S E C T I O N I I The Crime Scene Section Overview In the previous section, we established the foundations and fundamentals of forensic science as a discipline. We learned a bit about its history and how science operates within the legal system. We discussed evidence from many perspectives and now we begin our exploration of where evidence comes from. The topics of crime scenes and death investigation are inextricably linked, and we will delve more deeply into that subject in the section to follow. However, it is worth remembering that not all crime scenes involve a death. Crime scenes can be as simple (relatively speaking) as a burglary, as dangerous as a clandestine drug laboratory, or as complex as a multiple murder that takes place in several different locations. Although each scene is unique, the principles that underlie their inves- tigation are consistent. In this section, we will focus on these common elements. Not all physical evidence arises from crime scenes, but all crime scenes create physical evidence. From nanogram quantities of DNA to artificial intelligence databases capable of identifying latent fingerprints and biological fluids, forensic science and the analysis of very minute quantities of physical evidence have advanced and improved. Crime scene investigation is the starting point for
Transcript
S E C T I O N I I
The Crime Scene
Section Overview
In the previous section, we established the foundations and fundamentals of forensic science as a discipline. We learned a bit about its history and how science operates within the legal system. We discussed evidence from many perspectives and now we begin our exploration of where evidence comes from. The topics of crime scenes and death investigation are inextricably linked, and we will delve more deeply into that subject in the section to follow. However, it is worth remembering that not all crime scenes involve a death. Crime scenes can be as simple (relatively speaking) as a burglary, as dangerous as a clandestine drug laboratory, or as complex as a multiple murder that takes place in several different locations. Although each scene is unique, the principles that underlie their inves-tigation are consistent. In this section, we will focus on these common elements.
Not all physical evidence arises from crime scenes, but all crime scenes create physical evidence. From nanogram quantities of DNA to artificial intelligence databases capable of identifying latent fingerprints and biological fluids, forensic science and the analysis of very minute quantities of physical evidence have advanced and improved. Crime scene investigation is the starting point for
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the successful use of physical evidence by the forensic laboratory and the crimi-nal investigator. Successful, high-quality crime scene investigation is a simple but methodical process. It allows the investigators to adapt to the unique characteris-tics of each scene, yet the overall process follows a set of principles and procedures that adhere to guidelines ensuring that all of the physical evidence is discovered and investigated. The basic crime scene procedures are physical evidence recogni-tion, documentation, proper evidence collection, packaging, and preservation. Once evidence is delivered to the laboratory and testing is completed, scene reconstruc-tion can take place. Every crime scene is unique, and with experience the crime scene investigator will be able to use this logical and systematic approach to inves-tigate even the most challenging scene to a successful conclusion.
This section of the text will present the many aspects of crime scene analysis and processing starting with the fundamentals of crime scenes and their documenta-tion. This will include a discussion of forensic photography, which has evolved at the speed of digital imaging. The second chapter in this section will explore bloodstain patterns, a critical type (but certainly not the only type) of evidence in many violent crimes. Bloodstain patterns can be the key evidence that allows investigators to understand the sequence of events that occurred and to sort out contradictory ver-sions of what happened.
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41
3Crime Scene Investigation
Chapter Overview
Any place can become a crime scene. A crime scene may be in a car, in a home, or even under water. Each crime scene is unique because the chain of events that create it is unique, but there are some unifying themes that dictate how a crime scene is studied and processed. In this chapter, we will study crime scenes in general and what information and evidence they can yield. Once a crime scene is created, it immediately begins to change and decay. For this reason, we will emphasize methods of documenting a crime scene to preserve the information for later study.
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42 Forensic Science: An Introduction to Scientific and Investigative Techniques
Chapter 3
Crime Scene Investigation*
Marilyn T. Miller and Patrick Jones
3.1 Defining the Crime Scene
The only thing consistent about crime scenes is their variety. Because of the diver-sity of possible scenes there are many ways to define or classify crime scenes. First, crime scenes can be classified according to the location of the original criminal activity. This classification of the crime scene labels the site of the original or first criminal activity as the primary crime scene and any subsequent crime scenes as secondary crime scenes. This classification does not assign any priority or impor-tance to the scene but is simply a designation of sequence of locations. For example, if a person is killed in an apartment and the body is then moved in a car trunk to a remote dump site, the apartment is the primary scene while the car and the dump site are secondary crime scenes.
* This chapter is based in part on Chapter 10, “Crime Scene Investigation,” by Marilyn T. Miller, and Chapter 11, “Forensic Digital Photo Imaging,” by Patrick Jones, as published in the third edition of this text.
Chapter Outline
3.1 Defining the Crime Scene .........................................................................423.2 Uses for and Information from Physical Evidence in Crime Investigations .............................................................................453.3 General Crime Scene Procedures .............................................................45
3.3.1 Scene Management .......................................................................453.3.2 First Responding Officer ...............................................................463.3.3 Crime Scene Survey ......................................................................46
3.4 Crime Scene Documentation and Forensic Photography ........................473.4.1 Digital Imaging and Photography ...............................................473.4.2 Forensic Mapping ..........................................................................493.4.3 Notes ..............................................................................................503.4.4 Video Recording Crime Scene ......................................................513.4.5 Sketching the Crime Scene ...........................................................513.4.6 Crime Scene Searches ...................................................................53
3.5 Collection and Preservation of Physical Evidence ...................................603.6 Crime Scene Reconstruction .....................................................................62
3.7 Review Material ........................................................................................653.7.1 Key Terms and Concepts ...............................................................653.7.2 Review Questions ..........................................................................65
3.8 References and Further Reading ..............................................................653.8.1 Books..............................................................................................653.8.2 Journal Articles ............................................................................66
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43Crime Scene Investigation
A second classification of crime scenes is based on the size of the crime scene. Using this classification, a single macroscopic crime scene such as a house may actually be composed of many smaller or microscopic crime scenes. For example, a gunshot victim’s body dumped in a field represents the following crime scenes within the overall crime scene of the field: the body, the body’s wounds, and the ground around the body. The microscopic classification of the scene is more focused on the specific types of physical evidence found in the macroscopic crime scenes. Using the previous example, the microscopic crime scenes are the trace evidence on the body, the gunshot residue around the wound, and the tire tread marks in the ground next to the body. Other descriptions of the crime scene include those based on the type of crime committed (e.g., homicide, robbery, sexual assault), the crime scene condition, the physical location of the crime scene (e.g., indoors, outdoors, vehicle), and the type of criminal behavior associated with the scene. We will learn much more about how criminal behavior and motivation are reflected in a crime scene in Chapter 20.
At the scene, investigators may need to update their assessments as their work progresses. No single definition will work adequately for every scene, and, indeed, there is no need for this as long as the scene is, at the final measure, correctly defined and described. Similarly, the spatial boundaries of scenes may change as the process-ing continues and investigators take care to avoid establishing immoveable boundar-ies to any crime scene. The crime expands and changes as the evidence dictates.
3.2 Uses for and Information from Physical Evidence in Criminal Investigations
The objectives of any crime scene investigation are to recognize, preserve, collect, and interpret all of the relevant physical evidence at a crime scene with the goal of reconstructing the events that generated this evidence. Often, it is difficult to determine what is pertinent evidence and what is extraneous; this is where the skill and experience of crime scene investigators are invaluable. (For a discus-sion of career preparation for crime scene investigators, see Sidebar 3.1.) This is always a team effort in which the forensic scientist and crime scene investigators play a role. A forensic laboratory examines the physical evidence to provide the investigator with information to help solve cases. The integration of the crime scene investigation with forensic testing of the physical evidence forms the basis of
SIDEBAR 3.1. CAREER PREPARATION AND EXPECTATIONS
Increasingly, the entry-level requirement for a crime scene processing job is a science degree from a college or university. Ideally, that degree includes edu-cation and laboratory training in crime scene processing and related forensic skills. Crime scene analysts can work as part of law enforcement as officers or as analysts in a laboratory. The former is becoming more common, and in these cases crime scene analysts typically do not do a significant amount of labora-tory work. Their primary responsibility is crime scene processing and evidence collection. The primary professional organization for crime scene analysis is the International Associate for Identification (http://www.theiai.org/), which certifies crime scene analysts.
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44 Forensic Science: An Introduction to Scientific and Investigative Techniques
scientific crime scene investigation (Figure 3.1). The following are examples of the types of information that can be obtained from forensic testing and examination of physical evidence in a criminal investigation:
t� Linkage of persons, scenes, or objects—This is the principle behind all crime scene investigations. Recall our earlier discussion of Locard’s exchange prin-ciple, which states that whenever two objects come into contact there will be a mutual exchange of matter between them. Linking suspects to victims is the most important and common type of linkage made by physical evi-dence in criminal investigations. For example, a victim of a shooting may not remember exactly where the crime occurred, but evidence recovered from the victim’s shoes or clothing could be useful in establishing the location.
t� Investigative leads—Physical evidence can provide direct information to an investigator; however, not all physical evidence at the crime scene will be directly linked to a suspect. Frequently, the physical evidence will provide indirect information or investigative leads to the investigator. This is an important and significant use of physical evidence in any criminal investiga-tion. Not every crime scene has individualizing physical evidence, such as fingerprints, but every crime scene will have physical evidence that assists the investigator with information, such as a footwear impression’s manufac-turer or the size and type of shoe worn by the suspect.
t� Information on the corpus delicti—Determination of the essential facts of an investigation involves the physical evidence itself, patterns of the evi-dence, and laboratory examinations of the evidence. The red-brown stains in a kitchen may be significant to an investigation but may be more relevant if those stains are bloodstains with DNA matching a victim.
t� Information on the modus operandi—Criminals repeat behavior, and this par-ticular behavior represents their signature or preferred method of operation. Burglars will frequently gain entry into scenes using the same technique each time, or bombers will repeatedly use the same type of ignition device. The physical evidence they leave behind, once found at the scene, can be used to identify them. This topic will be discussed at length in Chapter 20.
t� Proving or disproving witness statements—Credibility is an important issue with witnesses, victims, and suspects. The presence or absence of certain types of physical evidence will be useful in determining the accuracy of their statements. Crime scene patterns or patterned physical evidence (e.g., blood-stain patterns, fingerprints, gunshot residue) are especially well suited for determination of credibility.
t� Identification of the suspect(s)—Forensic examination is a process of recogni-tion, identification, individualization, and reconstruction. Identification of a suspect may be accomplished by matching a recovered latent fingerprint to a fingerprint in a database or from matching a DNA profile of a tiny bloodstain to a profile in a database. We will discuss fingerprints in Chapter 13 and DNA typing in Chapter 9.
Victim Suspect
Physical evidence
Object Crime scene
Figure 3.1 Diagram of crime scene interactions.
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45Crime Scene Investigation
t� Identification of unknown substances—As above, the identification of unknown substances is a common use of physical evidence. Identification of white powders as controlled substances or poisons such as anthrax are examples.
t� Reconstruction of a crime—This is the final step in the forensic examination process. The crime scene investigator is frequently more interested in how a crime occurred than in identifying or individualizing the evidence at the scene. At this point, the “how” of a crime scene is more important than the “who” of the crime.
3.3 General Crime Scene Procedures
3.3.1 Scene Management
The four distinctive but interrelated components of crime scene management are (1) information management, (2) manpower management, (3) technology man-agement, and (4) logistics management. Deficiencies, negligence, or overemphasis of any one of these components will imperil the overall crime scene investigation. These components are all based on the fundamental need to maintain good and ongoing communication among all personnel throughout the entire investigation process. The components of crime scene management and the need for continual communication have resulted in some choices for appropriate crime scene inves-tigation models. Each model has its advantages and disadvantages based on the allocation of personnel and resources, training and expertise, crime rates, types of crimes, jurisdictional issues, and the support services available. Details are pro-vided in Table 3.1
TABLE 3.1Crime Scene Investigation Models
Model Type Description Advantages Disadvantages
Traditional Use of patrol officers and detectives as crime scene technicians
Useful if resources and demand are relatively low
Minimal experience and time commitment conflicts with regular duties
Crime scene technicians
Specially trained, full-time civilian personnel
Continuity, specialization, scientific/technical training
Minimal investigative experience, lack of a global view of investigation
Depletion of investigative resources due to transfers out of unit, only major cases handled
Lab crime scene scientist
Laboratory scientists Superior technical and scientific skills, knowledge of current methods
No investigative experience, depletion of laboratory resources
Collaborative team
Use of police officers, technicians, lab personnel, medical examiners, and prosecuting authorities
Advanced scientific, technical, and investigative resources; shared responsibilities
Extensive resources and comprehensive procedures required, with continual communication
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46 Forensic Science: An Introduction to Scientific and Investigative Techniques
3.3.2 First Responding Officer
The first responding officers to a crime scene are usually police officers, fire department personnel, or emergency medical personnel. These first responders are the only people to view the crime scene in its most original or pristine condition. Their actions at the crime scene will form the basis for successful or unsuccess-ful resolution of the investigation. They must perform their duties, but they should always keep in mind that they are part of the beginning effort to link victims to suspects to crime scenes. They must never destroy that link. It is imperative that they gain experience and receive continual training or education.
Ideally, the first responders will maintain an open and objective mind when approaching the crime scene. Upon arrival at the scene, safety is a primary concern for themselves and the victim. Once the scene or the victim is safe then the first responders must begin to thoroughly document their observations and actions at the scene. As soon as possible, the first responders should initiate crime scene security measures. The duties of first responders include the following:
t� Assist the victim and prevent any changes to the victim.t� Search for and arrest the suspect if that person is still on the scene.t� Detain any witnesses. If possible, keep the witnesses separated to preserve
their objectivity. Do not take them back to the scene if at all possible.t� Protect and secure the crime scene. Begin taking crime scene security mea-
sures by using barrier tape, official vehicles, or other means, as required. Establish a crime scene security log to record any persons who enter or exit the crime scene and limit access to those who truly need it. This helps pre-vent contamination of the scene with materials brought in after the crime has occurred.
t� Document all movements, alterations, or changes made to the crime scene and pass this information to crime scene investigators.
3.3.3 Crime Scene Survey
Once the crime scene investigator has arrived at the crime scene and scene security has been evaluated, the preliminary scene survey, or walk-through, is performed. The crime scene investigator and the first responder will usually do the scene sur-vey together. The lead investigator or detective, if available, can also benefit from the scene survey. Often, digital images are collected. The survey is the first exami-nation or orientation of the crime scene by the crime scene investigator, and the fol-lowing guidelines should be followed:
t� Use the walk-through as a mental beginning for a reconstruction theory that can and should be changed as the scene investigation progresses.
t� Note any transient (temporary) or conditional (the result of an action) evi-dence that might be present and requires immediate protection or processing.
t� Be aware of the weather conditions, and take precautions if adverse weather is anticipated.
t� Note any points of entry or exit and paths of travel within the crime scene that may require additional protection. Be aware of any alterations or con-tamination of these areas by first responder personnel.
