As technology and scientific methodology evolve, concerns about good or valid science or flawed science also evolve. New methodologies and scientific processes must be carefully ev

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.

37

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.

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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

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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?

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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?

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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.

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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?

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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.

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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.

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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?

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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?

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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 responsib

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