The Green River Killer, Exercises of Law

Download The Green River Killer and more Exercises Law in PDF only on Docsity! The Green River Killer This case takes its name from the Green River, which flows through Washington State and empties into Puget Sound in Seattle. Within a six-month span in 1982, the bodies of five females were discovered in or near the river. Most of the victims were known prostitutes who were strangled and apparently raped. As police focused their attention on an area known as Sea-Tac Strip, a haven for prostitutes, girls mysteriously disappeared with increasing frequency. By the end of 1986, the body count in the Seattle region rose to forty; all were believed to have been murdered by the Green River Killer. As the investigation pressed on into 1987, the police renewed their interest in one suspect, Gary Ridgway, a local truck painter. Ridgway had been known to frequent the Sea-Tac Strip. Interestingly, in 1984 Ridgway actually had passed a lie detector test regarding the Green River killings. Now with a search warrant in hand, police searched Ridgway’s residence and also obtained hair and saliva samples from him. Again, insufficient evidence caused Ridgway to be released from custody. With the exception of one killing in 1998, the murder spree stopped in 1990, and the case remained dormant for nearly ten years. However, the advent of DNA testing brought renewed vigor to the investigation. In 2001, semen samples collected from three early victims of the Green River Killer were compared to saliva that had been collected from Ridgway in 1987. The DNA profiles matched and the police had their man. An added forensic link to Ridgway was made by the location of minute amounts of spray paint on the clothing of six victims that compared to paints collected from Ridgway’s workplace. Ridgway ultimately avoided the death penalty by confessing to the murders of forty-eight women. Key Terms class characteristics comparison identification individual characteristics product rule reconstruction identification The process of determining a substance’s physical or chemical identity. 80 CHAPTER 3 Key Points • Biological crime-scene evidence includes blood, saliva, semen, DNA, hair, organs, and physiological fluids. • Impression crime-scene evidence includes tire markings, shoe prints, depressions in soft soils, all other forms of tracks, glove and other fab- ric impressions, tool marks, and bite marks. • Manufactured items considered common items of crime-scene evi- dence include firearms, ammunition, fibers, paint, glass, petroleum products, plastic bags, rubber, polymers, and vehicle headlights. The Examination of Physical Evidence Physical evidence is usually examined by a forensic scientist for identifica- tion or comparison. Identification Identification has as its purpose the determination of the physical or chemical identity of a substance with as near absolute certainty as existing analytical techniques will permit. For example, the crime laboratory is fre- quently asked to identify the chemical composition of preparations that may contain illicit drugs such as heroin, cocaine, or barbiturates. It may be asked to identify gasoline in residues recovered from the debris of a fire, or it may have to identify the nature of explosive residues—for example, dynamite or TNT. Also, the identification of blood, semen, hair, or wood would, as a matter of routine, include a determination for species origin. For example, did a bloodstain originate from a human as opposed to a dog or cat? Each of these requests requires the analysis and ultimate identifi- cation of a specific physical or chemical substance to the exclusion of all other possible substances. The process of identification first requires the adoption of testing pro- cedures that give characteristic results for specific standard materials. Once these test results have been established, they may be permanently recorded and used repeatedly to prove the identity of suspect materials. For example, to ascertain that a particular suspect powder is heroin, the test results on the powder must be identical to those that have been previ- ously obtained from a known heroin sample. Second, identification requires that the number and type of tests needed to identify a substance be sufficient to exclude all other substances. This means that the examiner must devise a specific analytical scheme that will eliminate all but one substance from consideration. Hence, if the examiner concludes that a white powder contains heroin, the test results must have been comprehensive enough to have excluded all other drugs—or, for that matter, all other substances—from consideration. Simple rules cannot be devised for defining what constitutes a thor- ough and foolproof analytical scheme. Each type of evidence obviously re- quires different tests, and each test has a different degree of specificity. Thus, one substance could conceivably be identified by one test, whereas another may require the combination of five or six different tests to arrive comparison The process of ascertaining whether two or more objects have a common origin. Physical Evidence 81 FIGURE 3–1 Side-by-side comparison of hairs. Courtesy Chris Palenik, Microtrace, Elgin, IL., www.microtracescientific.com at an identification. In a science in which the practitioner has little or no control over the quality and quantity of the specimens received, a standard series of tests cannot encompass all possible problems and pitfalls. So the forensic scientist must determine at what point the analysis can be con- cluded and the criteria for positive identification satisfied; for this, he or she must rely on knowledge gained through education and experience. Ultimately, the conclusion will have to be substantiated beyond any reasonable doubt in a court of law. Comparison A comparison analysis subjects a suspect specimen and a standard/ reference specimen to the same tests and examinations for the ultimate purpose of determining whether they have a common origin. For example, the forensic scientist may place a suspect at a particular location by noting the similarities of a hair found at the crime scene to hairs removed from a suspect’s head (Figure 3–1). Or a paint chip found on a hit-and-run victim’s garment may be compared with paint removed from a vehicle suspected of being involved in the incident. The forensic comparison is actually a two-step procedure. First, combi- nations of select properties are chosen from the suspect and the standard/ reference specimen for comparison. The question of which and how many properties are selected obviously depends on the type of materials being examined. (This subject will receive a good deal of discussion in forthcom- ing chapters.) The overriding consideration must be the ultimate evidential value of the conclusion. This brings us to the second objective. Once the examination has been completed, the forensic scientist must draw a conclusion about the origins of the specimens. Do they or do they not come from the same source? Certainly if one or more of the properties selected for comparison do not individual characteristics Properties of evidence that can be attributed to a common source with an extremely high degree of certainty. 82 CHAPTER 3 agree, the analyst will conclude that the specimens are not the same and hence could not have originated from the same source. Suppose, on the other hand, that all the properties do compare and the specimens, as far as the examiner can determine, are indistinguishable. Does it logically follow that they come from the same source? Not necessarily so. To comprehend the evidential value of a comparison, one must appre- ciate the role that probability has in ascertaining the origins of two or more specimens. Simply defined, probability is the frequency of occurrence of an event. If a coin is flipped hundred times, in theory we can expect heads to come up fifty times. Hence, the probability of the event (heads) occurring is 50 in 100. In other words, probability defines the odds that a certain event will occur. Individual Characteristics Evidence that can be associated with a common source with an extremely high degree of probability is said to possess individual characteristics. Examples of such associations are the match- ing ridge characteristics of two fingerprints, the comparison of random striations (markings) on bullets or tool marks, the comparison of irregular and random wear patterns in tire or footwear impressions, the compari- son of handwriting characteristics, the fitting together of the irregular edges of broken objects in the manner of a jigsaw puzzle (see Figure 3–2), or matching sequentially made plastic bags by striation marks running across the bags (see Figure 3–3). FIGURE 3–2 The body of a woman was found with evidence of beating about the head and a stablike wound in the neck. Her husband was charged with the murder. The pathologist found a knife blade tip in the wound in the neck. The knife blade tip was compared with the broken blade of a penknife found in the trousers pocket of the accused. Note that in addition to the fit of the indentations on the edges, the scratch marks running across the blade tip correspond in detail to those on the broken blade. Courtesy Centre of Forensic Sciences, Toronto, Canada Physical Evidence 85 The Significance of Physical Evidence One of the current weaknesses of forensic science is the inability of the examiner to assign exact or even approximate probability values to the com- parison of most class physical evidence. For example, what is the proba- bility that a nylon fiber originated from a particular sweater, or that a hair came from a particular person’s head, or that a paint chip came from a car suspected to have been involved in a hit-and-run accident? Very few statistical data are available from which to derive this information, and in a society that is increasingly dependent on mass-produced products, the gathering of such data is becoming an increasingly elusive goal. One of the primary endeavors of forensic scientists must be to create and update statistical databases for evaluating the significance of class physical evidence. Of course, when such information—for example, the population frequency of blood factors—is available, it is used; but for the most part, the forensic scientist must rely on personal experience when interpreting the significance of class physical evidence. People who are unfamiliar with the realities of modern criminalistics are often disappointed to learn that most items of physical evidence retrieved at crime scenes cannot be linked definitively to a single person or object. Although investigators always try to uncover physical evidence with indi- vidual characteristics—such as fingerprints, tool marks, and bullets—the chances of finding class physical evidence are far greater. To deny or belit- tle the value of such evidence is to reject the potential role that criminalistics can play in a criminal investigation. In practice, criminal cases are fashioned for the courtroom around a collection of diverse elements, each pointing to the guilt or involvement of a party in a criminal act. Often, most of the evidence gathered is subjective, prone to human error and bias. The believability of eyewitness accounts, confessions, and informant testimony can all be disputed, maligned, and subjected to severe attack and skepticism in the courtroom. Under these circumstances, errors in human judgment are often magnified to detract from the credibility of the witness. Assessing the Value of Evidence The value of class physical evidence lies in its ability to corroborate events with data in a manner that is, as nearly as possible, free of human error and bias. It is the thread that binds together other investigative findings that are more dependent on human judgments and, therefore, more prone to human failings. The fact that scientists have not yet learned to individual- ize many kinds of physical evidence means that criminal investigators should not abdicate or falter in their pursuit of all investigative leads. How- ever, the ability of scientists to achieve a high degree of success in evaluat- ing class physical evidence means that criminal investigators can pursue their work with a much greater chance of success. Admittedly, defining the significance of an item of class evidence in exact mathematical terms is usually a difficult if not impossible goal. While class evidence is by its very nature not unique, meaningful items of physi- cal evidence, such as those listed at the beginning of this chapter, are extremely diverse in our environment. Select, for example, a colored fiber from an article of clothing and try to locate the exact same color on the clothing of random individuals you meet, or select a car color and try to 86 CHAPTER 3 FIGURE 3–4 Side-by-side comparison of fibers. Courtesy Chris Palenik, Microtrace, Elgin, IL., www.microtracescientific.com match it to other automobiles you see on local streets. Furthermore, keep in mind that a forensic comparison goes beyond a mere color comparison and involves examining and comparing a variety of chemical and/or phys- ical properties (Figure 3–4). The chances are low of encountering two in- distinguishable items of physical evidence at a crime scene that actually originated from different sources. Obviously, given these circumstances, only objects that exhibit significant diversity are appropriate for classifica- tion as physical evidence. In the same way, when one is dealing with more than one type of class evidence, their collective presence may lead to an extremely high certainty that they originated from the same source. As the number of different ob- jects linking an individual to a crime increases, the probability of involve- ment increases dramatically. A classic example of this situation can be found in the evidence presented at the trial of Wayne Williams (see the case reading at the end of this chapter). Wayne Williams was charged with the murders of two individuals in the Atlanta, Georgia, metropolitan area; he was also linked to the murders of ten other boys and young men. An es- sential element of the state’s case involved the association of Williams with the victims through a variety of fiber evidence. Actually, twenty-eight dif- ferent types of fibers linked Williams to the murder victims, evidence that the forensic examiner characterized as “overwhelming.” Cautions and Limitations in Dealing with Physical Evidence In further evaluating the contribution of physical evidence, one cannot overlook one important reality in the courtroom: The weight or signifi- cance accorded physical evidence is a determination left entirely to the trier of fact, usually a jury of laypeople. Given the high esteem in which sci- entists are generally held by society and the infallible image created for Physical Evidence 87 forensic science by books and television, scientifically evaluated evidence often takes on an aura of special reliability and trustworthiness in the courtroom. Often physical evidence, whether individual or class, is accorded great weight during jury deliberations and becomes a primary factor in re- inforcing or overcoming lingering doubts about guilt or innocence. In fact, a number of jurists have already cautioned against giving carte blanche approval to admitting scientific testimony without first considering its relevance to the case. Given the potential weight of scientific evidence, failure to take proper safeguards may unfairly prejudice a case against the accused. Physical evidence may also serve to exclude or exonerate a person from suspicion. For instance, if type A blood is linked to the suspect, all individ- uals who have types B, AB, and O blood can be eliminated from consider- ation. Because it is not possible to assess at the crime scene what value, if any, the scientist will find in the evidence collected, or what significance such findings will ultimately have to a jury, thorough collection and scien- tific evaluation of physical evidence must become a routine part of all crim- inal investigations. Just when an item of physical evidence crosses the line that distin- guishes class from individual is a difficult question to answer and is often the source of heated debate and honest disagreement among forensic sci- entists. How many striations are necessary to individualize a mark to a sin- gle tool and no other? How many color layers individualize a paint chip to a single car? How many ridge characteristics individualize a fingerprint, and how many handwriting characteristics tie a person to a signature? These questions defy simple answers. The task of the forensic scientist is to find as many characteristics as possible to compare one substance with an- other. The significance attached to the findings is decided by the quality and composition of the evidence, the case history, and the examiner’s ex- perience. Ultimately, the conclusion can range from mere speculation to near certainty. There are practical limits to the properties and characteristics the forensic scientist can select for comparison. Carried to the extreme, no two things in this world are alike in every detail. Modern analytical tech- niques have become so sophisticated and sensitive that the criminalist must define the limits of natural variation among materials when inter- preting the data gathered from a comparative analysis. For example, we will learn in the next chapter that two properties, density and refractive index, are best suited for comparing two pieces of glass. But the latest techniques that have been developed to measure these properties are so sensitive that they can even distinguish glass originating from a single pane of glass. Certainly this goes beyond the desires of a criminalist try- ing to determine only whether two glass particles originated from the same window. Similarly, if the surface of a paint chip is magnified 1,600 times with a powerful scanning electron microscope, it is apparent that the fine details that are revealed could not be duplicated in any other paint chip. Under these circumstances, no two paint chips, even those coming from the same surface, could ever compare in the true sense of the word. Therefore, practicality dictates that such examinations be con- ducted at a less revealing, but more meaningful, magnification (see Figure 3–5). Distinguishing evidential variations from natural variations is not always an easy task. Learning how to use the microscope and all the other modern instruments in a crime laboratory properly is one thing; gaining the proficiency needed to interpret the observations and data is another. As new 90 CHAPTER 3 Forensic Brief In 1975, police found Gerald Wallace’s body on his living room couch. He had been savagely beaten, his hands bound with an electric cord. Detectives searched his ransacked house, cataloging every piece of evidence they could find. None of it led to the murderer. They had no witnesses. Sixteen years after the fact, a lone fingerprint, lifted from a cigarette pack found in Wallace’s house and kept for sixteen years in the police files, was entered into the Pennsylvania State Police AFIS database. Within minutes, it hit a match. That print, police say, gave investigators the identity of a man who had been at the house the night of the murder. Police talked to him. He led them to other witnesses, who led them to the man police ultimately charged with the murder of Gerald Wallace. DNA Databases In 1998, the FBI’s Combined DNA Index System (CODIS) became fully op- erational. CODIS enables federal, state, and local crime laboratories to electronically exchange and compare DNA profiles, thereby linking crimes to each other and to convicted offenders. All fifty states have enacted leg- islation to establish a data bank containing DNA profiles of individuals convicted of felony sexual offenses (and other crimes, depending on each state’s statute). CODIS creates investigative leads from two sources: the forensic index and the offender index. The forensic index currently contains about 110,000 profiles from unsolved crime-scene evidence. Based on a match, police in multiple jurisdictions can identify serial crimes, allowing coordination of in- vestigations and sharing of leads developed independently. The offender FIGURE 3–6 The computerized search of a fingerprint database first requires that selected ridge characteristics be designated by a coder. The positions of these ridge characteristics serve as a basis for comparing the print against file fingerprints. Courtesy Sirchie Finger Print Laboratories, Inc., Youngsville, N.C., www.sirchie.com Latent Print File Print Physical Evidence 91 Forensic Brief Fort Collins, Colorado, and Philadelphia, Pennsylvania, are separated by nearly 1,800 miles, but in 2001 they were tragically linked though DNA. Troy Graves left the Philadelphia area in 1999, joined the Air Force, and settled down with his wife in Colorado. A frenzied string of eight sexual assaults around the Colorado University campus set off a manhunt that ultimately resulted in the arrest of Graves. However, his DNA profile inextricably identified him as Philadelphia’s notorious “Center City rapist.” This assailant attacked four women in 1997 and brutally murdered Shannon Schieber, a Wharton School graduate student, in 1998. His last known attack in Philadelphia was the rape of an 18-year-old student in August 1999, shortly before he left the city. In 2002 Graves was returned to Philadelphia, where he was sentenced to life in prison without parole. index contains the profiles of nearly three million convicted or arrested in- dividuals. (Unfortunately, hundreds of thousands of samples are back- logged, still awaiting DNA analysis and entry into the offender index.) Law enforcement agencies search this index against DNA profiles recovered from biological evidence found at unsolved crime scenes. This approach has been tremendously successful in identifying perpetrators because most crimes involving biological evidence are committed by repeat offenders. Several countries throughout the world have initiated national DNA data banks. The United Kingdom’s National DNA Database, established in 1995, was the world’s first national database. Currently it holds about three million profiles, and DNA can be taken for entry into the database from anyone arrested for an offense likely to involve a prison term. In a typical month, matches are found linking suspects to 26 murders; 57 rapes and other sexual offenses; and 3,000 motor vehicle, property and drug crimes. Other Databases The National Integrated Ballistics Information Network (NIBIN) maintained by the Bureau of Alcohol, Tobacco, Firearms and Explosives, allows firearms analysts to acquire, digitize, and compare markings made by a firearm on bullets and cartridge casings recovered from crime scenes. The NIBIN pro- gram currently has 236 sites that are electronically joined to sixteen multistate regions. The heart of NIBIN is the Integrated Ballistic Identification System (IBIS), comprising a microscope and a computer unit that can capture an image of a bullet or cartridge casing. The images are then forwarded to a regional server, where they are stored and correlated against other images in the regional database. IBIS does not positively match bullets or casings fired from the same weapon; this must be done by a firearms examiner. IBIS does, however, facilitate the work of the firearms examiner by pro- ducing a short list of candidates for the examiner to manually compare. Nearly 900,000 pieces of crime-scene evidence have been entered in NIBIN and more than 10,000 “hits” have been recorded, many of them yielding in- vestigative information not obtainable by other means. The International Forensic Automotive Paint Data Query (PDQ) data- base contains chemical and color information pertaining to original auto- motive paints. This database, developed and is maintained by the Forensic 92 CHAPTER 3 Laboratory Services of the Royal Canadian Mounted Police (RCMP), con- tains information about make, model, year, and assembly plant on more than 13,000 vehicles, with a library of more than 50,000 layers of paint. Contributors to the PDQ include the RCMP and forensic laboratories in Ontario and Quebec, as well as forty U.S. forensic laboratories and police agencies in twenty-one other countries. Accredited users of PDQ are required to submit sixty new automotive paint samples per year for addi- tion to the database. The PDQ database has found its greatest utility in the investigation of hit-and-runs by providing police with possible make, model, and year information to aid in the search for the unknown vehicle. The previously described databases are maintained and controlled by government agencies. There is one exception: a commercially available computer retrieval system for comparing and identifying crime-scene shoe prints known as SICAR (shoeprint image capture and retrieval).1 SICAR’s pattern-coding system enables an analyst to create a simple description of a shoe print by assigning codes to individual pattern features (see Figure 3–7). Shoe print images can be entered into SICAR by either a scan- ner or a digital camera. This product has a comprehensive shoe sole data- base that includes more than three hundred manufacturers of shoes with more than eight thousand different sole patterns, providing investigators with a means for linking a crime-scene footwear impression to a particular shoe manufacturer. Key Points • The creation of computerized databases for fingerprints, criminal his- tories, DNA profiles, markings on bullets and cartridges, automotive paints, and shoe prints has dramatically enhanced the role of forensic science in criminal investigation. • IAFIS is the Integrated Automated Fingerprint Identification System, a national fingerprint and criminal history database maintained by the FBI. IAFIS allows criminal investigators to compare fingerprints at a crime scene to an index of 500 million known prints. CODIS is the FBI’s Combined DNA Index System. It enables federal, state, and local crime laboratories to electronically exchange and compare DNA profiles, linking crimes to each other and to convicted offenders. Forensic Brief After a series of armed robberies in which suspects fired shots, the sheriff’s office of Broward County, Florida, entered the cartridge casings from the crime scenes into NIBIN. Through NIBIN, four of the armed robberies were linked to the same 40-caliber handgun. A short time later, sheriff’s deputies noticed suspicious activity around a local business. When they attempted to interview the suspects, the suspects fled in a vehicle. During the chase, the suspects attempted to dispose of a handgun; deputies recovered the gun after making the arrests. The gun was test-fired and the resulting evidence entered into NIBIN, which indicated a possible link between this handgun and the four previous armed robberies. Firearms examiners confirmed the link by examining the original evidence. The suspects were arrested and charged with four prior armed robbery offenses. Physical Evidence 95 Crime-Scene Reconstruction Criminalists Medical Examiners Law Enforcement Personnel FIGURE 3–9 Crime-scene reconstruction relies on the combined efforts of medical examiners, criminalists, and law enforcement personnel to recover physical evidence and to sort out the events surrounding the occurrence of a crime. the victim was clothed after death, because livor will not develop within ar- eas of the body that are restricted by clothing. Such determinations can of- ten reveal pertinent information that will aid the investigation. A criminalist or trained crime-scene investigator can also bring special skills to the reconstruction of events that occurred during the commission of a crime. For example, a criminalist using a laser beam to plot the approxi- mate bullet path in trajectory analysis can help determine the probable po- sition of the shooter relative to that of the victim (see Figure 3–8). Other skills that a criminalist may employ during a crime-scene reconstruction analysis include blood spatter analysis (discussed more fully in Chapter 8), deter- mining the direction of impact of projectiles penetrating glass objects (Chapter 4), locating gunshot residues deposited on the victim’s clothing to estimate the distance of a shooter from a target, and searching for primer residues deposited on the hands of a suspect shooter (both covered in Chapter 15). Reconstruction is a team effort that involves putting together many dif- ferent pieces of a puzzle (see Figure 3–9). The right connections must be made among all the parts involved so as to portray the relationship among the victim, the suspect, and the crime scene. If successful, reconstruction can play a vital role in helping a jury arrive at an appropriate verdict. Key Points • Crime-scene reconstruction relies on the combined efforts of medical examiners, criminalists, and law enforcement personnel to recover physical evidence and to sort out the events surrounding the occur- rence of a crime. • Examples of crime scene reconstruction include determining whether a body was moved after death, determining whether a victim was clothed after death, analyzing bullet trajectory, analyzing blood spatter, determining the direction from which projectiles penetrated glass ob- jects, estimating the distance of a shooter from a target, and locating primer residue on suspects. 96 CHAPTER 3 Chapter Summary Physical evidence is usually examined by a forensic scientist for identification or comparison. The object of identification is to determine the physical or chemical identity with as near absolute certainty as existing analytical techniques will permit. Identification first requires the adoption of testing procedures that give characteristic results for specific standard/reference materials. Once this is done, the examiner uses an appropriate number of tests to identify a substance and exclude all other substances from consid- eration. The identification process is normally used in crime laboratories to identify drugs, explosives, and petroleum products. Also, evidence such as blood, semen, or hair is routinely identified in a crime laboratory. Normally these identifications include a determination for species origin (such as human blood or rabbit hair). A comparative analysis has the important role of determining whether a suspect specimen and a standard/reference specimen have a common origin. Both the standard/reference and the suspect specimen are subject to the same tests. Evidence that can be associated with a common source with an extremely high degree of probability is said to possess individual characteristics. Evidence associated only with a group is said to have class characteristics. Nevertheless, the high diversity of class evidence in our environment makes their comparison very significant in the context of a criminal investigation. As the number of different objects linking an indi- vidual to a crime scene increases, so does the likelihood of that individual’s involvement with the crime. Importantly, a person may be exonerated or excluded from suspicion if physical evidence collected at a crime scene is found to be different from standard/reference samples collected from that subject. A dramatic enhancement of the role of forensic science in criminal in- vestigation has come about through the creation of computerized databases. The Integrated Automated Fingerprint Identification System (IAFIS), a national fingerprint and criminal history system, is maintained by the FBI. The FBI’s Combined DNA Index System (CODIS) enables federal, state, and local crime laboratories to electronically exchange and compare DNA profiles, thereby linking crimes to each other and to convicted offenders. The National Integrated Ballistics Information Network (NIBIN), main- tained by the Bureau of Alcohol, Tobacco, Firearms and Explosives, allows firearms analysts to acquire, digitize, and compare markings made by a firearm on bullets and cartridge casings recovered from crime scenes. The International Forensic Automotive Paint Data Query (PDQ) database con- tains chemical and color information pertaining to original automotive paints. SICAR (shoeprint image capture and retrieval) has a comprehensive shoe sole database. Physical evidence left behind at a crime scene, properly handled and preserved, plays a crucial role in reconstructing the events that took place surrounding the crime. Crime-scene reconstruction relies on the com- bined efforts of medical examiners, criminalists, and law enforcement per- sonnel to recover physical evidence and to sort out the events surrounding the occurrence of a crime. Physical Evidence 97 Review Questions Facts and Concepts 1. List five examples of each of the following types of physical evidence: biolog- ical materials, impressions, and manufactured items. 2. What is the purpose of identification? What are the two main requirements for identification? 3. List three reasons why it is not possible to define a simple analytical scheme that can be applied to all types of evidence. 4. What is a comparison analysis? What are the two steps in comparison? 5. Define individual characteristics and give two examples. 6. Define class characteristics and give two examples. 7. State the product rule and explain how it applies to the comparison of physi- cal evidence. 8. Explain how the product rule is relevant to the murder conviction of Wayne Williams. 9. What is the greatest weakness of class physical evidence? What is the main reason for this weakness? 10. What is the greatest value of class physical evidence? 11. Who ultimately determines the significance of physical evidence in a trial? a. the judge b. expert witnesses c. the Supreme Court d. the jury 12. State two reasons why it is important to consider the relevance of scientific evidence before allowing it to be introduced into a criminal case. 13. Why does a forensic scientist often opt not to use the most sensitive analyti- cal techniques when comparing suspect substances? 14. What is a forensic database and how are such databases useful to criminalists? 15. Name three forensic databases and describe the type of information stored in each. 16. Describe the difference between the forensic and offender indexes in the CODIS database. 17. What is crime-scene reconstruction? 18. In which of the following ways can physical evidence aid in crime-scene re- construction? (You may choose more than one response.) a. by supporting or contradicting statements given by witnesses and/or suspects b. by describing exactly what happened at the crime scene c. by confirming the accuracy of a crime-scene reconstruction to a jury d. by distinguishing between individual and class characteristics e. by generating leads that may help investigators solve the case 100 CHAPTER 3 Case Reading Fiber Evidence and the Wayne Williams Trial On February 26, 1982, a Fulton County, Ga., Superior Court jury returned a verdict of “guilty as charged” on two counts of murder brought against Wayne Bertram Williams by a Fulton County grand jury in July 1981. Williams had been on trial since December 28, 1981, for the asphyxial murders of Nathaniel Cater and Jimmy Payne in April and May of 1981. During the 8-week trial, evidence linking Williams to those murders and to the murders of 10 other boys or young men was introduced. An essential part of this case, presented by the Fulton County District Attorney’s Office, involved the association of fibrous debris removed from the bodies of 12 murder victims with objects from the everyday environment of Williams. Fiber evidence has often been an important part of criminal cases, but the Williams trial differed from other cases in several respects. Fiber evidence has not played a significant role in any case involving a large number of murder victims. The victims whose deaths were charged to Williams were 2 of 30 black children and black young men who were reported missing or who had died under suspicious circumstances in the Atlanta area over a 22-month period beginning in July 1979. During the trial, fiber evidence was used to associate Williams with 12 of those victims. Fiber evidence is often used to corroborate other evidence in a case—it is used to support other testimony and validate other evidence presented at a trial. This was not the situation in the Williams trial. Other Wayne Williams is shown talking to police outside his home. Courtesy Corbis Bettmann Reprinted in part from FBI Law Enforcement Bulletin, March and May 1984. Harold A. Deadman Special Agent, Microscopic Analysis Unit, Laboratory Division Federal Bureau of Investigation, Washington, D.C. Physical Evidence 101 evidence and other aspects of the trial were important but were used to support and complement the fiber evidence, not the usual order of things. The “hair and fiber matches” between Williams’s environment and 11 of the 12 murder victims discussed at the trial were so significant that, in the author’s opinion, these victims were positively linked to both the residence and automobiles that were a major part of the world of Wayne Williams. Another difference between this case and most other cases was the extremely large amount of publicity surrounding both the investigation of the missing and murdered children and the arrest and subsequent trial of Williams. Few other murder trials have received the attention that the Williams case received. . . . It is often difficult to get an accurate picture from press reports of the physical evidence introduced at a trial and the significance of that evidence. This article will also set forth in some detail the fiber evidence that linked Williams to the murder victims. By discussing only the fiber evidence introduced at the trial, many other aspects of the case against Williams are being neglected. Additional evidence dealing with Williams’s motivations—his character and behavior, his association with several of the victims by eyewitness accounts, and his link to a victim recovered from a river in Atlanta—was also essential to the case. . . . Development of Williams as a Murder Suspect Before Wayne Williams became a suspect in the Nathaniel Cater murder case, the Georgia State Crime Laboratory located a number of yellowish-green nylon fibers and some violet acetate fibers on the bodies and clothing of the murder victims whose bodies had been recovered during the period of July 1979 to May 1981. The names of those victims were included on the list of missing and murdered children that was compiled by the Atlanta Task Force (a large group of investigators from law enforcement agencies in the Atlanta area). The yellowish-green nylon fibers were generally similar to each other in appearance and properties and were considered to have originated from a single source. This was also true of the violet acetate fibers. Although there were many other similarities that would link these murders together, the fiber linkage was notable since the possibility existed that a source of these fibers might be located in the future. Initially, the major concern with these yellowish-green nylon fibers was determining what type of object could have been their source. This information could provide avenues of investigative activity. The fibers were very coarse and had a lobed cross- sectional appearance, tending to indicate that they originated from a carpet or a rug. The lobed cross-sectional shape of these fibers, however, was unique, and initially, the manufacturer of these fibers could not be determined. Photomicrographs of the fibers were prepared for display to contacts within the textile industry. On one occasion, these photomicrographs were distributed among several chemists attending a meeting at the research facilities of a large fiber producer. The chemists concurred that the yellowish- green nylon fiber was very unusual in cross- sectional shape and was consistent with being a carpet fiber, but again, the manufacturer of this fiber could not be determined. Contacts with other textile producers and textile chemists likewise did not result in an identification of the manufacturer. 102 CHAPTER 3 In February 1981, an Atlanta newspaper article publicized that several different fiber types had been found on two murder victims. Following the publication of this article, bodies recovered from rivers in the Atlanta metropolitan area were either nude or clothed only in undershorts. It appeared possible that the victims were being disposed of in this undressed state and in rivers in order to eliminate fibers from being found on their bodies.1 On May 22, 1981, a four-man surveillance team of personnel from the Atlanta Police Department and the Atlanta Office of the FBI was situated under and at both ends of the James Jackson Parkway Bridge over the Chattahoochee River in northwest Atlanta. Around 2 a.m., a loud splash alerted the surveillance team to the presence of an automobile being driven slowly off the bridge. The driver was stopped and identified as Wayne Bertram Williams. Two days after Williams’s presence on the bridge, the nude body of Nathaniel Cater was pulled from the Chattahoochee River, approximately 1 mile downstream from the James Jackson Parkway Bridge. A yellowish- green nylon carpet-type fiber, similar to the nylon fibers discussed above, was recovered from the head hair of Nathaniel Cater. When details of Williams’s reason for being on the bridge at 2 a.m. could not be confirmed, search warrants for Williams’s home and automobile were obtained and were served on the afternoon of June 3, 1981. During the late evening hours of the same day, the initial associations of fibers from Cater and other murder victims were made with a green carpet in the home of Williams. Associations with a bedspread from Williams’s bed and with [Williams’s] family dog were also made at that time. An apparent source of the yellowish-green nylon fibers had been found. It now became important to completely characterize these fibers in order to verify the associations and determine the strength of the associations resulting from the fiber matches. Because of the unusual cross-sectional appearance of the nylon fiber and the difficulty in determining the manufacturer, it was believed that this was a relatively rare fiber type, and therefore, would not be present in large amounts (or in a large number of carpets). [Williams’s] Carpet Shortly after Williams was developed as a suspect, it was determined the yellowish- green nylon fibers were manufactured by the Wellman Corporation. The next step was to ascertain, if possible, how much carpet like Williams’s bedroom carpet had been sold in the Atlanta area—carpet composed of the Wellman fiber and dyed with the same dye formulation as [Williams’s] carpet. Names of Wellman Corporation customers who had purchased this fiber type, technical information about the fiber, and data concerning when and how much of this fiber type had been manufactured were obtained. It was confirmed that the Wellman Corporation had, in fact, manufactured the fiber in Williams’s carpet and that no other fiber manufacturer was known to have made a fiber with a similar cross section. It was also determined that fibers having this cross-sectional shape were manufactured and sold during the years 1967 through 1974. Prior to 1967, this company manufactured only a round cross section; after 1974, the unusual trilobal cross section seen in Williams’s carpet was modified to a more regular trilobal cross-sectional shape. A list of sales of that fiber type during the period 1967 through 1974 was compiled. . . . Through numerous contacts with yarn spinners and carpet manufacturers, it was Physical Evidence 105 representatives from the Wellman and West Point Pepperell Corporations, were involved in educating the jury regarding textile fibers in general and helped lay the foundation for the conclusions of the forensic fiber examiners. The jury also was told about fiber analysis in the crime laboratory. The trial, as it developed, can be divided into two parts. Initially, testimony was given concerning the murders of Nathaniel Cater and Jimmy Ray Payne, the two victims included in the indictment drawn against Williams in July 1981. Testimony was then given concerning Williams’s association with 10 other murder victims. The fiber matches made between fibers in Williams’s environment and fibers from victims Payne and Cater were discussed. The items from Williams’s environment that were linked to either or both of the victims are shown in the center of the chart. (See Figure 1.) Not only is Payne linked to Williams’s environment by seven items and Cater linked by six items, but both of the victims are linked strongly to each other based on the fiber matches and circumstances surrounding their deaths. In discussing the significance or strength of an association based on textile fibers, it was emphasized that the more uncommon the fibers, the stronger the association. None of the fiber types from the items in Williams’s environment shown in the center of Figure 1 is by definition a “common” fiber type. Several of the fiber types would be termed “uncommon.” One of the fibers linking the body of Jimmy Ray Payne to the carpet in the 1970 station wagon driven by Williams was a small rayon fiber fragment recovered from Payne’s shorts. Data were obtained from the station wagon’s manufacturer concerning which automobile models produced prior to 1973 contained carpet made of this fiber type. These data were coupled with additional information from Georgia concerning the number of these models registered in the Atlanta metropolitan STATION WAGON: CARPET THROW RUG BLUE RAYON FIBERS ITEMS FROM RESIDENCE AND STATION WAGON OF WAYNE WILLIAMS JIMMY RAY PAYNE Black male (21) 5'7", 135 lbs. Body recovered Chattahoochee River near I–85, 4/27/81 Death by Asphyxiation NATHANIEL CATER Black male (28) 5'11", 146 lbs. Body recovered Chattahoochee River near I–85, 5/24/81 Death by Asphyxiation BACKROOM: CARPET SQUARE YELLOW-GREEN SYNTHETIC FIBERS BEDROOM: BEDSPREAD BEDROOM CARPET BLANKET FROM UNDER BED WILLIAMS FAMILY DOG FIGURE 1 Items from residence and station wagon of Wayne Williams that were found on Jimmy Ray Payne and Nathaniel Cater. 106 CHAPTER 3 area during 1981. This allowed a calculation to be made relating to the probability of randomly selecting an automobile having carpet like that in the 1970 Chevrolet station wagon from the 2,373,512 cars registered in the Atlanta metropolitan area. This probability is 1 chance in 3,828, a very low probability representing a significant association. Another factor to consider when assessing the significance of fiber evidence is the increased strength of the association when multiple fiber matches become the basis of the association. This is true if different fiber types from more than one object are found and each fiber type either links two people together or links an individual with a particular environment. As the number of different objects increases, the strength of an association increases dramatically. That is, the chance of randomly finding several particular fiber types in a certain location is much smaller than the chance of finding one particular fiber type. The following example can be used to illustrate the significance of multiple fiber matches linking two items together. If one were to throw a single die one time, the chance or probability of throwing a particular number would be one chance in six. The probability of throwing a second die and getting that same number also would be one chance in six. However, the probability of getting 2 of the same numbers on 2 dice thrown simultaneously is only 1 in every 36 double throws—a much smaller chance than with either of the single throws. This number is a result of the product rule of probability theory. That is, the probability of the joint occurrence of a number of mutually independent events equals the product of the individual probabilities of each of the events (in this example—1/6  1/6  1/36). Since numerous fiber types are in existence, the chance of finding one particular fiber type, other than a common type, in a specific randomly selected location is small. The chance then of finding several fiber types together in a specific location is the product of several small probabilities, resulting in an extremely small chance. . . . However, no attempt was made to use the product rule and multiply the individual probability numbers together to get an approximation of the probability of finding carpets like Williams’s residential carpet and Williams’s automobile carpet in the same household. The probability numbers were used only to show that the individual fiber types involved in these associations were very uncommon. . . .6 In addition to the two probability numbers already discussed (bedroom and station wagon carpets), each of the other fiber types linking Williams to both Cater and Payne has a probability of being found in a particular location. The chance of finding all of the fiber types indicated on the chart [Figure 1] in one location (seven types on Payne’s body and six types on Cater’s body) would be extremely small. Although an actual probability number for those findings could not be determined, it is believed that the multiple fiber associations shown on this chart are proof that Williams is linked to the bodies of these two victims, even though each fiber match by itself does not show a positive association with Williams’s environment. Studies have been conducted in England that show that transferred fibers are usually lost rapidly as people go about their daily routine.7 Therefore, the foreign fibers present on a person are most often from recent surroundings. The fibrous debris found on a murder victim reflects the body’s more recent surroundings, Physical Evidence 107 especially important if the body was moved after the killing. Accordingly, the victims’ bodies in this particular case are not only associated with Williams but are apparently associated with Williams shortly before or after their deaths. It was also pointed out during the trial that the locations of the fibers—on Payne’s shorts and in Cater’s head hairs and pubic hairs—were not those where one would expect to find fibrous debris transferred from an automobile or a house to victims who had been fully clothed. Although from these findings it would appear that the victims were in the residence of Williams, there was one other location that contained many of the same fibers as those in the composition of various objects in his residence—Williams’s station wagon. The environment of a family automobile might be expected to reflect, to some extent, fibers from objects located within the residence. This was true of the 1970 station wagon. With one exception, all of the fiber types removed from Payne and Cater, consistent with originating from items shown in the center of Figure 1, were present in debris removed by vacuuming the station wagon. The automobile would be the most logical source of the foreign fibers found on both Payne and Cater if they were associated with Williams shortly before or after their deaths. It should also be pointed out that two objects, the bedspread and the blanket, were portable and could have at one time been present inside the station wagon. Both Payne and Cater were recovered from the Chattahoochee River. Their bodies had been in the water for several days. Some of the fibers found on these victims were like fibers in the compositions of the bedroom carpet and bedspread except for color intensity. They appeared to have been bleached. By subjecting various known fibers to small amounts of Chattahoochee River water for different periods of time, it was found that bleaching did occur. This was especially true with the carpet and bedspread fibers from Williams’s bedroom. Two crime laboratory examiners testified during the closing stages of the first part of the trial about Williams’s association with Payne and Cater. They concluded that it was highly unlikely that any environment other than that present in Wayne Williams’s house and car could have resulted in the combination of fibers and hairs found on the victims and that it would be virtually impossible to have matched so many fibers found on Cater and Payne to items in Williams’s house and car unless the victims were in contact with or in some way associated with the environment of Wayne Williams. After testimony was presented concerning the Payne and Cater cases, the Fulton County District Attorney’s Office asked the court to be allowed to introduce evidence in the cases of 10 other victims whose murders were similar in many respects. Georgia law allows evidence of another crime to be introduced “. . . if some logical connection can be shown between the two from which it can be said that proof of the one tends to establish the other as relevant to some fact other than general bad character.”8 There need be no conviction for the other crime in order for details about that crime to be admissible. It was ruled that evidence concerning other murders could be introduced in an attempt to prove a “pattern or scheme” of killing that included the two murders with which Williams was charged. The additional evidence in these cases was to be used to help the jury “. . . decide whether Williams had committed the two murders with which he is charged.”9 110 CHAPTER 3 been determined. Fibers consistent with having originated from both of these “unusual” carpets were recovered from Payne’s body. Of the 9 victims who were killed during the time period when Williams had access to the 1970 station wagon, fibers consistent with having originated from both the station wagon carpet and the bedroom carpet were recovered from 6 of these victims. The apparent bleaching of several fibers removed from the bodies of Payne and Cater was consistent with having been caused by river water. Several fibers similar to those from Payne and Cater were removed from many of the victims whose bodies were recovered on land. Consistent with the bleaching argument, none of the fibers from the victims found on land showed any apparent bleaching. The finding of many of the same fiber types on the remaining victims, who were recovered from many different locations, refutes the possibility that Payne’s and Cater’s bodies picked up foreign fibers from the river. The fact that many of the victims were involved with so many of the same fiber types, all of which linked the victims to Williams’s environment, is the basis for arguing conclusively against these fibers originating from a source other than Williams’s environment. It is hoped that this article has provided valuable insight concerning the use of fiber evidence in a criminal trial, has provided answers to questions from those in the law enforcement community about textile fiber evidence in general, and has presented convincing arguments to establish Wayne Williams’s association with the bodies of the murder victims. acetate fibers blended together in a single textile material, as in the bedspread, is in itself uncommon. . . . The previous discussion concerning the significance of multiple fiber matches can be applied to the associations made in the cases of all the victims except Bell, but especially to the association of Patrick Baltazar to Williams’s environment. Fibers and animal hairs consistent with having originated from 10 sources were removed from Baltazar’s body. These 10 sources include the uncommon bedroom carpet and station wagon carpet. In addition to the fiber (and animal hair) linkage, two head hairs of Negroid origin were removed from Baltazar’s body that were consistent with originating from the scalp area of Williams. Head hair matches were also very significant in linking Williams to Baltazar’s body. In the opinion of the author, the association based upon the hair and fiber analyses is a positive association. Another important aspect of the fiber linkage between Williams and these victims is the correspondence between the fiber findings and the time periods during which Williams had access to the three automobiles listed on the chart. Nine victims are linked to automobiles used by the Williams family. When Williams did not have access to a particular car, no fibers were recovered that were consistent with having originated from that automobile. Trunk liner fibers of the type used in the trunks of many late- model Ford Motor Company automobiles were also recovered from the bodies of two victims. One final point should be made concerning Williams’s bedroom and station wagon carpets where probability numbers had Physical Evidence 111 Endnotes 1. Prior to the publication of the February 11, 1981, newspaper article, one victim from the task force list, who was fully clothed, had been recovered from a river in the Atlanta area. In the 21/2-month period after publication, the nude or nearly nude bodies of 7 of the 9 victims added to the task force list were recovered from rivers in the Atlanta area. 2. J. Mitchell and D. Holland, “An Unusual Case of Identification of Transferred Fibers,” Journal of the Forensic Science Society, vol. 19, 1979, p. 23.This article describes a case in which carpet fibers transferred to a murder victim’s body in England were traced back to the carpet manufacturer and finally to an automobile owned by the person who eventually confessed to the murder. 3. This information was taken from a study by E. I. du Pont de Nemours & Co. concerned with the exist- ing residential floor space with carpet in the United States. This study was reported in a marketing sur- vey conducted by the Marketing Corporation of America, Westport, Conn. 4. Information regarding the number of housing units in the Atlanta metropolitan area was obtained from a report provided by the Atlanta Regional Commission. The report, dated November 11, 1981, contained population and housing counts for counties, super districts, and census tracts in the Atlanta metropolitan area. 5. Information about carpet similar to Williams’s car- pet was developed through contacts with carpet manufacturers and carpet salesmen in Georgia. It was determined that this type carpet was often in- stalled in commercial settings, such as apartments, and in those settings, had an average life span of 4 to 5 years. 6. Joseph L. Peterson, ed., Forensic Science (New York: AMS Press, 1975), pp. 181–225. This collec- tion of articles, dealing with various aspects of forensic science, contains five papers concerned with using statistics to interpret the meaning of physical evidence. It is a good discussion of prob- ability theory and reviews cases where probability theory has been used in trial situations. 7. C. A. Pounds and K. W. Smalldon, “The Transfer of Fibers between Clothing Materials During Simu- lated Contacts and Their Persistence During Wear,” Journal of the Forensic Science Society, vol. 15, 1975, pp. 29–37. 8. Encyclopedia of Georgia Law, vol. 11A (The Harrison Company, 1979), p. 70. 9. The Atlanta Constitution, “Williams Jury Told of Other Slayings,” Sec. 1A, 1/26/82, p. 25.