA is copied many times (amplified). Two DNA molecules are produced from the original molecule and are repeated many times until millions of copies of the DNA sequence are produced. From these copies a DNA profile can be generated. PCR can be used if a sample consists of a few cells or is degraded, but it is particularly susceptible to contamination. ·

On the basis of DNA testing, one of three conclusions may be drawn. First, the suspect may be included as the possible source of the evidence; however, the certainty of the inclusion will depend on the number of locations on the DNA strand that are examined and how common or rare the resulting DNA print is in the general population. Second, in the same manner that an individual can be included as a suspect, an individual can also be excluded as a suspect. Third, the results of the analysis may be inconclusive- a peRson cannot be included or excluded as the source of the evidence. Inconclusive results may occur for a variety of reasons: the poor quality of the DNA sample may not allow for interpretable results, the evidentiary sample may contain a mixture of DNA from several individuals, or the sample may have been contaminated.

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117

Polymerase chain reaction (PCR): The most commonly used technique of analyzing DNA today.

118

Combined DNA Index System (CODIS): A national database operated by the FBI that contains DNA profiles collected from various sources; it is used to identify DNA samples.

CRIMINAL INVESTIGATION

While the science of DNA analysis is difficult to attack, attempts have been made to get around it (see Case in Point 5. 7). More common is that the procedures used in collecting the biological evidence are called into question. All the science and precision of DNA anal­ ysis can be foiled if the evidence is collected incorrectly or if claims can be made about the overall integrity of the evidence. Even though the scientific basis of DNA analysis has been established, the Supreme Court has provided for extensive discovery requirements in the admission of the results of the analysis. In Schwartz v. State (1989), the court stated that

ideally, a defendant should be provided with the actual DNA sample(s) in order to reproduce the results. As a practical matter, this may not be possible because forensic samples are often so small that the entire sample is used in testing. Consequently, access to the data, methodology, and actual results is critical .. . for an independent expert review.

Further, the results of laboratory examinations must be accompanied by in-person testimony of the individual who examined the evidence (Melendez-Diaz v. Massachusetts, 2009); a substitute witness does not satisfy the requirement (Bullcoming v. New Mexico, 2011).

Until relatively recently DNA evidence was limited in the same manner that physical evi­ dence is limited; it was generally not useful in identifying a perpetrator when one was not already known. Only when a suspect was identified through some other means could the recovered DNA evidence be compared with the DNA taken from the identified suspect. However, technological advances and legal provisions have made DNA much more useful in investigations. For example, the Combined DNA Index System (CODIS) is an electronic system that allows federal, state, and local crime laboratories to exchange and share DNA profiles electronically.30 Today, all states participate in CODIS. As of December 2016, the National

CASE in POINT s.7 A Fool's Attempt to Fool DNA

Occasionally a suspect attempts to get around the science of

DNA. One such case was that of Anthony Turner, a convicted

and incarcerated serial rapist. While serving time in prison for

three rape convictions-convictions obtained in part through

DNA analysis of semen recovered from his victims-Turner

devised a plan to try to fool investigators and to make author­

ities question the validity of the DNA analysis results. The plan

unfolded with an apparent fourth sexual assault in the same

neighborhood where Turner had committed his rapes years

before. A woman contacted the police, told them she had

been raped, and underwent a sexual assault examination. The

recovered semen was analyzed, a DNA profile was created,

and that profile was compared with the DNA profiles in the

state's DNA bank, which contains DNA samples of all convicted

felons in the state. A match was made to Anthony Turner. on

hearing of this match, Turner argued that he obviously did not

commit this crime since he had an iron-clad alibi-he was in

prison at the time of the assault. He reasserted his claim that

he did not commit any of the other rapes either. Initially, this

was rather puzzling. Could two people-Anthony Turner and

the real rapist-have the same DNA profile? If Anthony Turner

had an identical twin, no one knew about it. As investigators

questioned Turner's associates in prison and the "victim" of

the latest rape, Turner's scheme unravelled. It was discovered

that about a month prior to the last "rape," Turner had told his

mother that she should expect an envelope in the mail from

him and that she should give this envelope to one of Turner's

female friends. Investigators then learned that in this envelope

was a ketchup packet containing Anthony's semen. Anthony

smuggled his semen out of prison! Anthony's female associ­

ate then used this semen to stage the rape. An ambitious and

imaginative plan, but one that did not work.

Other instances have also been reported of perpetrators

leaving DNA evidence such as hair, fingernails, and blood

from other sources at crime scenes in an attempt to mis­

direct the investigation. Investigative personnel should be

aware of this possibility when collecting such evidence.

Chapter 5 • Physical Evidence and the Crime Scene 119

DNA Index system (NDIS; the part of CODIS that actually holds the DNA profiles) con­ tained over 12 million offender profiles (DNA collected from offenders upon conviction for an offense), 2.5 million arrestee profiles (DNA from offenders upon arrest, as provided by some states), and 750,000 forensic profiles (DNA collected from crime scenes).31 CO DIS also contains DNA databases on missing persons, relatives of missing persons, and unidentified human remains. CODIS has assisted in more than 344,000 investigations.32 Each state has at least one CO DIS-participating lab; in total, 190 public labs have access to CO DIS.

In addition to CO DIS, states operate DNA banks that are usually linked to CO DIS but can be searched independent of COD IS. Some states require DNA from all convicted felons be entered into the system; some states collect DNA from anyone simply arrested for a felony or a violent felony. Some states collect DNA only from convicted sex offenders. Investigators can enter the DNA profiles obtained from crime scene evidence into these data banks and the system can scan the stored prints for a hit (See Case in Point 5.8). However, if the per­ petrator's print is not in the system, a match will not be obtained. In that case the culprit will still have to be identified through other, more traditional, means.

• • • Other Types of Physical Evidence FINGERPRINTS

The early foundation of forensic science rested on the principle that each person has a unique pattern on his or her fingers. This principle is still valid, and fingerprints are still

Sara Miller (not her real name) boarded a public bus for the

ride home from her waitressing job at a local restaurant.

She was never seen alive again. Her parents reported to the

police that she did not return home that evening, and, even

more alarming, they were receiving bizarre text messages

from Sara-or at least from someone using her cell phone.

Sara's boyfriend also received such messages. One read,

"We broke both her arms and legs and cut off her feet PS put

more minutes on the phone." Needless to say, everyone was

extremely concerned. As police were trying to determine the

whereabouts of Sara and her phone, her body was discov­

ered by workers at a recycling center in the city. She had

been strangled, beaten, stabbed, and sexually assaulted. Her

body had probably been dumped in a recycling bin and then

unknowingly transported to the recycling center.

Investigators conducted hundreds of interviews-with bus driv­

ers, family members, coworkers, friends, and associates-but

little progress was made in the investigation. Investigators

kept trying to track the location of the cell phone; whoever

had it was still using it to send text messages to people

listed in Sara's phone. Just as investigators were narrow­

ing in on the location of the phone, the phone went dead.

Presumably it had been destroyed. Meanwhile, the semen

recovered from the victim was analyzed for DNA, and the

resulting DNA profile was entered into the state's DNA bank.

There was a hit Steven Barthew (not his real name), age

twenty-two. Even better, Steven was currently being held in

the county jail. He had been arrested for a hit-and-run with

a car did not have permission to be driving. His DNA profile

was in the DNA bank due to a previous robbery conviction.

Investigators talked to Steven. Confronted with the DNA

evidence, he confessed to the murder but gave various ver­

sions of what happened. He told investigators that voices

told him to kill Sara. Steven's apartment was searched. one

item seized was a pair of boots confirmed through additional

DNA analysis to contain Sara's blood; the chance it was not

Sara's blood were one in eleven billion. Detectives also found

a note in Steven's apartment that read, "Never kill anyone

you know, Never have a motive, Never follow a discernible

pattern, Never carry a weapon after it has been used, Isolate

yourself from random discovery, Beware of leaving physical

evidence." It is likely that without the DNA analysis and data

bank, and the DNA hit, Steven would not have been appre­

hended quickly. Steven was convicted of homicide and sen­

tenced to life in prison without the possibility of parole.

120

Friction ridge analysis: A formal name for fingerprint analysis; it involves the examination of the ridge structures of fingers (or hands or feet) .

Latent prints: Fingerprints made when oi ls and perspiration on fingertips are transferred to a surface and made visible only through the use of various forensic techniques.

CRIMINAL INVESTIGATION

potentially valuable evidence in criminal investigations. Fingerprints consist of ridges, depressions (i.e., hills and valleys), and separations (where ridge lines end or split). Fingerprints remain unchanged and consistent throughout one's lifetime. Each fingerprint on each finger is unique. Fingerprints can be useful because perpetrators can leave them on items and at crime scenes.

Fingerprints can be broadly classified on the basis of the pattern of ridges that comprise the print. As illustrated in Exhibit 5.5, these patterns are classified as loops (ulnar loop, radial loop), whorls (plain whorls, double loops, central pocket loops, accidental loops), and arches (plain arch, tented arch). The most common type of fingerprint is the loops pattern (approximately 66 percent of the population have loop prints), followed by whorls (approx­ imately 33 percent). Only about one person in twenty has prints that resemble arches.

Fingerprints taken as a result of the fingerprinting process (i.e., "being fingerprinted") are usually recorded on a ten-print fingerprint card either through the use of ink or the digital capture of prints. On the card the prints are arranged as a double row in a particular sequence (see Exhibit 5.6).

The analysis of fingerprints (as well as sole and palm prints) is known as friction ridge anal­ ysis, and it consists of comparisons of the impressions left by the ridge structures of fingers (or hands or feet). Friction ridge analysis is a means by which individualization can be determined, although this is highly dependent on the quality of the print, among other factors. 33 There are three conclusions that may result from a comparison of fingerprints: individualization (or identification), exclusion, or inconclusive. An identification (or indi­ vidualization) is made when prints from two different sources could not have produced impressions with the same degree of agreement in ridge features. It is important to under­ stand that in contrast to DNA matches, this is a subjective assessment as there are no sta­ tistics by which to identify the probabilities of a match based on population distributions of certain friction ridge features. 34 Exclusion is made when prints show observable differ­ ences in ridges. An inconclusive conclusion is appropriately drawn when similarities and differences in prints are not able to be determined.

Fingerprints recovered from a crime scene generally fall into one of three categories: (1) visible transferred prints, such as when ink, blood, or some other visible liquid mate­ rial is transferred from the fingertip to another surface; (2) visible impression prints, which occur when the print is left in a soft or sticky material, such as wet paint, clay, or putty; and (3) latent prints, the most common type, which are made when oil and perspi­ ration naturally present on fingertips are transferred to another surface but are invisible until developed through various techniques. DNA may also be obtained from fingerprints (see earlier discussion of touch DNA). The most common techniques used to recover latent prints consist of the application of powders, chemicals, and glue fumes. Although chemicals can be useful for identifying latent prints, they can affect DNA analyses. "Dusting" for prints involves the brush application of a fine powder to surfaces believed to potentially contain latent prints. The powder adheres to the oil and perspiration trans­ ferred from fingers and makes the prints visible. This technique is most likely to reveal prints when the surface is hard, smooth, and nonabsorbent, such as glass, painted wood, or metal. Powder of a different color can be applied to provide contrast with the surface being dusted. Fluorescent powder can also be used in a similar manner to enhance the visibility of latent prints.

Chemical methods can be used to recover prints from soft or more porous surfaces, such as paper or clothing. Various types of chemicals can be applied either by spraying the surface, through a process of fuming, or by dipping the object containing prints into a chemical solution. Another technique involves glue (or cyanoacrylate) fuming. With this method the object being examined for prints is either placed in a sealed tank and then exposed to the vaporized cyanoacrylate, which adheres to the print and makes it visible, or the fumes are a pp lied via a fuming wand.

Chapter 5 • Physical Evidence and the Crime Scene

Plain Whorl Central Pocket Loop

Douttf~ ~9P Whorl

In addition to these methods, laser technology has been used for highlighting latent prints on difficult surfaces. Regardless of the method used to recover prints, the visible prints first should be photographed and then "lifted" by placing adhesive tape over the print so that the powder adheres to the tape. The tape is then placed on a card that provides contrast with the lifted print, thereby preserving the print and making it visible for further analyses and comparison.

Locating quality latent prints is not an easy task and depends on the crime scene. Obvious places, such as door handles, drinking cups, and weapons, as well as less obvious places, such as telephones and toilet handles, should be examined for prints. Many recovered prints are of poor quality, making them nearly worthless as evidence. Fingerprints can be smeared or can become dirty, or the fingers themselves could have been dirty, all of which would obscure the individual characteristics of the fingerprints.

If fingerprints are recovered from a crime scene, elimination prints may need to be taken. Elimination prints are fingerprints of all persons known to have had legal access to the scene. These prints are then compared with the other recovered prints, and the ones that do not match may belong to the perpetrator.

The automated fingerprint identification system (AFIS) has made fingerprints more useful in identifying perpetrators. With an AFIS in place, whenever a person is fingerprinted by the police in that jurisdiction due to being arrested, applying for a particular job, or for some other reason, those fingerprints are entered and stored in the AFIS. Then, after a fingerprint is collected from a crime scene, it is scanned into the AFIS, and the computer searches the system, looking for prints with similar characteristics. The newest systems on the market today can search hundreds of thousands of prints within minutes; older systems require hours to search the same number of prints. The system may identify several prints that are the most similar in their pattern and unique characteristics. The print in question must then

121

Automated fingerprint identification system (AFIS): A database that contains fi ngerprints collected from various known sources; it is used to identify unknown fingerprints.

122 CRIMINAL INVESTIGATION

PHOTO 5.26: Latent fi ngerprints being recovered from a teller window after a bank robbery.

EXHIBIT 5.6

Example of Completed Ten-Print Fingerprint Card

LEAVE BLANK

~~­ V.ST-.FIR$1~~f-,Gl.F'U\

HUGHES, KEVIN LAMAR

CRIMINAL (STAPLE MERE)

0 0

GATSON, DANIEL LAMAR

01-24-1987 M

Mugshot File Name

0

510 165 BRO BLK

' .,,, Source: Federal Bureau of Investigation, United States Department of Justice Criminal Justice Information Services Division , Cla rksburg, WV 26306.

Chapter 5 • Physical Evidence and the Crime Scene

be manually compared with the "hit" print by a fingerprint examiner. It is in this manner that fingerprints recovered from a crime scene may lead to the identity of a perpetrator.

Prior to AFIS technology, fingerprints were used in several different ways. First, when a fingerprint was recovered from a crime scene, it was simply filed away until a suspect was identified through some other means, and then a comparison of that suspect's prints and the recovered prints was made. Second, if a suspect was already identified, a comparison could be conducted immediately. Third, a manual search could be made through the finger­ prints on file in that particular jurisdiction or on file with the FBI. No question, this process resembled trying to find a needle in a haystack, and rarely did it have a positive outcome.

Although the use of an AFIS certainly makes the processing of fingerprints much more efficient, there are several limitations to the technology. First, it can be costly to collect fingerprints from crime scenes and analyze them via an AFIS. Although at first glance it seems easy--collect fingerprints from a crime scene, enter them into the AFIS, get a match, and make an arrest-the process is much more time-consuming. Fingerprints are most likely to be available for recovery from burglary crime scenes, stolen autos, and certain robberies. However, given the sheer volume of these types of crimes in many jurisdictions, the routine collection and AFIS analysis of fingerprints may simply not be feasible. For example, in Houston there are approximately 20,000 burglaries, 10,000 robberies, and 13,000 motor vehicle thefts reported annually.36 If two hours were spent collecting and processing fingerprints in just three-fourths of the burglary cases, it would amount to 30,000 hours of investigative time and approximately $1.5 million. This could pay for the salary and benefits of at least fifteen additional officers per year. Expensive, indeed.

A second limitation is that a multimillion-dollar AFIS can be foiled by a pair of $0.59 latex gloves. That is, even if the perpetrator's prints are in the system because of a previous arrest, if the perpetrator is careful enough to not leave fingerprints, an AFIS may not be of any use. An AFIS may be able to compare glove prints, but the precision of these comparisons may be much less than with fingerprints .

Third, even if a perfectly clear fingerprint is collected from a crime scene, the perpetrator's print will not be identified if her or his prints are not in the system being searched. Compounding this issue is the fact that many of the larger police departments in the country operate their own systems. And, thanks to newer and less expensive models on the market, even some smaller police departments now operate such systems. Most states also operate an AFIS out of the state law enforcement agencies. The downfall with this arrangement is that these systems are most often self-contained; only the fingerprints collected in that juris­ diction are contained in that system. Thus, if a perpetrator's prints are held in one AFIS but are recovered by a police department in another jurisdiction, a match would not be obtained.

To improve the effectiveness of AFIS technology, in 1999 the FBI deployed a national fin­ gerprint database known as the Integrated Automated Fingerprint Identification System (IAFIS). In 2014 this system was fully replaced with the Next Generation Identification (NGI) system.37 Along with more than a hundred million fingerprints, the system also stores other biometric data, including photos, tattoos, scars/marks, and palm prints. Data in the system are provided by federal, state, and local law enforcement agencies from across the country and can be accessed by these agencies in their search for perpetrators. This expands dramat­ ically the number of fingerprints available to be searched to identify perpetrators.

As noted, most fingerprints from suspects are collected due to an arrest and are collected on ten-print fingerprint cards. Legally, in order to collect fingerprints, investigators must have either probable cause or the suspect must willingly submit to having his or her finger­ prints taken (see Hayes v. Florida, 1985).

SHOEPRINTS, IMPRESSIONS, AND TIRE TRACKS

Shoeprints are created when material from the bottom of shoes, such as blood or mud, is transferred to another surface, leaving an outline of the bottom of the shoe. Shoe

123

Next Generation Identification (NGI): A national fingerprint and biometric database operated by the FBI.

124 CRIMINAL INVESTIGATION

impressions and tire tracks are most often left in soft material such as mud or snow, and they reveal the outline of the shoe or tire. Shoeprints and impressions may reveal the per­ petrator's entrance to and exit from the crime scene and movements around the crime scene. It is also possible to determine from an analysis of the shoeprint or impression cer­ tain class characteristics, such as the size of the shoe and the make and brand of the shoe, as was the case in the 0.]. Simpson investigation. In some instances shoeprints and impres­ sions may reveal individual characteristics (see Exhibit 5.7). Tire tracks may reveal the direction of travel, the size and manufacturer of the tires, and possibly the make and model of the vehicle. In some instances tire tracks may be associated with particular vehicles.

PHOTO 5.27

PHOTO 5.28

-.

Chapter 5 • Physical Evidence and the Crime Scene

PHOTO 5.29

PHOTOS 5.27-5.30: Tire tracks, a transferred shoeprint, a shoe impression in snow, and a shoeprint cast. All of these may be useful evidence in an investigation.

Well-worn shoes may show wear patterns and other wear elements unique to those shoes (see Exhibit 5.7). Brand-new shoes will have only features that allow the make and size of the shoe to be determined. However, even with seemingly unique wear patterns, there is no scientific agreement about the number of individual characteristics needed to make a posi- tive association (to say that one shoeprint matches the other). 38 ·

Prints, impressions, and tracks should first be photographed and then, if possible, a cast of the impression or track should be made. If the impression or print is left in soil or mud, the recovery procedure involves pouring dental stone (a variant of the type of gypsum used to

125

126 CRIMINAL INVESTIGATION

Unusual Shoeprints

Notice how the shoeprint on the left is different from the one on the right. Such a pattern may provide an assoc iation with

a particular pair of shoes and person.

make dentures) into the impression. When the stone hardens, the mold reveals the outline of the impression. If the track or impression is in snow, the snow is first sprayed with a special wax to harden the impression, and then the dental stone is used.

TOOLMARKS A toolmark is any mark created when an instrument (e.g., pry bar, screwdriver) has contact with another surface (e.g., the wood on a windowsill). The marks left by a tool may indicate the type of tool, the size of the tool, and even the skill of the perpetrator (usually, the fewer the marks/damage, the greater the skill of the perpetrator). Through microscopic examina­ tion of the marks and a tool, a tool may be linked to a toolmark. Toolmarks are most commonly found around windows and doors in burglary cases. Toolmarks can be photo­ graphed, and casts can be made of the impressions.

BITE MARKS AND DENTAL EVIDENCE Dental evidence can take two primary forms: dental identification and bite marks. In both these instances, the fact that each individual has a unique set of teeth in terms of form, arrangement, dental work, and bite pattern makes dental evidence a potentially valuable form of evidence. The physical characteristics of bite marks and dental identification typi­ cally consist of the distance between teeth, the shape of the mouth/bite, teeth alignment, teeth shape, missing teeth, and wear patterns of the teeth. A primary means of identifying decomposed dead bodies is dental identification, during which dental radiographs of the individual are compared with those of the dead body. A match may be made on the basis of a comparison. Of course, this manner of identification is only possible if a dead body is suspected to be a particular individual and x-ray records are available for comparison.

Chapter 5 • Physical Evidence and the Crime Scene

PHOTO 5.31

PHOTOS 5.31-5.32: Toolmarks may be used by investigators to determine the type of tool, the size of the tool, and, perhaps, the skill of the perpetrator.

Bite marks can be either offensive or defensive. Offensive bite marks would be left on a victim by a perpetrator; defensive bite marks would be left on a perpetrator by the victim. Bite marks may also be an area from which DNA can be recovered. Bite marks are seen most often in cases of homicide, sexual assault, and child abuse. There are several methods of collecting bite mark evidence from victims and suspected biters: photographs, dental casts, clear overlays, computer enhancement, and electron microscopy. However, bite marks on the skin will change in appearance over time, and this may affect the ability to accurately link a bite to a particular suspect. The difficulties and likely errors in attempting to link a

127

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CRIMINAL INVESTIGATION

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PHOTO 5.33: Bite marks can be offensive or defensive. The analysis of bite mark patterns is an exactly inexact science.

suspect to a bite means extreme caution should be taken when using bite marks as individ­ ualized evidence.39 In fact, the analysis of bite mark patterns has been so fraught with error that some states have recommended such evidence not be allowed in court .40

BALLISTICS Various types of evidence are associated with firearms, and various examinations can be done on such evidence. The gun itself can be examined to determine its general condition and whether it is functional. Alterations in the functioning of the weapon can be determined, such as if it has been altered to fire in automatic mode. The trigger pull can be tested to determine the amount of pressure necessary to fire the weapon (potentially useful if a per­ petrator claims that the gun fired accidentally). Fired bullets can be examined to determine their caliber and manufacturer. An examination of shell casings may determine the caliber or gauge and the manufacturer. A suspect's DNA or fingerprints may be recovered from firearms and/or shell casings.41 Bullets that passed through a body may contain the victim's DNA and therefore associate the bullet with the victim. Also, one common and potentially useful form of evidence in crimes involving a firearm discharge is gunshot residue. Residue patterns may be found on a victim and used to estimate the distance of the muzzle from the victim. In addition, gunshot residue may be found on the hands or clothing of the individual who fired the weapon. Residue tests are commonly performed on individuals who were at

:

Chapter 5 • Physical Evi dence and t he Cr ime Scene

or near a crime scene around the time of a shooting and who are suspected to have fired the weapon. Residue is most likely to be found on the back of the hand in which the gun was fired, but this depends on many factors, including the type of gun.42

Another firearm examination involves test firing a gun to determine whether a recovered bullet was in fact fired from that gun. This comparison is done through the microscopic examination of the markings on the bullet caused by the bullet moving through the barrel of the gun. Although these markings are unique to each weapon, if a recovered bullet is deformed, a valid comparison is difficult to make, if not impossible. Factors such as corro­ sion and/or dirt in the barrel of the gun, the firing of a bullet that is smaller than intended for the gun, and different brands of ammunition can also affect the unique markings on a bullet.43 The Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF) operates the National Integrated Ballistic Information Network (NIBIN), which allows for the comparison of recovered bullets and cartridge casings with images of other bullets and casings that have been entered into the system from law enforcement agencies nationwide. By comparing the markings on bullets, crimes (shootings) committed with the same gun can be identified.44

When collecting firearm evidence, it first should be photographed and, if possible, finger­ printed (weapons and unfired cartridges) and examined for DNA. Firearms should be han­ dled with great care. A ring device that passes through the trigger guard should be used; this ring prevents contact with the firearm and preserves fingerprints or other evidence on the weapon itself. Weapons, bullets, and casings should be collected and packaged separately. The firearm, bullets, casings, and/or other firearm evidence should not be marked. Clothing sub­ mitted for gunshot residue examination should be packaged separately in paper envelopes.

FIBERS Any type of fabric or textile material contains fibers. Natural fibers include, for example, wool, cotton, glass, and fur. Synthetic, or man-made, fibers include nylon and polyester, among others. Fibers from one source are easily transferred to other surfaces, such as the transfer of fiber to fiber (e.g., clothing to clothing), fiber to skin, fiber to shoes, or fiber to

PHOTO 5.34: Shell casings are a commonly found type of evidence in crimes in which a fi rea rm was used.

129

National Integrated Ballistic Information Network (NIBIN): A national database operated by the ATF that contains bullet and cartridge casing images and is designed to link bullets/casings fired from the same gun.

130 CRIMINAL INVESTIGATION

vehicle. Examinations of fiber evidence can vary in sophistication. For example, a compar­ ison can be made between two fibers based on a relatively simple microscopic examination of the color, diameter, and other distinguishing characteristics of the fibers . A more precise examination may be made between fibers based on color through the use of microspectro­ photometry. This procedure essentially involves shining light on a fiber and recording the absorption of that light. Chromatography can also be used to identify the chemicals used to make the dye of the fiber, and comparisons can be made on this basis. However, even using the most sophisticated methods, fibers cannot be individualized to one particular source. 45

Fiber evidence is most often found in homicides, assaults, and hit-and-run offenses, and it may be found on clothing, skin, shoes, and carpeting, among other places. Fibers should be packaged in paper envelopes with sealed corners. When possible, the entire garment or textile should be submitted for analysis.46

SOIL

Soil consists of organic natural materials such as rock, minerals, and decomposing plants, and it may also contain man-made materials such as brick, concrete, glass, or paint. Examination of the color, texture, and composition of soils may allow for an assessment of whether the soils share a common origin.47 One of the most common scientific techniques of analyzing soil is the density gradient tube. In this procedure the densities of soil samples are analyzed via chemicals that separate the particles comprising the soil. If the pattern of sepa­ ration is similar in two or more samples, it indicates soil with consistent properties. Once again, despite using the best methods, soil cannot be individualized to one particular source.48

Soil evidence is most likely to be found on the bottom of shoes, in places where shoes may leave soil (e.g., the floors of vehicles, hard-surface walkways), on clothing, and on the tires, fenders, and body of vehicles. It is recommended that when soil samples are to be collected, they be taken as soon as possible. In addition, if it is present, soil should be collected from the immediate crime scene area and from the apparent entrances and exits of the crime scene. Samples should be collected from wherever there is a noticeable change in the color or com­ position of the soil. It is often necessary to collect numerous soil samples from a scene. A map should be drawn showing from where soil samples were taken. Investigators should not remove soil from recovered shoes, clothing, or tools. Paper bags should be used to package materials containing soil, and soil samples should be placed in plastic film-type canisters. 49

PAINT Paint is a pigmented polymer applied and adhered to various surfaces. Paint evidence may be found when paint has been transferred from one surface to another, either as wet paint or chips from dried paint. Paint may be found on tools or on the clothing of victims or suspects. Paint is often present as evidence in hit-and-run cases as it may be transferred from one vehicle to another or from a vehicle to a person who has been struck. It is also sometimes present in burglaries as paint may be transferred from a building to the perpe­ trator or from a building to the tools used to gain entry into it. Paint chips tend to be located in pants pockets and pants cuffs.

It is possible to compare microscopically the color and shape of paint chips or other sam­ ples. It is also possible to determine through the use of gas chromatography the chemical properties of paint to determine whether samples are from the same source. When paint fragments are able to be fit back into a known source, those paint fragments may be iden­ tified as originating from that specific source; it is only in this situation that paint can be individualized as originating from one particular source. 50 The FBI crime laboratory main­ tains a database of vehicle paint samples with which the color, year, make, and model of an automobile can be determined by analyzing recovered vehicle paint samples. When paint samples are collected, it is necessary that the paint be chipped off the surface, as opposed to scraped off, in order to preserve the layer structure of the paint. With hit-and-run victims,

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Chapter 5 • Physical Evidence and the Crime Scene

the victim's clothing should normally be submitted for laboratory analysis, as should entire vehicle components (e.g., bumper) that contain paint evidence. Paint particles should be packaged in pillboxes or vials. Plastic bags, cotton, or envelopes should not be used. 51

Control paint chips must be collected from the suspected source of the evidentiary paint. 52

GLASS

Like paint, glass is most often found at hit-and-run and burglary crime scenes. Through microscopic examination of glass particles and their density and refractive properties, the type of glass can be determined and can be compared to a particular (broken) source of glass. In addition, pieces of glass may be fit into a broken source of glass, such as a window; thus, glass may be individualized as originating from one particular source. Glass fracture exam­ inations can determine the direction of breaking glass, and the location of broken glass may also be of evidentiary value. If the perpetrator touched the glass, DNA and/or fingerprints may be recovered. Glass particles should be packaged in plastic containers. Larger pieces of glass should be packaged in solid packing containers with cotton packing material. 53

BLOOD PATTERN ANALYSIS

The interpretation of bloodstain patterns can be useful in helping investigators understand how a crime occurred. Bloodstain patterns may be present in homicides, sexual assaults, burglaries, and hit-and-run accidents. As explained by the National Research Council,

[d]ried blood may be found at crime scenes, deposited either through pooling or via airborne transfer (spatter). The patterns left by blood can suggest the kind of injury that was sustained, the final movements of a victim, the angle of a shooting, and more. Bloodstains on artifacts such as clothing and weapons may be crucial to understanding how the blood was deposited, which can indicate the source of the blood. For example, a stain on a garment, such as a shirt, might indicate contact between the person who wore the shirt and a bloody object, while tiny droplets of blood might suggest proximity to a violent event, such as a beating. 54

PHOTO 5.35: Fingerprints or touch DNA may be recovered from glass.

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132 CRIMINAL INVESTIGATION

DIGITAL EVIDENCE

Electronic devices such as cell phones and computers may provide a wealth of information regarding communications, schedules, travels, and criminal behaviors, and therefore they are potentially valuable sources of evidence in criminal investigations. The content of devices can be extracted and analyzed, the location of devices can be determined, and link­ ages between devices and Internet sites can be established. Chapter 9 provides more details about digital evidence.

VIDEO EVIDENCE

Video can be an extremely useful form of evidence. If a perpetrator is captured on video, there may be little doubt about who committed the crime. Video recordings may be enhanced to maximize the clarity of the images captured. In addition, still photographs can be obtained from video images. Video images are most often available as evidence in rob­ beries of locations that feature surveillance, such as an automated teller machine (ATM) or a convenience store. In one case a perpetrator entered a home at night and assaulted a young woman. He took her ATM card and code and proceeded to withdraw cash from an ATM machine. Police traced the use of the card to the machine and obtained a video of the man using the card. A still photograph of the suspect was publicized and the identity of the man was discovered. His DNA then linked him to the assault.

Some potential limitations of surveillance video are that it may not be of sufficient quality to be useful, cameras may not be placed correctly to capture the crime or to obtain a good view of the perpetrator, or the surveillance system may be out of order. These issues could limit the value of the resulting evidence.

PHOTO 5.36: Bank video surveillance cameras usually provide high-quality images. Here a man dressed as a woman is demanding money from the teller. Details of the perpetrator's wig, face, purse, and other clothing are clear.

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Chapter 5 • Physical Evidence and the Crime Scene

PHOTO 5.37: Some businesses still rely on older video equipment that provides low-quality images. Here a store camera captured an image of a soon-to-be car thief. Obviously, this image was worthless as evidence.

QUESTIONED DOCUMENTS/HANDWRITING ANALYSIS

Written documents can be examined in many ways. The content of the writing can be ana­ lyzed, as can the style and mechanics used. The penmanship can be studied. Documents can be examined in order to associate a suspect with a written document or to associate written documents (and crimes) with each other. Paper can be analyzed as to its type, brand, and manufacturer. The ink used to write the words can be analyzed to determine the type of writing instrument used (e.g., ballpoint pen, fountain pen) and allow for a comparison of ink samples.

Most useful may be the comparison of a written document in evidence with a writing example from an identified suspect to see if the handwriting is consistent across the two samples. In this case several procedures are recommended: 55

• Use the same type and size of paper, request handwriting or hand printing, and give verbal and written instructions as to what the suspect is to write.

• The writer and the witness to the writing should initial and date each page of writing.

• Do not allow the writer to see the writing that is in question and being compared.

• It may be necessary to obtain several repetitions in order to obtain a natural and valid writing sample.

• Writing examples from the right and left hand should be obtained as well as writing containing both upper- and lowercase letters.

• If possible, obtain other existing writing samples from the suspect, such as notes or letters.

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134 CRIMINAL INVESTIGATION

The difficulty with handwriting analysis is that the handwriting of a person is not always the same. Furthermore, as with toolmarks, fingerprints, and bite marks, it is not valid to state a percentage probability that a handwriting example was written by a particular sus­ pect; there is no basis on which to conclude how common handwriting characteristics are in a given population.56

DRUGS Drugs are commonly seized as evidence in criminal investigations and can come in many forms, including pills, powders, or liquids (see Exhibit 5.8). The forensic analysis of drugs is normally quite routine; gas chromatography and mass spectrometry are usually used to identify the drug, if it is a drug. Also important is determining the total weight of the drug, as criminal penalties are often based on this; the total weight of a drug is the pure drug plus anything it may be mixed or "cut" with. However, there must be a " useable quantity" of the drug present in order for a violation of the law to exist. The evidence should be pack­ aged in plastic bags that are heat sealed or can be resealed. The drug test field kit should not be submitted with the evidence. 57