Types Of Evidence PDF

kh00116_CH02.indd Page 32 7/17/08 4:12:14 PM elhi-8 /Volumes/110/KHUS021/indd%0/Ch 02 Chapter 2 Types of Evidence Objectives After reading this chapter, you will understand: The val...

kh00116_CH02.indd Page 32 7/17/08 4:12:14 PM elhi-8 /Volumes/110/KHUS021/indd%0/Ch 02 Chapter 2 Types of Evidence Objectives After reading this chapter, you will understand: The value of indirect and direct evidence in a court of law. That eyewitness accounts have limitations. What physical evidence can and cannot prove in court. That the forensic scientist’s main goal is to find a unique source for the evidence. You will be able to: Explain the difference between indirect and direct evidence. Describe what is meant by physical evidence and give examples. Distinguish individual evidence from class evidence. Determine the significance of class evidence. 32 kh00116_CH02.indd Page 33 7/17/08 4:12:26 PM elhi-8 /Volumes/110/KHUS021/indd%0/Ch 02 “You can observe a lot just by watching.” —Yogi Berra, former New York Yankees catcher and sage 33 kh00116_CH02.indd Page Sec1:34 7/17/08 4:12:31 PM elhi-8 /Volumes/110/KHUS021/indd%0/Ch 02 Evidence Teacher Note The TRCD for this chapter Evidence can be divided into two general types: includes a PowerPoint presentation, which 1. Testimonial evidence is a statement made is an overview of the evidence: something that tends to establish or disprove a fact. under oath. An example would be a witness chapter. It can be used as introductory Evidence can include documents, pointing to someone in the courtroom and material or at the testimony, and other objects saying, “That’s the guy I saw robbing the end as a review. grocery store.” This is also called direct evidence testimonial evidence: what is said in court by a competent or prima facie evidence. witness; also called direct evidence 2. Physical evidence can be any object or or prima facie evidence material relevant in a crime. It can be any physical evidence: tangible tangible thing, large or small. This is also called items that tend to prove some real evidence. material fact; also called real evidence Classroom Activity How accurate are eyewitness Testimonial or Direct Evidence accounts? You can arrange an “intrusion” into the class by Eyewitness accounts can provide important evidence leading to the arrest someone the students don’t of a criminal. Juries are heavily influenced by eyewitness identification. How know. Make an arrangement with accurate are eyewitnesses? What might influence the “intruder” before In a 1977 study of more than their accuracy? Eyewitnesses can make perceptual class to come in and 2,000 lineups, of the 45 percent errors for many reasons: The crime scene may make some kind of of potential offenders who were have been too dark, the encounter may have been disturbance. Also, “recognized,” 82 percent were have a colleague call convicted. In 347 cases, where too brief, or the presence of a weapon may have on the house phone eyewitness testimony was the diverted the eyewitness’s attention. The stress and or the teacher’s cell only evidence, 74 percent of fear involved in witnessing a crime may sharpen phone, interrupting defendants were convicted. some people’s focus and confuse others. Errors class three times. Another report, in 1983, showed Write the wrong date that jurors relied more on in the memory process are also common. The on the chalkboard eyewitness testimony than on time between the crime and questioning of the before class, erase fingerprint evidence. witness can affect what he or she remembers. New it during class, information can influence memory, as when, for and replace it with another wrong date. During all example, viewing mug shots or being asked leading or suggestive questions. of these staged intrusions, have These kinds of new information can actually change the memory of a a class discussion or activity on witness, even one who is trying to be fair and honest. the different types of evidence that may be collected at several Police need to be careful in judging how reliable an eyewitness account different types of crime scenes. might be. Important points to consider include: The type of crime and how the witness saw it. Research has found that witnesses are more accurate in remembering some characteristics, such as sex and hair color, than others, such as age, height, and specific race. 34 Chapter 2 kh00116_CH02.indd Page Sec1:35 7/17/08 4:12:31 PM elhi-8 /Volumes/110/KHUS021/indd%0/Ch 02 Classroom Activity, continued Near the end of the class, ask students to clear their desks, take out a piece of paper, and answer the following questions: What time did the intruder come in? What did the intruder look like? Include height, weight, age, hair color, and hairstyle. Describe what the intruder was wearing. What did the intruder do? What conversation took place? At what times did the phone calls take place? How long did they last? What was said? An expert witness testifying in court What was the date on the board at the beginning of class? A witness who is physically similar to the offender is more likely to After students have been given give an accurate description. enough time to write down their answers, discuss this exercise Victims of serious crimes sometimes have a more accurate memory as a class. Make comparisons. over a long period of time because they tend to relive the event in How accurate were the students’ their minds. The presence of a weapon or the threat of violence also observations? How accurate influences recall because it may sharpen the witness’s focus. Any type would they be if they had to wait another day before they were of stress tends to narrow the focus, closing out secondary information. asked? Have students write down Some types of witness are better at remembering than others. Children what the person in front of them usually don’t remember as well as adults do. How accurate a child (or teacher, or person to the right, left, or behind) was wearing witness’s testimony is may depend on how he or she is interviewed. on the previous day. How many Because older adults may have poorer eyesight or hearing than do middle- accounts are accurate? aged or younger adults, their eyewitness accounts may be less accurate. Now ask the students to think Learning disabilities, mental disorders, alcohol or drugs, or head injury about how accurate their can all weaken memory and recall. observations would be if it were dark outside or if they were a fair Interviewing techniques or how information is retrieved can also make distance away and witnessing a a difference in the accuracy of an eyewitness’s story. Research has crime. Would a heightened state suggested that eyewitnesses are better at answering questions about of anxiety make their observations more or less accurate? An what happened than they are at questions about the description of the extension of this activity would offender. A witness’s report about the offender’s actions can be accurate be to ask the question: Are there even when there are few good details about what the offender looks like. any studies or statistics on the accuracy of eyewitness accounts? Open-ended questions often get better answers. It may be better to ask A few days of research in the the witness to describe what the offender was wearing than to ask what library or on the Web may answer color the offender’s shirt was. A careful choice of words can influence this question. memory. Leading questions such as “Was the offender’s shirt red?” can actually lessen accuracy. A confident witness is more likely to be accurate, although this isn’t always true. Generally, if a witness claims to be “absolutely certain” about something, then it is likely to be true. Types of Evidence 35 kh00116_CH02.indd Page Sec1:36 7/17/08 4:12:35 PM elhi-8 /Volumes/110/KHUS021/indd%0/Ch 02 Teacher Note There are also other factors to think about FACES 4.0 is a computer program when weighing an eyewitness account: that can be used to compose faces from thousands of features. Whether the witness already Students love it, and it can be knew the accused, and what their used to re-create a likeness of relationship had been a suspect, or themselves. This demonstrates how difficult it is How much time passed between the to describe subtle differences offense and the identification in facial features. It is available from its creator, Whether the IQ Biometrix witness had Facial image created by computer (www.iqbiometrix. Dumb Crooks already identified com), or from Two Kentucky men tried to pull (or failed to many other the front off a cash machine by scientific supply identify) the defendant running a chain from the machine firms, for example, to their pickup truck. Instead, Whether the witness had already identified Science Kit they pulled the bumper off the someone else & Boreal truck. They panicked, fled, and Laboratories left the chain still attached to the (www.sciencekit. Most known cases of an innocent person being machine and their bumper (with com). the license plate still attached). convicted happened because of a mistaken eyewitness identification. Physical Evidence The forensic scientist is most interested in physical evidence. It is the task of the forensic scientist to look at evidence and determine its identity and its origin. In identifying what a particular piece of evidence is, a scientist determines its physical and chemical properties. Physical properties, such as color, density, solubility, hardness, and refractive index, can often be observed or measured. Chemical properties can be observed when the object or substance changes its chemical composition. Often chemical properties are observed when the substance reacts with other chemicals. Examples of chemical changes or reactions are the formation of bubbles, color change, pH change, and the formation of a precipitate. Determining the origin of evidence almost always 36 Chapter 2 kh00116_CH02.indd Page 37 8/5/08 5:59:04 PM u-s081 /Volumes/110/KHUS021/indd%0/Ch 02 Table 2.1: Common Types of Physical Evidence drugs and toxic substances resins, plastics fingerprints paints explosive residues hair gunshot residues serial numbers tissues firearms and ammunition documents pollen impressions (shoe prints, bite fibers wood material marks, and the like) soil feathers petroleum products glass bones alcohols (especially ethanol) blood tool marks rubber material body fluids involves a comparison of the substance or object itself with GO TO www.scilinks.org something similar or the same that has a known origin. TOPIC crime scene Physical evidence can be any material or object (see Table 2.1). evidence It can take on almost any form: as large as a building, as CODE forensics2E37 fleeting as an odor, as small as a hair, or even submicroscopic, like DNA evidence. The variety of physical evidence is virtually unlimited, as is the uniqueness of the crime. Physical evidence is generally much more reliable than testimonial evidence. Case 2.1 illustrates how some convictions are based solely on eyewitness accounts. Note how the defense did indeed challenge the accuracy of the eyewitness accounts, but the court accepted the testimony as fact. 2.1: Coral Eugene Watts Confessed serial killer Coral Eugene Watts had served almost 20 years of a 60-year sentence when authorities began to worry about his possible release from prison. In 1982, Watts was convicted in Texas of burglary and intent to murder. Due to mandatory release laws and good behavior, an appeals court shortened his term to 25 years. He was scheduled to be released in May of 2006. In a plea bargain agreement, Watts had confessed to killing 13 women and received immunity for 12 of them. Police had identified Watts as a suspect in the killings, but said that it was difficult to build a case against him because he had used different methods to kill, never sexually assaulted the women, and chose strangers. Authorities stated that they lacked evidence to support their suspicions. Watts killed within minutes of encountering his victims, leaving very little evidence behind. Due to this lack of evidence, police stated that obtaining Watts, 2004 Types of Evidence 37 kh00116_CH02.indd Page Sec1:38 7/17/08 4:12:38 PM elhi-8 /Volumes/110/KHUS021/indd%0/Ch 02 Watts’s confession was the only way to close open murder cases and get answers for grieving relatives. The murders that Watts had confessed to occurred in Texas and Michigan; he had been implicated in at least 20 more murders. Law enforcement officials in Michigan, Texas, and Canada suspected Watts of slaying dozens of other women from the 1970s until his conviction in 1982. Watts had told officials that he would kill again if he ever got out of prison. Michigan and Texas officials opened cold cases to further investigate Watts for his earlier crimes, because he had already received immunity for the ones he had confessed to in 1982. In Michigan, police had suspected Watts for years of the murder of Helen Dutcher but never had the evidence to charge him. They reopened the case, finding a previous witness. Joseph Foy had come forward at the time of the murder, saying that he had seen Watts murder Dutcher in his suburban backyard in 1979. Foy had reported the crime and described in detail the appearance of the perpetrator. A police sketch artist had made a drawing from Foy’s description. Watts was brought to trial in Michigan in 2004. Three former victims Watts, 1979 Police sketch who had survived attacks by Watts, as well as the detectives who took Watts’s past confessions, testified at the trial. All testimony was allowed as evidence of a “pattern” of Watts’s past behavior. At the trial, the defense asked whether a witness could identify someone 85 feet away on a darkened night and whether Foy’s memory would be accurate after 25 years. The court allowed the eyewitness testimony to be submitted. The jury found Watts guilty of the first-degree murder of Helen Dutcher. In December of 2004, he was sentenced to life in prison in Michigan. Law enforcement officials continue to investigate Watts, who claimed he was responsible for at least 80 other murders from the 1970s until his conviction in 1982. 2.2: Ronald Cotton Ronald Cotton was wrongfully accused and convicted of a crime he did not commit, based partially on an eyewitness account that later proved to be inaccurate. In July of 1984 an assailant broke into two apartments on separate occasions in Burlington, North Carolina. He cut phone wires, attacked and raped the women living there, searched through their belongings, and stole money. After 38 Chapter 2 kh00116_CH02.indd Page Sec1:39 7/17/08 4:12:41 PM elhi-8 /Volumes/110/KHUS021/indd%0/Ch 02 a photo identification by one of the victims, Ronald Cotton was arrested for the crimes. The prosecutor’s evidence consisted of: Testimony by the other victim from a lineup A flashlight found in Cotton’s home that resembled one the assailant used Rubber from Cotton’s tennis shoe that was found to be consistent with rubber found at the crime scene The photo ID from the victim It was not disclosed at the trial, but the second victim had picked another man out of the lineup. Cotton’s attorney filed an appeal Cotton Police sketch based on this information. At the second trial, the second victim had decided that Cotton was indeed the assailant. Also during the second trial, a prison inmate, Bobby Poole, confessed to fellow inmates that he was the one who had committed the crimes. The judge refused to have this information submitted into evidence. At the conclusion of the second trial in November 1987, Cotton was convicted of both rapes and sentenced to life plus 54 years in prison. Cotton continued to claim that he was innocent and repeatedly asked for appeals. In 1994, Cotton got two new lawyers who filed a motion for DNA testing. The evidence samples from one of the Poole victims were too degraded and did not give any information, but samples from the other were intact enough to be tested. The samples did not match Cotton, and so he was ruled out as the perpetrator. At the request of the defense, the DNA was submitted to the North Carolina convicted violent felon database; it matched that of the inmate Bobby Poole. Cotton was released in 1995 after having spent almost 11 years in prison for a crime he did not commit. He was officially cleared of all charges and offered $5,000 as compensation. Jennifer Thompson, one of the witnesses, deeply regretted her mistake. She has since devoted her time to speaking out about her experiences and the dangers of relying on a single eyewitness account for evidence to convict. She has also become an outspoken activist opposing the death penalty. The Innocence Project is a national organization dedicated to exonerating wrongfully convicted people through DNA evidence. Eyewitness misidentification is the single greatest cause of wrongful convictions nationwide, playing a role in 75 percent of convictions that are overturned through DNA testing, according to the Innocence Project. As of January 2008, the project has exonerated 212 people from 31 states who have served a total of nearly 2,500 years in prison. Types of Evidence 39 kh00116_CH02.indd Page Sec1:40 7/17/08 4:12:44 PM elhi-8 /Volumes/110/KHUS021/indd%0/Ch 02 Not all evidence is permanent. For example, transient evidence is temporary; it is easily changed or lost. It is usually observed by the first officer on the Classroom Activity scene and must be recorded at that time. Examples of transient evidence are: Another fun activity is to have the class break up into groups odors such as perfume, purification, gasoline, cigarette smoke of three to five students and perform a crime skit. The skits temperature of a coffee pot, car hood, dead body, or water in a bathtub should be about five minutes long imprints and indentations such as footprints in sand, fingerprints in and include a crime, a setting, a dust, teeth marks in perishable foods victim, a perpetrator, and dialogue. An example may be: Two students Conditional evidence is produced by a specific action or event at the scene are on their way to a football game, walking while discussing a and must also be observed and recorded. Are the lights on or off? Is the movie they saw the night before. A garage door up or down? Are doors open or closed? Are windows locked or third student confronts them and unlocked? What is the position of the body and the furniture? asks to borrow a dollar. As one student brings out her wallet, the Some evidence does not prove a fact and is called indirect evidence. third grabs it and runs away. Some physical evidence, however, may prove something, such as One class period possession of a controlled substance or driving may be spent indirect evidence: evidence under the influence when a driver’s blood has writing the skits, providing only a basis for inference assigning roles, an alcohol level greater than 0.08 percent. about the disputed fact Circumstantial evidence implies a fact or event gathering props, and rehearsing and circumstantial without actually proving it. The more circumstantial timing the skits. At evidence: evidence based on evidence there is, the greater weight it carries. the next class, ask suggestion rather than personal students to clear Probability and statistics come into play here. For knowledge or observation example, suppose a blond hair is found in the hand their desks and simply “witness” the of a murder victim with black hair. The hair evidence crime is circumstantial because there are many people with blond skits. GO TO www.scilinks.org Later hair. If the footprint of a size-eleven sneaker is found near TOPIC circumstantial that hour evidence the victim as well, that is also circumstantial evidence—many or, better CODE forensics2E40 people have big feet and wear sneakers. However, the two yet, the observations together limit the pool of suspects. next day, ask students to answer the following questions about each skit: What Is the Value of Physical Evidence? Where did the crime take place? Physical evidence is valuable for several reasons: Describe the (imaginary) setting. Physical evidence can prove that a crime has been Examples of strange evidence Describe the victim. examined by author (J.F.): committed and set the scene for the investigation; What was he or she for example, gasoline found at the scene of a fire chicken cacciatore wearing? (poison case) may prove arson. Describe the sparkler (product liability) Physical evidence can back up witness testimony perpetrator. What was he or she itching powder or prove it false; for example, a forensic scientist wearing? beer (harmful contaminants) can test a bloodstain that a suspect claims is his Re-create any stepladder (personal injury) own and not the victim’s. dialogue that you sparks from static Physical evidence can link a suspect with a victim remember. electricity (fire) or with a crime scene; for example, a broken piece 40 Chapter 2 kh00116_CH02.indd Page Sec1:41 7/17/08 4:12:45 PM elhi-8 /Volumes/110/KHUS021/indd%0/Ch 02 Classroom Activity, continued Describe any other participants. Give any other information related to the crime. A class discussion can follow, noting which scenes were most memorable and why. If a weapon was involved, did it influence the witness? If some groups have more participants, was it easier to remember details or more difficult? If any of the groups turned the lights off, how did that affect the details remembered? This will help students to better understand the factors influencing the eyewitness accounts discussed in this section. Officer checking for possible stolen vehicle of headlight glass found in the cuff of a Perhaps the earliest recorded analysis suspect’s pants could place him at the scene of of physical evidence took place when a hit-and-run accident. Archimedes (287–212 BC) was consulted by the Greek king, who suspected that Physical evidence can determine the identity some of his wealth was made of an alloy of people associated with a crime; for example, rather than pure gold. fingerprints, handwriting, or DNA might prove that a certain person was present at a crime scene. Physical evidence can allow investigators to reconstruct a crime; for example, blood spatter patterns may show where the suspect and victim were located relative to each other and may indicate what happened and in what order. Police or crime scene investigators may collect questioned or unknown physical evidence and submit it to the lab for testing sample: material that has been by forensic scientists. The major role of the forensic collected from a known location but scientist is to determine if there are links among is of unknown origin the evidence, the victim, the crime scene, and the known sample: material suspect. The physical and chemical characteristics that comes from a proven or known of a substance or object may be identified, but it source is most important to see whether the evidence collected is relevant to the crime. Most often, a questioned or unknown sample (Q) is compared to a known sample (K). For example, the investigator finds paint of unknown origin on the bumper of a vehicle that is suspected to have been involved in a hit-and-run accident; it would Types of Evidence 41 kh00116_CH02.indd Page Sec1:42 7/17/08 4:12:46 PM elhi-8 /Volumes/110/KHUS021/indd%0/Ch 02 be compared to the paint from the victim’s bicycle (known origin). A control sample generally refers to a material that is expected to respond in a particular way in testing. It is used to validate the method of testing by comparing test results to those of the questioned and known samples. In the above case, suppose no color change could be induced by heating hundreds of different paint samples, yet when the Q and K samples were heated, both changed to the same color. A control test of one or more similar paints should be run in order to verify the method and procedure. If the control paints did not change color, but the Q and K samples did, then there is a high probability that the Q and K paint samples originated from the same source; therefore, the car was involved in the hit and run. The forensic scientist may then be part of a team using the physical evidence to reconstruct a crime. The team may include crime scene investigators, detectives or other law enforcement officials, medical examiners, and forensic Document examiner using Electrostatic Detection scientists. In a murder investigation, the physical evidence Apparatus to develop written impressions may be used to answer questions about what happened, how the victim was killed, whether there control sample: material was more than one person involved, and when that is similar to the questioned and known samples, and is used the crime happened. The reconstruction uses the to validate the test method and physical evidence as well as witness accounts and procedure statements by those involved in the case. Significance of Physical Evidence: Individual versus Class Evidence The best evidence is anything that can be linked to a unique, single, specific source. This is called individual evidence. Examples are fingerprints, handwriting, DNA patterns, and individual evidence: sometimes physical matches, such as a piece of material that can be related to a single source; individualization broken glass that fits exactly to another, like a always involves a comparison jigsaw puzzle piece. Unfortunately, most evidence is class evidence; this means that the object class evidence: material that can be associated only with a group has characteristics common to a group of similar of items that share properties or objects, but not to one single object. Take blue characteristics jeans, for example: Although we can go to some length toward individualization by classifying them by maker, model, size, color shade, and surface treatment, there are still thousands of other pairs of jeans that are just the same. However, that need not be the end of it: If the jeans have been worn, they might have tears, stains, or even creases that individualize them. 42 Chapter 2 kh00116_CH02.indd Page Sec1:43 7/17/08 4:12:47 PM elhi-8 /Volumes/110/KHUS021/indd%0/Ch 02 Probability and Class Evidence Activity 2.1 A young person was seen leaving a high school parking lot after having Procedure Notes been near a car with a broken window; the car’s CD player was missing. The This activity can be done as suspect was identified as having light brown hair and wearing a white shirt, a whole class. Modify the blue jeans, and dark-colored athletic shoes. In a school of 1,600 students, numbers to reflect your class how common are these characteristics? and your school. Look around at your students and decide How many students would be expected to be wearing a white shirt on any what characteristics you want given day? Let’s say that in your class of 33 students, seven are wearing a to emphasize, for instance, Nike white shirt. How many students in the whole school are likely to be wearing a shoes, gray sweatshirt, blond white shirt? hair, or glasses. Ask the class if they feel they are representative 7 wearing a white shirt of the whole school. = 0.21, or 21 percent 33 students in class Next question: How many students is 21 percent of the whole student body? Procedure Notes 0.21 x 1,600 = 340 Have students list class characteristics that they could So if your class is representative of the whole school, then you would expect use to describe students in their 340 students to be wearing a white shirt today. Is this good evidence? Could school. Then determine how you do better? many such characteristics would be needed to narrow a suspect How many students would be wearing blue jeans? In your class, you count down to one or two students. 12 wearing blue jeans. Usually with four or five class characteristics, the number of 12 wearing blue jeans suspects can be narrowed down = 0.36, or 36 percent to one or two students in the 33 students in class whole school! Types of Evidence 43 kh00116_CH02.indd Page Sec1:44 7/17/08 4:12:49 PM elhi-8 /Volumes/110/KHUS021/indd%0/Ch 02 Activity 2.1, continued How many students in the school would be expected to be wearing blue jeans? 0.36 x 1,600 = 580 students Is this good evidence? Why not ask how many students in the school are likely to be wearing a white shirt and blue jeans? 0.21 x 0.36 = 0.076, or 7.6 percent Procedure Notes to Activity 2.2 Now multiply this by the number of Activity 2.2 serves to illustrate students in school: the distinction between class 0.076 x 1,600 = 120 students and individual evidence, and the circumstances whereby class We have narrowed the field quite a bit evidence may be individualized. by looking at just two general pieces of It is helpful to have class evidence. stereomicroscopes available for use when necessary. The Now determine how many students 12 activities described can be would be likely to have light brown hair. discussed in class. The teacher In your class you count five students can also collect material and set with light brown hair: up stations with different items for the students to examine and 5 with light brown hair assess. Examples could include: = 0.15, or 15 percent 33 students 1. A piece of twine or rope cut from its parent. (Class) How many students in school would be likely to have light brown hair? 2. Small glass fragments 0.15 x 1,600 = 240 students compared to a large bottom How many students would be likely to be wearing a white shirt and blue or top section of a bottle (so they cannot be fitted jeans and to have light brown hair? together). (Class) 0.21 x 0.36 x 0.15 x 1,600 = 0.011, or 1.1 percent 3. A bank robbery note and the pad it came from. (Class, So to determine how many students in the whole student body meet all those unless the tear pattern can descriptors: be matched or indented 0.011 x 1,600 = 18 students writing recognized) 4. Three or more soda pop Statistically, you have narrowed the field of 1,600 possible suspects to just tabs compared to an empty 18. Now let’s calculate how four pieces of class evidence could affect the can without the tab. (Class, probability of nailing the suspect. If four students in your class are wearing probably) dark-colored athletic shoes, then: 5. A piece of paper, one of four 4 with dark-colored athletic shoes carefully cut from a single = 0.12, or 12 percent piece and compared to the 33 students others. (Class, probably) How many students in school would be likely to be wearing dark-colored 6. As above, but tear the athletic shoes? pieces and compare. (Individual) 0.012 x 1,600 = 190 students 7. A section of newspaper compared to the other sections. (Class) 44 Chapter 2 kh00116_CH02.indd Page Sec1:45 7/17/08 4:12:50 PM elhi-8 /Volumes/110/KHUS021/indd%0/Ch 02 Activity 2.1, continued Procedure Notes, continued 8. Cut a piece of duct tape and compare it to the How many students in school are likely to be wearing a white shirt and parent roll (and/or a blue jeans, and to have light brown hair, and to be wearing dark-colored different roll), or tear off a athletic shoes? piece. (Probably class if cut; individual if torn) 0.21 x 0.36 x 0.15 x 0.12 x 1,600 = 2 students! 9. Pull a few strands of yarn A way to increase the probative value of class evidence is to find as many from a sweater or fabric and different types of objects as possible with which to link the suspect to the compare them to the parent crime or the victim. (Probative means supplying proof or evidence.) So, (if not obviously damaged) or a similar item. (Class) soil and red paint on the jeans would each alone belong to a large class of 10. Enlarge an inked fingerprint material; but both occurring together might greatly increase the probability and compare it to several of linking those jeans with a certain crime, even though the evidence is other prints. (Individual) still circumstantial. 11. Break a hefty stick in two. You can see how the probative Dab some “blood” on the value continues to grow by simply one from the assault scene and compare it with the considering class evidence. This type other end that was found of statistical analysis is termed “the in the suspect’s woodpile. product rule,” and it works only for (Class, unless the break can independent events or observations. be fitted together) For example, if students were 12. Tear a page from a book encouraged to wear the school colors and crumple it up; place of blue and white, then wearing blue the closed book beside it. (Individual) jeans and a white shirt would be related and not independent. Your imagination is the limit in setting this up. The local Is class evidence useful? Yes, if junkyard may be a good place there is a significant amount for to visit and collect a number of a given case. It is also very useful samples to use in class. in eliminating or exonerating Using stereomicroscopes certain suspects. For example, if a can be fun for the students. bloodstain is found to be type O, the Most students have used a microscope before but haven’t most common type, people with type O.J. Simpson had time to explore and enjoy A, B, or AB can all be eliminated as the wonders of the microworld. possibilities. Give them some time to look at In the preliminary hearings of the O. J. Simpson case, the prosecution their fingernails, scars, jewelry, a piece of clothing, and the gave evidence that blood found at the crime scene had been tested by like. The objective is to allow conventional blood grouping methods and matched Simpson’s blood. One students time to discover how in 400 people share these blood characteristics. The defense argued that the stereomicroscope works. By given the population of Los Angeles, this number of people would fill an the end of the year, students will entire football stadium; therefore, the blood evidence was useless. Is this know which type of microscope true? If the blood evidence were the only evidence the prosecution had had, (compound or low-power stereo), which type of lighting the reasoning may have been correct. But if there were other types of class (transmitted, reflected, or both), evidence implicating Simpson, should the significance of the blood evidence and what magnification to use have been considered? for optimum results in various In the next activity, you will examine the concepts of class and individual situations. The microscope is the forensic scientist’s best friend. evidence with a series of comparisons. Types of Evidence 45 kh00116_CH02.indd Page Sec1:46 7/17/08 4:12:50 PM elhi-8 /Volumes/110/KHUS021/indd%0/Ch 02 Activity 2.2 Can This Evidence Be Individualized? Answers 1. A torn T-shirt was found in the backseat of 1. Tear a piece of cloth from a a suspect’s car. A piece of torn cloth was T-shirt. Set the piece out with found at the scene of the crime. Can it be the shirt and add another individualized to the T-shirt? Explain. piece of the same color and type of fabric from a different source. Students should be able to individualize one piece, while identifying the other as class evidence. 2. A pistol was found in a theatre where a man Ask them whether the color was shot. A suspect known to have owned makes a difference. White a Derringer like this one was apprehended. is a more common color for a T-shirt, so a red shirt, Would this gun be considered individual or for example, would have class evidence? more probative value. Even better than color would be a 3. Pieces of a broken bottle were found at matching imprint. the scene of an assault. The bottom of a 2. The gun is class evidence bottle was found in a suspect’s car. Can the unless it was one of a kind pieces of the bottle be uniquely associated and specifically linked to its owner (who happened to be, (individualized) with what was found in the say, John Wilkes Booth). suspect’s car? Explain. 3. Break a bottle so that the pieces are large enough to 4. Some blond hairs were found on the gloves of fit together as individual a suspected kidnapper who has brown hair. evidence, like pieces in a Would they be considered class or individual jigsaw puzzle. Wrap the bottle evidence? in layers of newspaper before using a hammer or pipe. 4. Even if the victim had blond hair, the hair is class 5. A bloody knife has been found in the evidence. backyard of a murder suspect. Under what 5. Fingerprints on the handle circumstances could it be individualized? Or would specifically identify the will it remain class evidence? culprit. Blood analysis could tie it to the victim. 6. Millions of tires are manufactured with the same 6. Are tire impressions such as these individual imprint. What may make a tire or class evidence? Explain. unique is the wear pattern coupled with imperfections or damage (cuts, nails, pebbles in a groove, etc.). 46 Chapter 2 kh00116_CH02.indd Page Sec1:47 7/17/08 4:12:52 PM elhi-8 /Volumes/110/KHUS021/indd%0/Ch 02 Activity 2.2, continued Answers, continued 7. If you know a hunter, policeman, or proprietor of a 7. Can it be determined whether these bullets local shooting range, collect were fired from the same gun? How can several spent bullets and shell bullets be individualized to a gun? Explain. casings of the same caliber. Bullets can be individualized by striations on the outside, and spent shell casings can be individualized, to some degree, by the firing pin marks. 8. Use baking soda or some other powder; place some 8. Some powder was found in a plastic bag in a in a baggie and another suspect’s pocket. Some similar powder was sample in a vial. Even found on the victim. Can the first powder be though the two samples individualized to the second powder? Explain. are the same powder If the two powders were determined to be chemically, there is nothing chemically identical, does that prove they unusual about them, and there is no way to prove that came from the same source? the powder in the vial came from the same source as the powder in the bag. It is, 9. A pair of latex gloves was found at the scene therefore, class evidence. of a robbery. A box of the same brand of latex 9. Take two latex gloves out of gloves was found at a suspect’s home. Can the a box and set them next to gloves be individualized to the box? Explain. the box. There is no way to individualize the gloves to that particular box. 10. No, because it could have 10. A cigarette butt was found at the scene of a come from any cigarette crime. Is it individual evidence? Explain. package 11. Without the matchbook, the single match is class evidence. But by comparing the match’s characteristics (such as dimensions, color, head, composition, tear 11. A match was found at the scene of a pattern, and the like) with suspicious house fire. A suspect was found those from the suspect’s carrying a book of matches, several of which matchbook and perhaps a dozen randomly collected were missing. Is the single match class or matchbooks, it could be individual evidence? Explain. individualized. This is a good experiment to do with the stereomicroscope. Types of Evidence 47 kh00116_CH02.indd Page Sec1:48 7/17/08 4:12:53 PM elhi-8 /Volumes/110/KHUS021/indd%0/Ch 02 Answers, continued Activity 2.2, continued 12. Soil composition and characteristics vary considerably, even in small 12. A suspect in a B & E (breaking and entering) areas. If everything matched had shoes that were caked with soil. Is the and it could be shown that soil class evidence, or could it be considered there were no other similar individual evidence? Explain. samples wherever the suspect had been, perhaps it could be individualized enough to provide strong evidence. Better would be a matched impression with a shoe print from the scene. That would put the suspect there, but not necessarily in the house. 2.3: Fracture Match A note was found by a student in the math lab at a community college. It was written in blue ballpoint ink on a piece of lined paper torn from a spiral notebook; it stated that there was a bomb hidden in the building. The student quickly turned the note over to the authorities, who evacuated the building. It being a pleasant summer evening, a lot of students hung around waiting for the bomb squad. A campus police officer walking through the crowd noted a student with a math book and a spiral notebook. On a whim, the officer struck up a conversation with the student and asked if she might look at the student’s notebook. The notes and equations before the blank pages were written in blue ballpoint ink, and at least one page had been torn out, leaving scraps of paper stuck behind the spirals. The officer felt that this was enough cause for her to seize the notebook as evidence. Later, at the crime lab, a comparison of all the scraps of paper caught in the spirals yielded one that matched the bomb threat note. This is an illustration of individual evidence. By matching up the tear pattern, it could be seen that the note came from the student’s notebook and no other notebook but hers. The combination of a lucky set of circumstances and an astute officer caught the culprit. Oh, there was no bomb—the student was bored and hated math. Matching pattern 48 Chapter 2 kh00116_CH02.indd Page Sec1:49 7/23/08 4:19:55 AM elhi-8 /Volumes/110/KHUS021/indd%0/Ch 02 2.4: Richard Crafts Richard Crafts was convicted of the murder of his wife, Helle, in 1986. It was one of the first cases where a person was convicted of murder without a body to prove that the crime had taken place. The case was built on forensic evidence and astute investigative work. Richard and Helle had had a tumultuous marriage, with accusations of infidelity on both sides. Helle had filed papers for divorce. November 18, 1986, was the last time Helle was seen or heard from. Her family and friends became alarmed; she had told one of them, “If anything happens to me, don’t think it was an accident.” This spurred her friends to encourage the police to investigate Richard as her possible murderer. The investigation turned up several interesting points. The nanny had found a stain on the master bedroom carpet, which Richard had replaced on November 22. Police discovered that Richard had purchased new bedding and a freezer and rented a wood chipper days before Helle disappeared. When a truck driver came forward and told police that he had seen someone chipping something into the Richard Crafts at trial Housatonic River in the middle of the night during a snowstorm, police began to piece together the events that led to Helle’s death. Investigators went to the river where the truck driver had seen the wood chipper and began to search for evidence. They found a chain saw from which someone had attempted to file off the serial number; the serial number had been warranted to Richard Crafts. Human tissue, hair, and a blue fiber matching Helle’s robe were found embedded in the teeth of the chain saw. Searchers also found 2,660 strands of hair, 59 slivers of human bone, two tooth caps, five droplets of blood, two fingernails, Wood chipper part of a finger, and three ounces of human tissue. Here is a case where thousands of hours Investigators pieced together a scenario: Richard killed Helle in were also expended to bring a killer to their bedroom with some sort of blunt object, leaving bloodstains justice. What often is not stressed is the on the carpet, bedding, and the towels used to clean up. He then amount of “old-fashioned” police work put her body in a freezer to make it easier to dismember her with involved in following leads, interviewing, the chain saw. He rented a wood chipper to dispose of her body and writing reports, all culminating in time spent in court at the trial. Note in completely in the Housatonic River, and then disassembled the two of the four Case Studies presented chain saw and threw it into the river. in this chapter how lucky coincidences After literally thousands of forensic tests, the tissue evidence was led to the perpetrator. What were they? found to be consistent with Helle, and some was even determined to be positively Helle’s. Even though the amount of evidence was not much, Answer estimated to be roughly one one-thousandth of a human body, it was enough (1) An astute policewoman noting the to provide material for more than fifty thousand forensic tests. Without forensic spiral notebook and investigating; science, it is doubtful that Richard Crafts would have been convicted and (2) A truck driver happened to be at the right place at the right time to sentenced to 50 years of imprisonment for the murder of Helle Crafts. observe the use of a wood chipper in the dead of night. Types of Evidence 49 kh00116_CH02.indd Page Sec1:50 7/17/08 4:12:59 PM elhi-8 /Volumes/110/KHUS021/indd%0/Ch 02 Answers Checkpoint Questions 1. Testimonial evidence is what is said in court by a competent witness. Physical evidence consists Answer the following questions. Keep the answers in your of tangible items that tend to prove some material fact. notebook, to be turned in to your teacher at the end of 2. Possible factors are the nature of the offense the unit. and situation, the age of the witness, the length of time between the offense and the testimony, interviewing techniques, the witness’s prior 1. Explain the difference between testimonial evidence relationship with the accused, and any earlier and physical evidence. identification of other suspects by the witness. 3. any material or object that can be related to the crime, including hair, blood, fibers, poisons, 2. List three factors that may affect the memory of an fingerprints, soil, glass, and drugs (see Table 2.1 eyewitness in recounting a crime. on page 37) 4. Circumstantial evidence implies a fact or event but does not prove it, while physical evidence may prove a fact. Physical evidence is specifically 3. List five types of physical evidence. relevant to the crime. 5. Some examples may be odors that evaporate, temperatures that cool, or prints that blow away in 4. How is circumstantial evidence different from the wind or are obliterated by rain. physical evidence? 6. Examples may be: A body may be moved, the lights may be switched off, the windows may be closed. It is conditional because it is caused by an event or condition at the scene. 5. Give three examples of transient evidence and 7. Physical evidence is generally more reliable due to explain why it may be transient. the fallibility of eyewitness accounts. 8. evidence that does not necessarily prove a fact but implies a fact or provides a basis for its inference 6. Give three examples of conditional evidence and 9. eyewitness accounts explain why it is conditional. 10. He was scheduled to get out of prison, and they knew he was responsible for many more crimes. They did not want him to get out and 7. Which is generally more reliable, physical evidence commit more. or testimonial evidence? 8. What is meant by indirect evidence? 9. What significant type of evidence was used to convict Coral Eugene Watts? 10. Why did prosecutors want to reopen his case after so many years? 50 Chapter 2 kh00116_CH02.indd Page Sec1:51 7/17/08 4:12:59 PM elhi-8 /Volumes/110/KHUS021/indd%0/Ch 02 Answers, continued 11. The case illustrates the fallibility of eyewitness accounts. 11. What is the significance of the Ronald Cotton case? 12. Individualized evidence has a common origin, while class evidence only shares common characteristics. 12. State the difference between class and individual 13. Class evidence cannot, but individual evidence. evidence can. 14. It can exonerate suspects who are from a different group. For example, if type A blood is left at a crime scene, people with types O, AB, and B may 13. Can class evidence be used to link a suspect be eliminated as the source. Class evidence with certainty to a victim or crime? Can individual may be useful when there are different types of evidence? evidence or there is a lot of it. 15. Also known as testimonial evidence, direct evidence is statements taken under oath, as in the case of an eyewitness account. 14. Explain how class evidence may be useful. 16. Evidence is collected from the crime scene, while controls are collected from the victim, suspects, or other known sources. 15. What is direct evidence? 17. It can prove that a crime has been committed; establish key elements of a crime; back up testimony or contradict it; link a suspect with a victim or crime scene; establish the identity 16. Where is physical evidence found and collected? of people associated with a crime; or allow reconstruction of the events of a crime. 18. In forensic science, a control sample is one whose 17. Why is physical evidence important? What can origin is known. It is collected from the victim it prove? or suspects for comparison with the unknown or questioned crime scene evidence. In a laboratory context, a control is often a sample used to test a method, and a standard is a known sample. 18. What is meant by a control sample? 19. The probabilities can be multiplied together to provide stronger evidence. 20. Individual evidence can prove something that is 19. How can class evidence be used to narrow a field material to a crime. Fingerprints are considered of suspects? to have high probative value because they can belong to only one person. 21. Class evidence does not generally prove a fact, except in cases where it exonerates or eliminates 20. Explain how individualized evidence can have individuals. probative value. 22. Student answers will vary, ranging from conviction for murder without a body to the extraordinary number of forensic tests. 21. Explain how class evidence can have probative value. 22. What is the significance of the Richard Crafts case? Types of Evidence 51 kh00116_CH02.indd Page Sec1:52 7/17/08 4:12:59 PM elhi-8 /Volumes/110/KHUS021/indd%0/Ch 02 Project: Both Sides of the Issue; Public Information on Registered Sex Offenders Suggested Assignment Recently, many states have passed statutes about community notification This is an optional project for whenever a sex offender is scheduled to be released from prison or moves students to research and present into a community. This brings up the question of which right should take both sides of an issue. Look for priority, the right of the individual to privacy or the right of society to students to be able to critically know (freedom of information). assess the merits of each side. This project may be interjected Write a paper analyzing the arguments on both sides of the issue at any point in the chapter. of registering sex offenders and publishing their names. So you can understand both sides of the issue and learn how to identify and defend the side you disagree with, structure your paper in the following way: TITLE: Should the names of registered sex offenders be available to the public? AUTHOR: Your name INTRODUCTION: Write one or two paragraphs briefly explaining how the names of registered sex offenders may be published, according to the law, and why the issue is controversial. PRO SIDE: Write one sentence stating that names of registered offenders should be published. SUPPORT: Write a short statement about society’s right to know. Write at least three paragraphs supporting the statement, using at least three sources. CON SIDE: Write one sentence stating that no list of registered sex offenders should be published. SUPPORT: Write a short statement explaining why the rights of the individual should take priority, especially regarding privacy. Write at least three paragraphs supporting the statement, using three sources. PERSONAL OPINION: Write your views and conclusions based on the arguments you have already presented. You must support one side or the other. WORKS CITED: List references for all sources you used. 52 Chapter 2 kh00116_CH02.indd Page Sec1:53 7/17/08 4:13:00 PM elhi-8 /Volumes/110/KHUS021/indd%0/Ch 02 Additional Projects 1. Can tabs from a soda pop can be matched to the parent can? To what degree? To a particular brand? To a particular can? How would you set up a research project to answer such questions? What characteristics of the tab and parent would you look at? Check with your teacher and carry out the project, using the scientific method of approach. 2. Suppose a hate note was written in fingernail polish on, say, a mirror or car window. Would it be possible to match the polish to its source? What characteristics of the polish could be used for the comparison? Set up a research project. 3. Glitter is becoming prevalent in many areas of our lives. If glitter were left at a scene of a crime, how might it be traced to its source? 4. Rope is often used in the course of a violent crime. What are the qualities of a rope that could be used to compare one piece with another? References Books and Articles Films Buckhout, R. “Eyewitness Testimony,” Scientific The List Murders can be ordered from www.films. American, 231 (June 1974), pp. 23–31. com/Home.aspx (identification of a murderer Evans, C. Casebook of Forensic Detection. New York: after 19 years). DVD, VHS. John Wiley, 1996. Ragle, Larry. Crime Scene. New York: Avon Books, 2002. Websites Saferstein, Richard. Criminalistics: An Introduction www.crf-usa.org/bria/brial33.html#how; eyewitness to Forensic Science, College Edition (9th ed.). reliability Englewood Cliffs, NJ: Prentice Hall, 2006. www.crimeandclues.com/testimony.htm; testimonial Siegel, Jay A. Forensic Science: The Basics. Boca evidence Raton, FL: CRC Press, 2007. www.pbs.org/wgbh/pages/frontline/shows/dna/ cotton/summary.html; excellent interactive site illustrating the difficulty in identifying people. Very detailed look at the Cotton-Poole case. Types of Evidence 53