Working a Scene Scenario Role-Play Activity

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1Forensic Science and Criminalistics

Associated Press

Learning Objectives After reading this chapter, you should be able to do the following:

▪ Define forensic science and how it contributes to a case, as well as explain the CSI Effect and the scientific method.

▪ Summarize the history of forensic science and contributors to the field.

▪ List and describe some forensic science specialties.

▪ Identify the elements of a forensic investigation, how physical evidence can be produced, and forensic analysis.

▪ Describe the work and work product of a forensic scientist.

▪ Describe the U.S. court system, and the key rulings on physical evidence admissibility through expert testimony.

▪ List and discuss major issues in forensic science today.

2Crime Scene Processing and Analysis and Forensic

Technologies

SEInnovation/iStock/Thinkstock

Charles Steele, Purdue University Northwest

Learning Outcomes After reading this chapter, you should be able to

▪ Contrast the differences between the types of improvements in quality systems.

▪ Identify actions to take when initially responding to a crime scene.

▪ List and describe the steps involved in processing a crime scene.

▪ Explain the factors and types of information required to reconstruct a crime scene.

▪ Provide examples of technology used to collect and analyze evidence.

Introduction

Introduction Crime scene investigations are driven by the principal expressed by Dr. Edmond Locard (1877–1966), who said that every contact leaves a trace. As people interact with other people, places, or things, they will inevitably leave something of themselves behind and take some- thing of the other with them (Saferstein, 1998). It is a crime scene investigator’s job to find these traces and reassemble them into a complete picture that can tell the courts and jury what happened.

The forensic investigation of crime scenes requires a wide range of skills and technologies. Although there are common aspects to all crime scene investigations, every crime is unique. Skilled crime scene investigators must therefore have a sufficient breadth of knowledge to correctly evaluate and satisfy these needs.

Forensic investigations typically begin with crime scene processing, which is the first topic of this chapter (Technical Working Group on Crime Scene Investigation, 2000). The success or failure of a criminal investigation is often dictated by how well crime scene investigators do this job. Crime scene processing is all about recognizing, documenting, preserving, and col- lecting potential evidence and submitting it to the laboratory for analysis. Crime scenes need to be thoroughly documented via notes, sketches, photographs, video, and laser scanning to make sure that no aspect of the environment is lost. Specific procedures need to be followed to protect and preserve the physical integrity and legal value of the evidence. There is only one chance to get this right; once a crime scene is released, it is no longer protected, so there is no way to control what changes occur within it. Therefore, investigators cannot go back and correct errors or omissions.

Well-documented and proven methods for investigating crime scenes are often a component of law enforcement training. Unfortunately, no matter how complete these methods, unantici- pated issues and problems will occur. Crime scenes are often messy. The investigative team may not have experience working with each other. Priorities and needs may not be immedi- ately obvious. The boundaries of the crime scene itself may not be fully understood before the investigation begins.

Consider a situation in which a person is found dead on a bed, in a bedroom, in a house. When approaching the scene, what is the priority? Should the first responder check the body first or secure the scene? A decision must also be made as to what exactly is part of the crime scene. Is it the body, the bed, the bedroom, the house, or the entire property? Once these decisions are made, an order of operations must be established so that evidence is collected in the most efficient and least destructive way.

After a crime scene is processed, the investigation moves to crime scene analysis, in which the crime is reconstructed. Based on the all the data—investigative findings, laboratory results, and even medical tests (and/or medical examiner’s results, in death cases)—a reconstructive theory can be formed. In practical terms, investigators cannot wait until all the data is com- piled before considering theories of the case. Blood patterns may be interpretable and pro- vide insight into movements or actions. Weapons found at the scene may correlate to wounds. Cartridge casing might indicate the presence and number of shooters. Pattern evidence like footprints and tire marks inform investigators about the presence of involved people and vehicles. Crime scene analysis can take a long time to complete, and each piece of information

Section 2.1Education

helps focus the investigation. It is, however, important to remember that any theory formed from early crime scene analysis may need to change as additional data are compiled.

What follows in this chapter are specific types of crime scenes, initial steps to take, legal con- siderations, typical steps for processing, and an introduction to some of the various equip- ment and techniques that can be used when investigating a crime scene.

2.1 Education Historically, most crime scene investigators were law enforcement personnel with little or no scientific training. This is not to say that these people were not good at their jobs. Non- scientist crime scene investigators brought us innovations such as forensic photography and the understanding of the temperature dependence of cyanoacrylate-developed fingermarks (Weaver et al., 2009). But forensic science is an evolving field.

Practical Training Recognizing that crime scene investigations had errors, omissions, procedural failures, and insufficient technology, national bodies like the NAS identified a need to increase scientific and procedural rigor (National Research Council, 2009). The resulting changes are working their way into all areas of forensic science, including crime scene investigations. As of mid- 2018 almost all specialized crime scene investigation units are police personnel, but spe- cialized scientific training is increasingly required for these jobs. Many police agencies now require applicants for crime scene unit positions to have a higher level of education than previously needed, including in some cases a college degree.

Fortunately, some colleges and universities now offer forensic science degrees, and many more offer some type of crime scene analysis class. In all likelihood, if you are reading this book, you are taking such a class. Larger police agencies tend to have formalized training programs for crime scene personnel. Professional organizations also offer regular training classes and seminars.

In most cases, however, unless the student is a police department trainee , the actual crime scene portion of the training will be limited to mock crime scenes in a staged environment. These staged environments allow students to learn how to examine a crime scene, collect evi- dence, and utilize the relevant technology in a safe environment, where they cannot damage an investigation.

Think About It

Does every crime have a crime scene?

Try to envision a crime that does not have a crime scene. Now, imagine that you are a forensic expert who needs to find evidence. What are you processing, and where is it? Now once again, consider—does every crime have a crime scene?

Section 2.1Education

Although useful, mock crime scenes are limited in that students must be able to ignore any distractions happening outside of the staged area. In any staged location, there will be real-world contamination. Mock crime scenes are also limited by the creativity of the instructor. Still, when properly done, mock crime scenes can introduce students to the realities of working in a crime scene.

This experience can be improved with the use of computer simulations. Immersive virtual environment training simulations make it possible to more uniformly cre- ate and curate artificial crime scenes. Stu- dents can now walk through a virtual crime scene and document evidence. Such simulations have the advantage of being consistent and easy to use. All that is required is an open space and a proper computer.

Quality Control Because consistency and accuracy are of major concern in forensic science, it is now required that any accredited educational program teach quality control. Following standard operating procedures (SOPs) that meet the guidelines of internationally recognized quality systems is a common way to maintain consistency of practice and ensure the best results. However, there are multiple approaches to quality systems, and not all are equally appropriate. Therefore, care must be taken not to follow other systems blindly or inappropriately.

Most production-based quality control systems are built on the principals laid out in Six Sigma. They maintain quality by monitoring factors that contribute to a final product and adjust these factors until an acceptable error rate is achieved. However, crime scene analysis, like medicine, should not allow for an acceptable error rate. Instead, forensic science should follow laboratory-based quality control systems, which are typically based on guidelines pub- lished by the International Organization for Standardization (ISO). These approaches to quality control are driven by a best practices model and rely on the input of day-to-day prac- titioners for continual improvement.

Universal Images/Superstock Mock crime scenes can help students get hands- on practice in forensic environments.

Think About It

Mock crime scenes are a commonly used training method. If you were going to stage a crime scene for training purposes, how might you do it? What details might you include, and why?

Section 2.2Initial Responses to Crime Scenes

Corrective actions, preventative actions, and improvements are used to identify real and potential areas for improvement in a typical quality system (Indiana State Police Laboratory Division, 2017). Corrective actions are submitted when there is an actual error or system breakdown. Preventative actions are similar but are submitted when a situation arises that could lead to an error. An improvement is submitted when a better way to do something is discovered. Once a corrective action, preventative action, or improvement is submitted, it will be evaluated according to a standard process, and if the reviewers agree that the issue war- rants a change, the relevant SOP will be modified. Therefore, crime scene investigators should be well versed in the SOPs of their agency and stay abreast of latest innovations across the industry.

Regardless of the training vehicle, students must come away appreciating the best practices for moving and operating within a crime scene. We will now explore the steps to take when encountering and investigating a crime scene.

2.2 Initial Responses to Crime Scenes There are many ways to classify a crime scene. It might be indoor, outdoor, or in a vehicle; it might be on public or private property. Within these various locations, crime scenes are further classified according to the type of offense believed to have been committed. Prop- erly identifying the type of crime scene encountered is important because it dictates how the investigation must proceed. Factors like setting up security, deciding whether a war- rant is needed, figuring out how long a scene might need (or be able) to be held secure, and determining what equipment and safety precautions are needed all depend on a crime scene’s type.

Throughout this chapter, the discussion will focus on crime scenes that are places. However, a crime scene may not always be a place. Computer-based crime is a major concern for law enforcement and security professionals. In this arena, the crime scene is the virtual world of hard drives and data storage. This topic will be discussed in more detail in a later chapter. A crime scene can also be a person. Violent or sexual assault leave leaves trace evidence on victims. Medical personnel typically collect evidence from living victims, while medical exam- iner personnel typically collect evidence from deceased victims.

A location-based crime scene is secured to protect the evidence within defined perimeters. Outside the security boundaries, the environment is fluid and subject to a lot of activity. Inves- tigators and support staff congregate in this outer area. In this way, necessary activities like staging gear and equipment, planning activities, and parking vehicles do not interfere with or contaminate the evidence.

The initial response to any crime scene depends on emergent needs. For example: Is there a reason to believe that perpetrators might still be present? The responding officer usually does not know the answer to this question. Officers must exercise extreme caution when respond- ing to a scene without reliable information, as is common when responding to a 911 call. They may need to disarm and detain a suspect, and the officers’ safety is a primary concern.

Section 2.2Initial Responses to Crime Scenes

Beyond the possibility of encountering an armed suspect, initial responders also need to be wary of environmental hazards or hidden traps. Hazardous chemicals can be found in many environments. A crime scene need not be an illicit drug lab to contain hazards. Acids, poisons, and flammable chemicals have many legal uses and tend to be poorly stored. In addition, the United States has a strong gun culture and numerous hunters and sportsmen. Deadly weap- ons can therefore be present almost anywhere. The list of potential hazards includes guard animals, biological hazards, poorly maintained structures, and many more.

The initial responder must quickly establish who is at a crime scene, assess their condition, and determine whether medical help is needed. Once the hazards are assessed, the officer needs to determine if there are victims who might need emergency medical assistance. If paramedics need to tend to an injured person, the officer must do his or her best to make sure evidence is not destroyed. The well-being of injured persons is of the highest importance. This means that at times, some evidence will be lost or contaminated.

When the scene is known to be free of potential dangers and wounded persons, the next pri- ority is to secure the scene. First responders must do their best to determine the perimeter of the scene. Their primary goal is to keep people out of the scene until properly trained crime scene personnel can respond. The actions of the first responders will cause changes in the scene. If the conditions are not recorded immediately, they may be forgotten, and important details can be lost. Therefore, responders should note a scene’s initial conditions and record these as soon as possible.

The time of day, the weather, whether doors are locked or unlocked, whether lights are on or off, and any unusual features, odors, or sounds should all be documented. First responders should also keep track of who has been inside the crime scene before it has been fully secured. They should also note who is nearby, since suspects have been known to be present as spec- tators and because after a crime scene has been secured, it may be necessary to extend the perimeter to include a larger area.

The takeaway here is to stay safe, establish control, and document everything. Crime scenes can be dangerous. Activities in and around the scene may be critical to the investigation. Secu- rity barriers need to be maintained until investigators are ready to release the scene.

Note that protections guaranteed under the Fourth Amendment of the U.S. Constitution require that crime scenes that occur on private property are subject to a property owner’s

Think About It

How hazardous is an ordinary environment?

Consider an average home owner’s craft area or workshop. How many potential hazards can you think of that would warrant special care if that area were to become a crime scene?

Section 2.2Initial Responses to Crime Scenes

discretion. If the owner asks the police to leave, in most cases they must do so until a search warrant is obtained. There are specific exceptions to this rule called exigent circumstances, which will be discussed shortly.

The Fourth Amendment There is an important constitutionally based body of law surrounding searches and seizures of places and persons; investigators and police officers must know it well. It is rooted in the Fourth Amendment to the U.S. Constitution, which states:

The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no War- rants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.

This seemingly straightforward amendment deeply affects the actions of law enforcement, and as a result, there is substantial case law around it. Citizens have a “reasonable expectation of privacy,” and the most protected premises are one’s person, one’s home, the area imme- diately surrounding the home (called the curtilage), and one’s vehicle. For the purposes of a crime scene investigation, a home can be considered off limits to a search without a warrant unless there is an ongoing emergency, the owner consents, or there is no one to object. The same may be true of the immediate surrounding area and any vehicles on the property. But there are no such limitations on searches in public areas. Additionally, in general, a search warrant is needed to search a person or to take blood or other intrusive specimens. A war- rant is issued by a judge or magistrate following an affidavit by an officer or investigator that provides supported probable cause to believe the search will reveal evidence of a crime. A search warrant is not given so that officers can look to see if there is any actionable evidence. It must be known in advance that there is probable cause that the search will yield evidence of a crime.

As mentioned above, however, there are exceptions to the need for a warrant. When circum- stances would lead a reasonable person to decide that entry or another immediate action is necessary to prevent people from being hurt, evidence from being destroyed, or a suspect from escaping, officers may act in advance of getting a warrant. These are called exigent circumstances, and in practice they can be difficult to determine (Cornell Law School, n.d.). Courts across the country have routinely denied the use of evidence from exigent searches when the judge decided that the need was not present.

The U.S. Supreme Court clarified the concept of exigent searches in Missouri v. McNeely (2013). In this case the court stated:

A variety of circumstances may give rise to an exigency sufficient to justify a warrantless search, including law enforcement’s need to provide emergency assistance to an occupant of a home . . . engage in “hot pursuit” of a fleeing sus- pect . . . or enter a burning building to put out a fire and investigate its cause.

Section 2.2Initial Responses to Crime Scenes

In addition, although invasive searches of a person without a warrant are generally prohib- ited, the police can search a person prior to or as part of an arrest. This is known as a search incident to an arrest. This search-incident rule is in place to protect the police from being attacked with hidden weapons.

Other exceptions also exist, such as the plain-sight exception. If an object is in plain sight, and the police officer has the right to be where the item is seen, no war- rant is needed to seize it. There is also a community caretaking exception, in which police may take charge of someone’s prop- erty to hold it in a secure place for them because they are unable to keep it secure. Finally, as mentioned earlier, an owner of a vehicle or property can consent to a search.

Police officers and crime scene investiga- tors must be cautious about searches and seizures to ensure that any evidence they obtain is later admissible in court. Evi- dence that is seized illegally will not be admitted.

Experienced crime scene investigators must learn about warrant requirements and how to apply them to specific cases. Even with experience, nuances can be difficult to correctly inter- pret. Consider a scenario in which a murder suspect is a homeless person living under a state highway bridge. The bridge and the area under it are clearly public property, so the investiga- tors determine that they do not need a warrant. They seize the suspect’s property and find evidence related to the murder. It sounds reasonable, but a conviction in a case like this is likely to be reversed on appeal. Even a cardboard box under a highway can be a home and is therefore protected under the Fourth Amendment.

Similarly, having an incomplete warrant can be the same as not having a warrant at all. Con- sider a situation in which investigators properly request and are granted a warrant to search

Think About It

The need to abide by the Fourth Amendment and obtain warrants is a serious issue. Do you think the law is beneficial or detrimental to crime scene investigations?

Will Powers/Associated Press Officers must serve a search warrant issued by a judge in order to enter a home without permission of the home owner or resident.

Section 2.2Initial Responses to Crime Scenes

a home but accidently omit any reference to or mention of an unattached structure like a shed or garage. In such a case, evidence found in any unattached structures may not be admitted to trial, since no permission or authority was granted to search them.

Emerging technologies are further complicating the concept of reasonable expectation of pri- vacy and probable cause. Early research promotes the idea that the structure and appearance of a person’s face can be inferred from DNA (Curtis & Howard, 2018). Some estimates suggest that this technology will be viable for investigative use by 2024. Early opponents are already suggesting that this technology represents an extreme form of profiling and should not be the basis for a valid warrant. Proponents counter by saying that the image of the face would be an investigative tool, not a confirmatory one. After all, if a suspect is found from a sketch based on DNA, that same DNA can be used to positively identify or exonerate the person.

It is clear why many people argue that DNA-based data is personal and should be protected. But what about less invasive information? In 2004 investigators placed a Global Positioning System (GPS) tracker on a Jeep Grand Cherokee belonging to Antoine Jones without a valid warrant. The case was contested all the way to the U.S. Supreme court (United States v. Antoine Jones, 2012) where it was decided that GPS installation fell under the restrictions imposed by the Fourth Amendment and was unconstitutional without a warrant.

That still leaves the question of whether passive GPS tracking data can be used without a war- rant. GPS navigation and social media location tags are becoming more prevalent. Millions of people use cell phone apps that plan out their journeys, mark their paths, track their steps, or simply let the world know where they are. Millions more have their movements followed without their conscious knowledge. Whether deliberately or accidentally catalogued by a sus- pect, such data can be invaluable to investigators trying to reconstruct the events of a crime. But is it protected under the Fourth Amendment? In June 2018 the Supreme Court decided in Carpenter v. United States (2017) that accessing historical cell phone data without a valid war- rant violates the Fourth Amendment. Crime scene investigators are bound by what the courts determine is legal. Sidestepping these rules, whether intentionally or unintentionally, will often result in evidence not being heard by a jury.

Think About It

Do you think law enforcement should be able to track a person’s movements by way of a GPS unit attached to a vehicle or by way of cell phone without the person’s knowledge? Law enforcement could argue that this is no different from having the person followed, except that it is a lot less expensive. Do you think you have a reasonable expectation of privacy regarding your whereabouts? If you are willing to let Facebook or your cell phone provider track you, have you given up your expectation of privacy?

Section 2.3Steps in Crime Scene Processing

2.3 Steps in Crime Scene Processing Depending on the type of crime and the department’s resources and policies, scenes may be searched and processed by police officers, detectives, or specialized units. Only large depart- ments have the resources to maintain specialized crime investigation units. No matter who is processing a crime scene, there are common steps that should be followed.

Step 1: Secure the Scene, Do an Initial Survey, and Recognize Evidence The major purposes of scene security are to limit access to the scene, avoid introducing extra- neous marks and trace materials at the scene, and reduce the possibility that useful evidence will be altered or destroyed.

The purpose of the initial survey is to understand what evidence is present throughout the scene and to formulate a hypothesis about what may have occurred. The more complicated the case and scene, and the more serious the crime, the more time investigators will spend surveying the scene. The initial survey allows the team to decide their next steps, divide up the tasks, and proceed in a logical order. Video footage may be taken during the initial survey to record initial conditions as accurately as possible and to give others who do not have access to the scene a chance to see it. The survey should give the investigators an idea of how much searching, documentation, and evidence collection will be required.

Step 2: Search the Scene All areas of the scene should be systemati- cally searched for any possible evidence. The initial search results and working hypothesis should guide the search team. If a suspect is not present, part of under- taking the search is to find evidence that can connect a person to the scene. Such evidence could be blood, body fluid resi- due, fingerprints, footwear indentations, or automobile tire impressions. Keep in mind that if the person in question is a regular occupant of the premises, proving a connection will not likely mean much.

Investigators may also be looking for evi- dence of corpus delicti—evidence that supports the commission of a crime. This type of evidence is often found at a loca- tion related to a suspect rather than at the scene of a crime. For example, missing property found in a suspect’s residence might connect that person to the scene of

John Raoux/Associated Press Scene searches are critical to an investigation; this is when evidence is found and collected. In addition to the examples mentioned in the text, what might investigators be looking for?

Section 2.3Steps in Crime Scene Processing

a burglary. A weapon may link a suspect to an assault. Flammable liquids might connect a suspect to an arson fire.

Step 3: Document the Scene and Evidence Documentation involves two aspects: documenting the scene and documenting the evidence. The detailed search should have revealed what the investigators consider evidence. This may include patterns like blood spatter, overturned furniture, or out-of-place objects, and it could include individual items that will be collected later.

Documentation is perhaps the central reason to investigate a crime scene. Classic documenta- tion methods involve notes, sketches, and photography; to these we can easily add videography and virtual reconstruction. Certain information should be included with all documentation:

• case number • date • time • location • person responsible for documenting evidence (sketcher, evidence collector, etc.)

Notes Notes are records of observations at scenes that cannot be readily photographed, sketched, or video recorded. They may be handwritten, keyed into a computer or handheld device, or audio recorded. As mentioned earlier, first responders should make notes about the scene’s initial condition. The notes will form the basis for the note taker’s later report, a formal ren- dering of what was observed in connection with the investigation.

Some authorities suggest several logs be kept while a scene is investigated. First is the secu- rity log. At a minimum, this log should record who was inside the secured area of the scene; it should catalog the entry and exit of every person. It has been suggested that a continu- ously running video camera be set up at a certain distance from the entry/exit point to act as the security log. A photography log should also be kept. This log is a written record of every photograph taken. Finally, there is the evidence log—a written record of every item seized from the scene, complete with a brief description, assigned number, and name/initials of the person who seized it.

Sketches, Location Mapping, and Laser Mapping Sketches are useful for preventing perspective errors caused by camera orientation of photo- graphs and videos. Accurate sketches require the use of tape measures and other measuring devices that may interfere with the scene if one is not careful. Alternatively, some success has been had with location-tagged photographs, which can be combined with computer-aided drafting (CAD) system software to reconstruct a crime scene with a high degree of precision.

Either of these techniques has its roots in drafting and technical drawing. Proper sketches use exact measurements to accurately represent the perimeters of the scene and the position of its objects. When a sketch or image map is properly done, a crime scene can be reassembled from its data.

Section 2.3Steps in Crime Scene Processing

To accurately specify an object’s location, measurements between two fixed points are required. If the scene occurs in a square or rectangular room, or in a space with other per- pendicular reference lines, then measurements from the two will uniquely place the object (essentially specifying x- and y-coordinates on a graph). Sketches made at the scene are called rough (preliminary) sketches.

The data will later be used to make a smooth (finished) sketch. In a smooth sketch, a scale is adopted, in which 1 inch might represent 2 feet, for example. After the scale is set, measure- ments are not included because everything is drawn to scale. Extraneous items—those not pertinent to the case—can be left out of the smooth sketch to avoid clutter. Like every product of a crime scene investigation, sketches should contain the case number, the date, the loca- tion, the name of the sketcher, and if applicable, the name of the measurer.

Most sketches will include a floor plan. If it is necessary to include information from a room’s walls or ceiling—such as blood or blood patterns—a cross-projection sketch can be made. Here, the sketcher “folds out” a room’s walls and ceiling onto a flat surface to record the infor- mation. In this way, three-dimensional information can be sketched in two dimensions.

Location mapping takes a different approach. Instead of measuring the perimeter and loca- tion of objects from an established reference point, each image is imbedded with a meta-tag that pinpoints its location on an absolute grid. This method requires the presence of fixed calibration points but eliminates the need to drag measuring tape across the scene. An advan- tage to location-mapped images is that they integrate easily with CAD software and can be used to digitally reconstruct a scene.

Many CAD systems are also easily integrated with laser mapping. Similar to location-tagging photographs, laser mapping uses a stand-alone laser with an integrated camera. As the cam- era photographs an object, the laser precisely measures its location. These systems are light- weight and relatively inexpensive. Laser mapping has an advantage over older technologies in that it makes it possible to measure spaces that are hard or in some cases physically impos- sible to access. Some systems even run from a cell phone app.

Laser scanners are another recent technological advancement in use at crime scenes. These scanners utilize a rotating pulse laser and mirror to take millions of measurements. The tech- nology is similar to a highway patrol speed gun, except that in this application the target is stationary and the gun is moving. As the laser is rotated around all the degrees of a sphere,

Think About It

Do you think CAD programs and computer-based reproductions and images are more valu- able to investigators and ultimately jurors than sketches and photographs? What are the pros and cons of each?

Section 2.3Steps in Crime Scene Processing

laser pulses are fired and bounce off objects, reflecting a portion of the beam back to the detector. Based on how long it takes a beam to return, a computer can calculate how far away the surface of reflection is from the laser base.

The point of reflection is calculated via right angle geometry, and a point cloud is generated showing where the solid obstruction is in three-dimensional space. Some systems can even incorporate color and texture from photographs. These systems are easy to set up and use.

Taking Photographs and Videos Even as imaging technology improves, photographs and videos are still among the most important methods of recording what a crime scene looks like. There are technical and scene guidelines for photo- graphing scenes and evidence that refer to cameras, lenses, and technical issues in photography itself. Crime scene photogra- phers must be familiar with these guide- lines (National Forensic Science Technol- ogy Center, n.d.a).

Scene photography guidelines are fairly straightforward and usually recommend an approach using overall, midrange, and close-up photos of each subject. The over- all picture should provide a wider per- spective of the subject; midrange should be a closer shot that provides more detail; close-ups should be taken to show small details. Using a flash is recommended because things visible to the eye in low light are not always captured in a photo without a flash. Outdoors, shadows that interfere with the clarity of a photo can be corrected using fill flash, a flash that fills in light where the shadows are. Generally, front lighting should be used for photos, since backlighting, or shooting into the sun, almost always causes problems. Side lighting is recommended for showing the details of three-dimensional indentation impressions because it creates just enough shadow to maximize pattern details, while front lighting tends to wash them out.

Photographs must be taken of the overall crime scene and any patterns that are present. Keep in mind that some patterns—like the way furniture is arranged or disturbed in a room—can- not be collected except by photo and video. Once the scene is released, these will be the only records of that pattern. Additionally, photos showing the evidence in relationship to the larger scene must be taken. Evidence items must be photographed, both at a distance and close- up, with and without a label or numerical marker. Photos without labels show an unaltered scene, which is important to the investigation. The same rule holds for placing a scale into a picture—one picture without the scale, then another with it. Evidence that will be collected is

Cultura Limited/Cultura Limited/Superstock While photographs are an extremely helpful type of documentation, they cannot duplicate elements like scale. Different angles can change the way things appear in photographs.

Section 2.3Steps in Crime Scene Processing

often marked by numbered placards. The placard numbers correspond to the items’ numbers in the evidence log that is submitted to the lab.

It was traditionally recommended that the scene photographer maintain a log that listed each picture taken, the photographic conditions, and the settings used, such as shutter speed and f-stop. That is no longer necessary. Most photography is digital, and it is easy to keep an elec- tronic record of photographic conditions. Furthermore, if the camera is set on an automatic mode, the camera will select some or all of its own settings. In this case it is not necessary to record all of the camera’s settings, but it is still a good idea to keep a record of photographs taken in a photo log.

Normally, people view objects under some form of white light. In these conditions, things that are of similar colors will blend in with each other. One of the advantages of photography is that by adjusting the light or adding a photographic filter, it becomes possible to show things otherwise invisible to the human eye. This works because what people see as a single color is really a combination of many different wavelengths of light hitting the human eye. By chang- ing which wavelengths are present or by blocking some of the wavelengths that reflect off an item from entering a camera lens, color differences can be shown. This phenomenon is referred to as forced metamerism, and it makes it easier to separate objects from their back- grounds in photos (Steele, 2015).

Even when crime scene photographs are not collected with different-colored lights or optical filters, computer imaging software can create a similar effect by altering the wavelength com- ponents. This is simply an application of color correction; anyone who has used computer art programs will be familiar with this technique. Image enhancement is another common technique that can improve the quality of the photo, revealing details that may be invisible to the human eye. However, there is a risk of altering an image so much that its appearance is not true to the captured image. Therefore, an unadulterated version of each photo should always be kept for reference. In addition, the photographer or image analyst needs to record how an image has been altered and provide the reason why.

Given the increasing importance of image evidence, image alteration is a significant issue. Digital photography experts can tell if an image has been edited by accessing information within the image file. Sometimes there are reasons to alter an image’s exposure, brightness, contrast, color, or magnification, which might enhance a detail the photographer was trying to capture. There is nothing wrong with changing an image, as long as the photographer is forthcoming about it.

Video recording is a supplementary type of photography. As mentioned earlier, a video record- ing can act as a security log. Video recorded inside the scene can also be shared with persons

Think About It

Do you think evidence looks the same in pictures as it does in real life? Could photographs be manipulated to alter the evidence?

Section 2.3Steps in Crime Scene Processing

outside the secure area, reducing the number of people potentially contaminating the crime scene. Good-quality video can also provide a way for the jury to see the scene, if doing so is believed to be helpful and permitted by the court.

As with photography, there are some guidelines for recording video of a crime scene. The camera should be held as steady as possible. A tripod or monopod should be used when pos- sible and practical. It can be helpful to zoom in and out, but zooming should be done slowly and with a specific purpose. If the video camera has a built-in clock, it should be set to corre- spond to the master clock used to record all times in the crime scene documentation. Failing to synchronize clocks can lead to contradictions later—such as if a video recording began at 9:36 a.m. but the team did not arrive at the crime scene until 9:44 a.m. Another issue to pay attention to is sound or narration. Narration is helpful if a narrator speaks slowly, informa- tively, and in an unemotional voice. Video recorder microphones are very sensitive and tend to pick up background noise and comments that may not sound professional to someone in court. To avoid this issue, some crime scene video instructors suggest not using the micro- phone or narration. The video record should contain the case number, date, time, location, and name of the videographer.

Step 4: Identify, Collect, and Preserve Evidence Following documentation, which involves recording all the physical evidence that is to be collected, the next step involves identifying the evidence. This step requires identifying and numbering the evidence, collecting it, and insuring it will be preserved in a condition suitable for subsequent lab analysis.

Identification Any item of physical evidence that will be collected must be identified. Generally, this identi- fication consists of a number and a brief description, as shown in the example in Figure 2.1.

Figure 2.1: Evidence log example

The length of an evidence log can vary from case to case, but maintaining an accurate list of evidence can save a lot of time later.

…..

46. T-shirt

47. Swabbing of blood-like substance

…..

Section 2.3Steps in Crime Scene Processing

Items that are to be collected are often marked with numbered placards. The number on the placard should correspond to the number used to identify that item. The number and descrip- tion are documented in the evidence log, which is a complete listing of physical items seized at the scene. This practice reduces paperwork and avoids the potential of making a clerical error if the evidence items are renumbered. It also makes it possible to relate evidence item numbers back to the original evidence in a photo or video from the scene.

Collection, Packaging, and Preservation Collecting and preserving evidence consist of using proper collection methods, using proper containers, and properly storing evidence in the lab or property storage area. It is always best to collect items intact; circumstances may force an investigator to take a sample of something, but it is best to avoid doing so. A pattern of blood on a floor must be sampled (by swabbing up some of it), or the floorboards must be collected, which may not always be possible or practi- cal. Agencies usually have guidelines that pertain to the collection process, but investigators must always use their best judgment. The goal is to collect the important evidence, or an appropriate sample of it, and to document in detail where it came from. Additionally, investi- gators must be sure to collect proper control and comparison specimens for any questioned evidence (hair, blood, handwritten documents, etc.) they are collecting.

When collecting a specimen, it is exceed- ingly important to select the right con- tainer. The container must completely contain the specimen. If portions of the specimen are left exposed, they are vul- nerable to being contaminated. In addi- tion, containers must be able to prevent the specimen from leaking out (especially if the item is small or a powder or liquid). Low-density polyethylene ziplock bags are good containers because they can hold a variety of samples and are transparent. This is important, because clear packag- ing allows the evidence to be identified

Think About It

Forensic evidence can be difficult to contain. Have you ever transported leftovers from a restaurant and had the contents leak out? Now imagine you knew you had to transport dozens of individual leftover packages, some with liquids, some with powders. What pre- cautions would you take up front?

without breaking tamper-proof evidence tape. However, ziplock bags are not used for biologi- cal evidence, because they are airtight.

Biological evidence (blood and body fluids, including swabs and stained items) needs to be allowed to dry. Therefore, it should not be packed in airtight containers; these increase the chance for bacterial growth, which will destroy the evidence. The exception is large samples of biological fluids, such as vials of blood. These are collected in special containers that are usually prepared with preservatives to prevent degradation.

Nonbiological liquids also have special storage container needs. Jars with screw-on caps, vials, and sealed paint cans are all common containers. It is important to remember that not all liquids can be put in the same containers. Solvents, acids, and bases all require specific types of containers. Using an inappropriate container can result in degraded seals and spilled or lost samples. In extreme cases, the sample may react with the container and become use- less for the purposes of the investigation.

Sharp objects like knives and broken glass need to be put into containers that are strong and can prevent them from ripping through. Containers also need to secure evidence so it doesn’t bounce around or get damaged in transport. Electronic devices and computer hard drives should be packed in nonconducting containers to prevent electrical damage.

Once a specimen has been properly contained, it should be labeled with the case number, date, time, location, and the name of the investigator who collected the item. The label should be affixed in a visible place and the container sealed with tape, unless it already has a tamper- proof seal. This process can be made more efficient by preprinting labels. High-volume agen- cies often use bar code systems that allow investigators to rapidly label and track samples via inventory-control programs. In the chapters to follow, we will discuss collection and packag- ing techniques appropriate to specific categories of evidence.

Once the evidence is collected, it is either stored or submitted for testing. If testing is needed, an item should be delivered to the crime lab as quickly as possible. Some evidence, like finger- prints on items, can degrade completely within a few days under normal storage conditions. Evidence that is left in the trunks of cars can experience temperature extremes that degrade the specimens even faster (Steele, 1994, 2015).

Evidence storage presents a challenge for laboratories and law enforcement agencies because cases take time to process and evidence needs space in which to be stored. Evidence such as frozen items that are submitted to a laboratory may be stored by the laboratory for an extended period. Some types of evidence, such as controlled substances or firearms, may remain in the secure possession of the laboratory until they are eventually destroyed. Most of the time, how- ever, the items are returned to the custody of law enforcement for secure storage.

If a case goes to trial, evidence is brought to court; once admitted into evidence, it becomes the property of the court. It must then be securely stored for some length of time. Procedures vary from jurisdiction to jurisdiction, and sometimes from case to case, regarding how long evidence needs to be stored after the case is completed. Sometimes a court order or other

Prathaan/iStock/Thinkstock Packaging and labeling evidence correctly is extremely important to preserving it and ensuring its admissibility in court.

Section 2.3Steps in Crime Scene Processing

without breaking tamper-proof evidence tape. However, ziplock bags are not used for biologi- cal evidence, because they are airtight.

Prathaan/iStock/Thinkstock Packaging and labeling evidence correctly is extremely important to preserving it and ensuring its admissibility in court.

Section 2.3Steps in Crime Scene Processing

authorization is required before evidence can be destroyed. Cases can be reopened decades after they have been adjudicated if new technology, such as improvements in DNA profiling, becomes available. This is usually called postconviction testing, and many states have statutes that govern its application. There are also old, unsolved cases with evidence that may be sub- jected to new forms of testing and comparisons that were not done at the time of the crime. These are usually called cold cases. Some police agencies have established cold case units that are specifically devoted to reexamining old, cold cases.

Submitting Evidence to the Laboratory Items that are submitted to a lab are recorded on a laboratory submission form, which includes the case number, date of incident, name(s) of person(s) involved, type of case, brief description of the case, and the contact information of the submitting agency and investiga- tors. There may be space for investigators to state what type of examination they are request- ing (such as “compare with DNA of John Jones and Mary Smith”). In complicated cases or cases in which the requested examination is not obvious, investigators should talk to the lab technician who will coordinate the handling of the case. If possible, it is good practice for the lab to retain the identifying numbers assigned by the investigators. Otherwise, every item will have more than one identifying number, and errors could be made along the way. Law enforce- ment agencies and the laboratory can agree in advance on a numbering and identifying scheme for evidence.

A given case may involve more than one submission of evidence to the laboratory. The lab will have a way to deal with this situation. Figure 2.2 shows an example of a laboratory evidence sheet. The submission form usually asks: Has evidence previously been submitted in this case? If the answer is yes, the new submission will be carried under the same case number, but with a new lab number. In a complex case, like a homicide, evidence may be submitted from the scene. Later, the medical examiner may provide evidence after a victim is autopsied. Still later, specimens from persons of interest or from vehicles may be submitted. Similar to an evidence log, the number of lab submission forms can vary depending on the case.

Think About It

Laboratories and law enforcement work together to identify, track, and store evidence. What problems do you think might arise if the police and crime lab used different identifi- cation and storage methods?

Section 2.3Steps in Crime Scene Processing

Figure 2.2: Illinois State Police lab submission form

This is an example of a form used to submit evidence to a laboratory.

Adapted from http://www.esd.whs.mil/Portals/54/Documents/DD/forms/dd/dd2922.pdf

FORENSIC LABORATORY EXAMINATION REQUEST

1. TO: 2. FROM:

3. RETURN EVIDENCE TO:

4. EXAM PRIORITY 5. LAB USE ONLY

a. LAB CASE #

b. METHOD OF RECEIPT

c. RECEIVED BY/DATE

6. SUBMITTING AGENCY CASE NUMBER 7. TYPE OF OFFENSE

8. PREVIOUS EVIDENCE SUBMITTED DATE: MAIL METHOD: LAB CASE #: SUSPECT(S):

9. SUSPECT(S) [Last, first and middle name(s)] 10. VICTIM(S) [Last, first and middle name(s)]

11. BRIEF DESCRIPTION (SYNOPSIS) OF CASE FACTS THAT MIGHT ASSIST THE LABORATORY IN EXAMINING OR EVALUATING THE EVIDENCE OR ADDITIONAL DOCUMENTATION ATTACHED (e.g., Summary of investigation, crime scene sketches/photographs, statements)

12. EVIDENCE SUBMITTED a. EXHIBIT b. DESCRIPTION OF EXHIBIT

ROUTINE EXPEDITE

Trial/Article 32/39A (*)

Subject in pre-trial confinement Subject pending PCS/

Separation/Reenlist (*) Other (Specify in Block 13)

*Date

Other (Specify):

Section 2.3Steps in Crime Scene Processing

Figure 2.2: Illinois State Police lab submission form (continued)

This is an example of a form used to submit evidence to a laboratory.

Adapted from http://www.esd.whs.mil/Portals/54/Documents/DD/forms/dd/dd2922.pdf

12. EVIDENCE SUBMITTED (Continued)

a. EXHIBIT b. DESCRIPTION OF EXHIBIT

13. EXAMINATION(S) REQUESTED (Briefly furnish any information or instructions that might assist the laboratory in examining the evidence)

14.a. INVESTIGATOR AND ALTERNATE POC (Typed or Printed) (Mandatory Information) b. TELEPHONE (Primary/Alt):

c. DSN (Primary/Alt):

d. Fax:

e. E-Mail:

15. I CERTIFY EVIDENCE HAS NOT BEEN SUBMITTED TO ANOTHER LABORATORY FOR THE SAME EXAMINATION

a. DATE b. TYPED/PRINTED NAME OF REQUESTOR d. TELEPHONE (Primary/Alt):

e. DSN (Primary/Alt): c. SIGNATURE

f. Fax:

g. E-Mail:

16. LAB USE ONLY

LAB CASE #

Section 2.3Steps in Crime Scene Processing

Chain of Custody Chain of custody encompasses the notion that an item of evidence can be traced from its sei- zure to its introduction as evidence in a courtroom. If the state cannot adequately account for who had care, custody, and control of an item between seizure and the courtroom, that item may be deemed inadmissible. When investigators seal an item at the scene, the lab examiner will take great care to not break the investigator’s seal. The package will be opened else- where—such as at the other end of the envelope or bag—and resealed following examination. The person who sealed the evidence will initial the tamper-proof tape or packaging. Ideally, the evidence item is opened only once—for laboratory examination—then resealed and not opened again unless the investigator or lab examiner is asked to do so in the courtroom.

The courts have generally been satisfied with “ordinary business records” to establish chain of custody. The state does not normally need to produce anyone who had access to the evi- dence along the way. The label, tag, bar code, or whatever device or strategy is being used to track and maintain the chain is very important, since evidence can exchange hands many times. An item of evidence might go from the scene, to the department property room, to the lab receiving unit, to the lab master storage vault, to an examiner’s bench (possibly more than once and possibly to more than one examiner), back to the lab master storage vault, back to the department property room, and finally to the court’s evidence storage room and to the courtroom.

The case of Connecticut v. Richard B. Crafts (1993) is interesting from a forensic standpoint because almost every common subspecialty was involved in examining the evidence. The case illustrates how a wide spectrum of circumstantial evidence must sometimes be assembled to resolve a case. As you read about the case, consider how the steps of crime scene processing factored into getting the evidence into court, and consider the evidence’s impact on the case.

Think About It

Should all evidence in every case be examined? How would you decide what is important to examine and what is not?

Case Illustration: Connecticut v. Richard B. Crafts In November 1986 a flight attendant named Helle Crafts hired Keith Mayo, a private inves- tigator, to find evidence that her husband, Richard B. Crafts, was having an extramarital affair, which she wanted to use in a divorce suit against him. Mayo had the evidence of the affair but had been unable to give it to Helle Crafts and be paid for his services, because Helle disappeared. After returning to JFK Airport on a flight from Europe, she rode home to Connecticut with a fellow flight attendant and was never seen again. Both her flight atten- dant friend and Mayo were concerned about her disappearance. Helle had told her friend that her husband was abusive and that if something ever happened to her, he should be looked at with suspicion.

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Section 2.3Steps in Crime Scene Processing

Case Illustration: Connecticut v. Richard B. Crafts (continued) Richard was a part-time Newtown, Connecticut, police officer. Perhaps because of this, the Newtown police were reluctant to make much of the fact that Helle was missing when they were told about it. Fortunately, Mayo was able to get the state’s attorney’s office involved, and they asked the Connecticut State Police to look into the matter. Richard told investiga- tors that Helle had said she was going to visit her mother in Europe, and her car was found in the employee parking area at the JFK Airport. However, there was no record of her on a flight to Europe.

The morning after Helle had returned home, Richard instructed the nanny to take their children to their grandparents’ home, saying he would join them later. Richard then went to a rental store and asked to rent a large diesel-powered wood chipper. He rented a U-Haul truck to tow the wood chipper. Richard owned a wood lot along the shores of Lake Zoar and said he was going out to his wood lot to cut wood. There was a major snowstorm that night, and a snowplow driver said he saw a truck pulling a wood chipper. He was not able to see the face of the driver but said the truck pulling the wood chipper was heading toward Richard’s wood lot. The snowplow driver said that there was no one else on the roads because of the storm.

State Police investigators were now suspicious of Richard and conducted an extensive search of the wood lot alongside Lake Zoar. As they searched for clues along the shoreline and in areas where Richard had been chipping wood, they picked up leaves, surface mate- rial, and debris and placed them into 50-gallon barrels filled with water, which floated off the leaves and low-density debris. The water was then poured through a fine-mesh sieve for evidence. Using this technique, investigators discovered

• a human tooth, • a human dental restoration, • hundreds of small pieces of human bone, • part of a finger with some fingerprint friction ridges, and • a human toenail that was painted with red nail polish.

State Police divers also looked in the lake for evidence and recovered a Stihl chain saw with about a half tank of fuel still in it.

This case required forensic odontologists (to examine the tooth and the restoration) and forensic anthropologists (to examine the bone). Additionally, a forensic pathologist (state medical examiner) provided an opinion about the cause and manner of death.

The minute pieces of bone, the chain saw, and other evidence were examined in a forensic laboratory. The chain of the chain saw contained blood, hairs, and fibers. Wood chippings from the Lake Zoar site as well as from the U-Haul rental truck were collected. Some bits of chippings and debris contained hair. The wood chipper was extensively examined, but it had been rented to someone else after Richard had rented it, and when State Police got to it, nothing probative was uncovered. The blade was also swapped out with every rental, and the one that was in the machine at the time of Richard’s rental was not available.

State Police believed Richard had murdered Helle and disposed of her body using the wood chipper. Police obtained a search warrant for the Crafts’ home. The wall-to-wall carpeting in the master bedroom was gone and was never found. Richard said he was in the process of replacing it. The mattress was gone too, but the box spring was still there and had blood spatter on it.

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Section 2.3Steps in Crime Scene Processing

Case Illustration: Connecticut v. Richard B. Crafts (continued) Without going into the investigative details, here is a summary of the basic case facts and the forensic evidence. What story can each piece of evidence tell?

• Tooth/restoration: Identified as having come from Helle Crafts. • Bone chips: Human; consistent with production by a high-speed wood chipper blade;

tool marks consistent with those on the wood chips; all originating from head, hands, or feet; blood group O (same as Helle).

• Wood chips: The tool marks from the wood chipper blade were consistent with one another, consistent with having been produced by a wood chipper blade, and consistent with the marks on the bone chips. This means that all marks could have been made by the same blade in the wood chipper.

• Chain saw: The chain saw had a serial number, but it was badly marred from being in the water. Using serial number restoration techniques, the serial number was restored. The chain saw was traced to a retailer in Connecticut, and the retailer had the credit card slip Richard used to purchase the saw. He paid nearly $645 for it. In addition, a questioned document examiner verified that the signature on the credit card slip belonged to Richard.

• Box spring bloodstains: Medium-velocity blood spatter. This means that there was force involved in their production. They are typically seen in blunt-force beatings on the head when the blunt-force object contacts the head when it is bloody. These were blood type O, the same as Helle. They were of relatively recent origin because one isoenzyme could be typed. It is not likely they were more than a year old, and probably not that old.

• Hairs: Human; morphologically consistent with one another; morphologically consistent with hairs from a hairbrush from Helle’s bathroom. The defense correctly pointed out that the hairbrush could not truly be used to identify Helle.

• Fibers: The fibers found in the chain saw blade were consistent with fibers from a night- gown Helle owned and was known to have worn but which was not recovered.

• Partial finger: The friction ridge skin on the partial finger was consistent with Helle’s known fingerprint, but not enough detail overlapped between the two to make a posi- tive identification.

• Toenail and polish: Consistent by instrumental methods of analysis with a bottle of nail polish recovered from Helle’s bathroom. Nail polish cannot be individualized. It was not possible to say that the polish on the toenail came from that bottle, only that it could have.

Crafts case was an extreme example of a highly circumstantial case. There is a lot of cir- cumstantial evidence that implicates Richard in Helle’s death and more convincingly in the disposal of her remains. Most of it by itself is not very strong. The question for the jury, then, is whether many pieces of circumstantial evidence that point to the same conclusion constitutes proof beyond a reasonable doubt. This death investigation case began in late 1986 and continued into 1988, but the first trial ended in a mistrial. The state retried the defendant, Richard Crafts, in 1989, and he was convicted.

Reflect On It Based on this case, would you change your previous opinion of whether all evidence should be examined?

Section 2.4Crime Scene Analysis and Reconstruction

2.4 Crime Scene Analysis and Reconstruction There is a difference between crime scene processing and analysis. Processing consists of evaluating and identifying evidence; documenting, collecting, and packaging evidence; and submitting relevant items to a forensic lab. Analysis, on the other hand, is part of an effort to reconstruct events. The scene and scene patterns are important in reconstructions, but all other medical/lab findings and investigative information must be considered.

It is never possible to fully reconstruct a crime based on the record or analysis of physical evidence. However, some reconstruction attempts are broader than others. An investigator might, for example, interpret a blood pattern left at a scene. This information may contribute to understanding the case, but it is limited to the single event that caused the pattern. Inves- tigators might also try to reconstruct the movements of people in a scene to try to create a theoretical timeline. This could be based on an observation such as a footprint on the cover of a magazine that was found under an overturned table. These timelines are often critical to generating a complete description of the crime, but it is important to remember that different events can sometimes result in identical sets of evidence.

Any reconstruction is a hypothesis, or theory, about what may have happened based on the available evidence. As more data comes in, the theory must be modified. The lab analysis of the items submitted from the scene is critical to the reconstruction. Matching (or failing to match) bloodstains or fingerprints with people, or bullets or cartridge cases with guns—as well as establishing the meaning of various scene patterns—is essential. In death cases, the medical examiner’s report is another critical item. The cause and manner of death must be established. The decedent must be positively identified, wounds described, bullets recovered, sexual assault evidence collected, and so on. Sometimes other specialists must be brought into a case, and their findings become important to the total picture. If there is insect activity on a corpse, for example, a forensic entomologist can help establish the time that has passed since death. If there are bite marks on a body or on food items at a scene, a forensic odontolo- gist can compare those marks with the known teeth of persons of interest.

Scenes may present any number of patterns that can be useful in reconstruction. These include blood patterns; glass fractures; tracks and trails; modus operandi; tire skid marks; clothing, article, or object positions; gunshot residue; bullet or projectile trajectories; and fire burn. Not all of these patterns will be included at every scene, but they can be helpful when reconstructing events.

Glass fracture patterns can reveal information such as which side of the glass was struck, the order of shots fired, and force and angle of impact. Tracks and trails may consist of footprints, footwear impressions, blood droplets, or drag marks and can show the movements of people at a scene. A modus operandi (MO) is a habitual pattern that a criminal follows. Investigators have for years used MO patterns to link cases. A newer and more sophisticated application of this type of analysis is profiling. Law enforcement personnel with psychology backgrounds and special training in criminal profiling can use information from a scene and its analysis to paint a profile of the offender. The profile is never sufficient to identify a person, but it may narrow down the list of potential suspects. The profile is based on studying past crimes for which a perpetrator has been apprehended. Often, certain offenders will have characteristics in common, such as age, relationships with other people, or type of job, which can help the profiler. Skid marks from tires are useful in reconstructing traffic accidents, as they can help

Section 2.5Advances in Forensic Technologies

determine how fast a vehicle was moving when the brakes were applied. Patterns of cloth- ing, furniture, or other articles can help determine what happened and set some context. The objective is to look for the unusual—things that would not be expected in the circumstances. Things that are upset or out of place might indicate a ransacking or a struggle or provide hints about a motive. It is important to figure out what type of case the scene represents. Is it an intentional murder, a robbery, a burglary, a sexual assault, or an aggravated assault? Does it look like the offense was committed by a stranger, someone the victim knew, or someone who lives on the premises?

2.5 Advances in Forensic Technologies As casework demands have increased and budgets have not, labs have sought ways to improve their efficiency and productivity. Databases, laboratory information management systems (LIMS), and robotics are important tools that help satisfy this need. Databases help save time in an investigation by pooling data from multiple jurisdictions. While there are many databases available, three of the most significant for law enforcement are Automated Fin- gerprint Identification Systems (AFIS), Combined DNA Indexing System (CODIS), and National Integrated Ballistic Information Network (NIBIN).

AFIS holds fingerprint images from people who were arrested or who have applied for a gun license, security clearance, trusted traveler card, or to drive a school bus, and those from unsolved cases. We will discuss AFIS more in Chapter 8, but it is a database that is easily searched to locate matches. Similarly, CODIS holds DNA profiles of convicted felons and arrestees, as well as missing person profiles and profiles from cases in which the DNA deposi- tor has not yet been identified. Any new profile can be CODIS-searched for matches. CODIS will be described and discussed more fully in Chapter 11.

NIBIN is an image database for bullets and cartridge cases. NIBIN is the only automated inter- state ballistic imaging network in operation in the United States, and it is available in most of the major population centers. This program allows users to match images of bullets and car- tridges recovered at a crime scene with those loaded into the database from known weapons or other crimes. Software can match the bullets and cartridge cases if they were fired from the same weapon. NIBIN will come up again in Chapter 9.

Most large labs run some form of LIMS. A fully operational LIMS tracks every item of evi- dence that passes through the lab, records every transfer of that evidence from a vault to a bench and back, captures analytical results such as spectra, and contains all notes on exam- ined items, in addition to the final report that is sent out. These systems are fairly large and

Think About It

Suppose you are an investigator with a large agency and you get a call to look into a report of a dead body off the side of a busy interstate highway. Arriving at the location, you find that there is indeed a body. What are your next steps? Why could this case be difficult to solve?

Section 2.5Advances in Forensic Technologies

expensive, server based, and require reliable backup. However, once implemented, they can save time and paperwork.

Speed and efficiency can also be improved by the use of laboratory robots. Robots include any machine that can process multiple samples on its own without human intervention, beyond loading and unloading. These machines are ideal when a method is repetitive and requires no judgment or interpretation. Robots are generally robust, reliable, and accurate. Their associ- ated software keeps detailed records of their actions. Typical tasks may involve transferring samples between containers, dispensing chemicals for a reaction, moving reaction vessels or tubes along a line, and similar tasks. Most standard drug identification, forensic toxicology, and DNA sequencing can be performed by robots, leaving human laboratory personnel free to perform other work.

Less commonly, robots can be integrated with optical recognition software to perform time- consuming microscopic examinations like searching a vaginal swab smear for sperm cells. Using fluorescent or staining techniques on the slide, a microscope equipped with appropri- ate robotics can manipulate the slide in a systematic manner while a detector searches for a signal associated with the sperm cell. The robot keeps track of the spatial coordinates where it found the signal, making it easy for a human examiner to confirm the presence of cells in a short amount of time.

Forensic science also relies on analytical methods that come from other industries and areas. Consider the methods developed for product and materials failures, acoustic analysis, and polygraph tests. Product and materials failure experts are usually engineers or production scientists, and product and materials failure cases are almost always civil cases that involve monetary damages. For example, automobile manufacturers are regularly sued over alleged defects in a car’s design or manufacture that are said to have caused accidents. Like criminal cases, these cases are built on reconstructions from available evidence. Sometimes, technol- ogy developed for use in these cases can go on to impact forensic scientists in criminal inves- tigations. For example, security inks used to thwart and track counterfeiters began as a batch coding system for ink companies to prove that product failures encountered by their custom- ers were related to old material and were not poorly made batches.

Acoustic analysis, which involves the instrumental analysis of sound waves using a wavelength spectrum, has its roots in military techniques for identifying sub- marines. There are many devices for doing this type of work, and much of the avail- able software runs on standard personal computers. Using a voice spectrograph, also called a voiceprint, graphs of sounds that show intensity and variation by fre- quency are used to compare unknown voices or sounds to known ones, with the goal of being able to reliably identify or exclude questioned voices or sounds. The expert community disagrees over the accuracy of this method, but many courts have admitted this type of evidence.

SVproduction/iStock/Thinkstock Acoustic analysis involves the comparison of a known sound against an unknown sound.

Conclusion

Finally, there is the polygraph, sometimes known as a lie detector, which has been around for decades. With an occasional exception, polygraph tests have not been admissible as evidence in courts, due to their unreliability as a truth or deception detector. You may recall that the first legal case involving the admissibility of scientific/technical evidence into court, Frye v. United States, was a polygraph case (Chapter 1.6). Polygraph rests on the idea that measurable physiological features, mainly sweating, heart rate, and respiration rate, will be affected if a person is knowingly untruthful. Although polygraph examiners can detect signs of untruth- fulness in many people, there is the occasional person who can “beat” the polygraph. In addi- tion, if individuals think they are being truthful even when they aren’t, the polygraph may not detect the lie. Polygraph is widely used in preemployment screening and for national security purposes. However, these applications do not involve a polygraph record being admitted into evidence in courts.

The takeaway from this discussion should be that forensic scientists and crime scene investi- gators need to stay current with other fields and disciplines even if they do not seem directly related to criminal investigations. Technological advances in other fields can have a signifi- cant impact on law enforcement.

Conclusion This chapter explained crime scene investigation, which involves both crime scene process- ing and analysis. Crime scenes themselves should all be approached as unique events with special needs, safety, and security concerns. Even though each case is unique, there are com- mon steps that need to be followed when processing a crime scene to avoid mishandling or illegally seizing evidence. Evidence that is not treated correctly will likely not be usable or admissible in subsequent judicial proceedings.

The reconstruction aspect of crime scene analysis provides hypothetical theories about the evidence encountered. These theories help direct the investigation and indicate what hap- pened. Remember that as more evidence is evaluated and understood, the reconstruction and subsequent hypothesis are subject to change. The methods and procedures used in crime scene analysis evolve over time. Computerized systems and databases can streamline rou- tine analysis and improve efficiencies. Techniques imported from other industries can also positively impact crime scene investigations. The chapters that follow will discuss specific categories of evidence and how these are collected, preserved, and analyzed in a laboratory.

Key Ideas

• Although there are common steps that should be followed in crime scene investiga- tions, every crime scene should be treated as a unique entity with specific needs.

• Crime scene processing involves recognizing, searching for, documenting, identify- ing, collecting, and preserving evidence and submitting it to the laboratory.

• Crime scene analysis is reconstruction and involves synthesizing all scene infor- mation, lab findings, medical examiner findings (in death cases), and investigative information.

• Reconstructions are theories based on the available evidence and information. They are always imperfect and not “proof” of what actually happened.

Conclusion

• Each step involved in processing a crime scene is important, as is the order in which the steps are done. The methods employed in crime scene investigation need to adhere to established quality procedures that meet industry standards.

• Scene security and chain of custody are key to recovered evidence being admissible in court and useful to solving the case and prosecuting offenders.

• All types of documentation are important. They detail different kinds of information and are required to fully record a crime scene.

• Technologies and investigative aids can be important in training for and practicing forensic science.

Critical-Thinking Questions

1. There is a call regarding a burglary and an assault at a residence. You arrive at the home and notice it is in a rural area surrounded by woods. What steps would you take upon arriving? How would you properly secure the crime scene?

2. You respond to a crime scene in a private residence and find that a homicide has been committed. The immediate situation is handled, the medical examiner comes and takes away the deceased’s body, and you and your team want to start a detailed search. An owner of the property is there, however, and says he wants you to leave immediately. You need to search the house. What options do you legally have at this point?

3. At a bloody scene, you find what look like trails of blood throughout a private resi- dence. These look like important patterns for the case. What is the first thing you should do to preserve the evidence? How do you think the blood trails could help reconstruct the crime scene?

4. You are working a crime scene, and one of your colleagues who has just returned from a training class shares with you a way to collect your evidence more efficiently than what is described in the formal SOP. Should you use the new method or follow the SOP? Why?

5. In what type of case do you think voice spectrograph technology might be useful to investigators?

Key Terms acoustic analysis The instrumental analy- sis of sound waves using a wavelength spectrum.

Automated Fingerprint Identification System (AFIS) A computer system that uses biometric identification derived from digital images to store, analyze, and com- pare fingerprints.

chain of custody Using documentation to track where evidence has been and identify who has been in control of it at every point from the scene to the courtroom.

Combined DNA Indexing System (CODIS) A set of large computer-based database files containing DNA profiles, enabling input, storage, and searching.

computer-aided drafting (CAD) sys- tem Software used to produce three- dimensional images (not to be confused with computer-aided dispatch systems used in law enforcement, which are also called CAD systems).

corrective action A report filed within a quality control system when an error has occurred and needs to be investigated to determine the proper response.

Conclusion

crime scene analysis Using the informa- tion present at a crime scene, the inves- tigative information developed, and the results of analyses of all the evidence from the crime scene to form a reconstruction hypothesis.

crime scene processing The process of searching for, recognizing, documenting, collecting, and submitting evidence from a crime scene.

criminal profiling The construction of a perpetrator’s personality profile and description based on psychology and research on past offenders.

cross-projection sketch A two-dimen- sional sketch that represents three real- world dimensions by “flattening out” a room’s walls and ceiling, much like cutting the edges of a rectangular box so that its sides and top can be laid flat.

exigent circumstances Circumstances (such as a person being in danger or a suspect trying to escape) that would lead a reasonable person to decide that it is neces- sary to enter a protected space or take other immediate action without a warrant.

improvement In the context of a quality control system, an improvement is a sub- mitted suggested alteration to the SOPs intended to improve the process and/or output.

International Organization for Standard- ization (ISO) A standard-setting body that includes representatives from various national standards organizations.

Laboratory Information Management System (LIMS) An integrated software package for tracking items, test results, and chain of custody for evidence into, through, and out of a laboratory.

metamerism A phenomenon whereby an object appears to be a different color under different lighting.

modus operandi (MO) The habits (when committing an offense) of a repeat offender.

National Integrated Ballistic Informa- tion Network (NIBIN) A large database of images of bullets and cartridge cases.

preventative action A report filed within a quality control system when there is a situ- ation that might lead to an error and needs to be investigated to determine the proper response.

rough (preliminary) sketch A sketch made at the scene that is not drawn to scale and may contain extraneous items and show measurements.

scale Any measuring device or indicator relating distance on a sketch to real-world distance.

smooth (finished) sketch A sketch made from a rough sketch that is drawn to scale, does not show any measurements, and usu- ally omits extraneous items.

voice spectrograph An instrument that converts a person’s voice pattern into an electronic graphic format. Voice spectro- graphs can be compared to see whether they represent the same speaker.

Web Resources Crime Scene Investigation A Guide for Law Enforcement: https://www.nist.gov/sites/default/files/documents/forensics/Crime-Scene -Investigation.pdf

Conclusion

Crime Scene Investigator Network: Resources for learning about crime scene investigation: http://www.crime-scene-investigator.net/index.html

FBI Cyber Crime website: http://www.fbi.gov/about-us/investigate/cyber

Information on digital evidence investigations from the Scientific Working Group on Digital Evidence: http://www.swgde.org

ISO quality manual: https://asq.org/quality-resources/iso-9001-quality-manual

Landscape Study on 3D Crime Scene Scanning Devices (Forensic Technology Center of Excellence): http://www.rieglusa.com/pdf/landscape-study-on-3d-crime-scene-scanning-devices.pdf

A Simplified Guide to Crime Scene Photography (National Forensic Science Technology Center): http://www.forensicsciencesimplified.org/photo/Photography.pdf

National Institute of Justice Technical Work Group guides: https://www.nij.gov/topics/law-enforcement/investigations/crime-scene/guides/pages /twgs.aspx

National Institute of Justice’s guide to crime scene processing for law enforcement officers: http://www.ncjrs.gov/pdffiles1/nij/178280.pdf

U.S. Department of Justice Internet resources on computer crime and intellectual property: http://www.justice.gov/criminal/cybercrime