\IHHIHHIWIIIHWIIHWWII“!WIIIIH‘IWWI ||||llllllllllllllllIllllllllllllllllllllllll?\llHlllUlllHi 3 1293 01834 59 LIBRARY Michigan State University This is to certify that the thesis entitled A Fiber Transfer Study presented by Addie Christina Thorsen has been accepted towards fulfillment of the requirements for MS; degreein Criminal Justice z/D/CP? 0-7639 MS U is an Affirmative Action/Equal Opportunity Institution 4v-_—_.- --. —\ —'—-V _ _ + v _"_‘o— ' -.— r—T ——.— -_'__ PLACE IN RETURN Box to remove this checkout from your record. TO AVOID FINE return on or before date due. MAY BE RECALLED with earlier due date if requested. DATE DUE DATE DUE DATE DUE ‘ W" ”32001 SE331294ZBOQ 1]” WWW“ A FIBER TRANSFER STUDY BY Addie Christina Thorsen A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Criminal Justice 1999 ABSTRACT A FIBER TRANSFER STUDY BY Addie Christina Thorsen A large scale fiber transfer study was completed at Michigan State University in conjunction with the Federal Bureau of Investigation Laboratory. Volunteers wearing sweaters treated with fluorescent dye mingled in a large crowd at an American Academy of Forensic Sciences meeting. Members of the crowd were asked to tape lift their clothing one hour after possible fiber transfer occurred. The tape lifts were examined using UV light, microscopy, and visible light microspectrophotometry for fibers. Zero matching fibers from the treated sweaters were found on any of the tape lifts taken from the crowd member’s clothing. In a separate study, the same tape lifts were searched for human and non-human hairs. Approximately 43% of the 224 tape lifts contained human or non-human hairs or both. ACKNOWLEDGMENTS I would like to thank my professor, Dr. Jay A. Siegel, who is not only a wonderful instructor, but also a role model and the most generous person I know. His support, ideas and encouragement have given me the inspiration and motivation to succeed in my graduate education. I would also like to thank Max Houck for his ideas and assistance in this project. I am forever grateful. Finally, I would be amiss if I did not mention my hard-working assistant, Christina McKee. Thanks to Christina, my microscope-weary eyes received an occasional break and the work was reviewed. Thanks for an amazing amount of volunteer hours! iii INTRODUCTION TABLE OF CONTENTS LITERATURE R Transfe Persist Mechanisms Involved in the Transfer of Fibers ................ The Sig Target METHODS RESULTS Fiber R Hair Re CONCLUSIONS AND DISCUSSION FUTURE FIBER APPENDIX A: APPENDIX B: APPENIDX C: REFERENCES EVIEW r of Fibers ence of Fibers nificance of Fiber Evidence Fiber Studies esults Summary sults Summary STUDIES TAPE LIFTING KIT TAPE LIFT AFTER FLUORESCENCE SCREENING AND MICROSCOPE COMPARISON COMPARISON PHOTOGRAPHS OF KNOWN SWEATER FIBERS AND TAPE LIFT FIBERS w 10 13 15 17 71 77 77 98 79 24 4O 41 44 I NTRODUCT I ON A large scale fiber transfer study was done by the forensic science program at Michigan State University in conjunction with the Federal Bureau of Investigation Laboratory. Over 200 tape lifts were searched for specific, target fibers. Four volunteers wearing sweaters composed of target fibers attended a large meeting. The volunteers mingled with hundreds of attendees with . intentions of transferring the known fibers. After an hour, meeting attendees tape lifted their clothing. The tape lifts were examined for known fibers. In this study, known fibers were introduced to a population and the population was later searched for the fibers. This study examines transfer and persistence of fibers with a moderately controlled setting. The results of this study bolster the significance of finding matching fibers on two objects. By the suggestion of a forensic hair examiner, a separate aspect of the tape lifts was studied. The tape lifts were searched for human and non-human hairs. This part of the study was an afterthought and is completely separate from the fiber study. The hair analysis was done to show the likelihood of finding hair evidence when tape lifting subjects. As a group, forensic scientists study many different types of evidence including hairs, fibers, explosives, soils, glass, and paint. Of these types of trace evidence, fibers are the most frequently encountered at a crime scene [5]. This is not terribly surprising considering how many objects in our daily lives contain fibers. The world is made up of various textile objects that shed and collect fibers including clothing, upholstery, and carpeting. With contact, fibers can easily be transferred from one person or object to another. According to the Locard Exchange Principle [13], contact between two objects always results in transfer of some material. For example, if a person sits in a chair, material from the person and from the chair are transferred to each other. Fibers from the person’s clothes may be left on the chair and perhaps dirt from the chair is transferred to the person's clothes. Whether the transferred material remains on the object or if it can be detected are other key issues. When properly analyzed, fiber evidence serves several purposes in criminal cases. Fiber evidence is often used to show contact between two persons if similar fibers are found on a victim and a suspect. Fiber evidence found on a suspect may be used to link the suspect to a crime scene or particular area. Fiber evidence can also be used to show a link between a suspect and a weapon. In a court of law, fiber evidence is commonly used to help prove that a suspect is guilty by showing a link between a crime and a suspect. Fiber evidence is often collected and may be very important in crimes involving close personal contact. Sexual offenses, assaults, and murder often involve transfer of fibers from the perpetrator to the victim and vice versa. Another event that may cause transfer of fibers is a hit and run accident; the victim may unknowingly leave fibers on the vehicle. A robber may also leave fiber evidence behind. Also in a court of law, the lack of fiber evidence could support a suspect’s innocence. If direct contact was suspected, yet no transferred fibers were found on either subject, then contact between the two may be questioned. In any case, fiber evidence collected at a crime scene in conjunction with fibers taken from a suspect or victim can be quite valuable. Although fiber evidence is common, it is often difficult to see without visual aids and can be overlooked when searching a crime scene. Before the evidence can be examined in the laboratory, it must be collected and stored properly. Searchers must be aware that fiber evidence is likely to be found, and thorough techniques must be employed. Methods of collection will vary depending on the scene and evidence collector. Some collection methods include an adhesive strip or roller called a tape lift, vacuuming for trace evidence, shaking the evidence over a collection chamber, and simply collecting a visible fiber with forceps. All fiber evidence should be packaged separately to prevent any cross-contamination. Moore et al.[12] studied the movement of fibers between examination working areas. The study showed that cross-contamination can be a problem and must be avoided by all means. For example, if a scientist working with a piece of clothing from one case does not clean their work area before starting a new case, the fibers from one case may be transferred to another case. This could lead to false data and conclusions. Once collected and submitted to the laboratory, fibers are analyzed by various techniques to determine if they could have come from a particular source. There are many techniques and instruments used to analyze fibers. A first test is a side by side visual comparison. The suspect and known fiber are microscopically compared for properties such as color and diameter. A cross section of the fiber may be studied. Polarizing microscopy can be used to classify fibers into groups, such as acrylic or nylon groups. Polarizing microscopy is a powerful technique that often can be used to confirm the exact type of fiber present. Visible light microspectrophotometry can be used to compare the colors of fibers by showing a fiber's absorption spectrum. Chromatographic methods can be used to determine fiber dye composition. Fiber comparison can also be done using an infrared spectrophotometer. A technique called Fourier transform infrared spectroscopy (FTIR) can be used to distinguish between two synthetic (manmade) fibers. In fiber analysis, the most challenging aspect may be determining the significance of evidence. Even if similar fibers are found on two objects, what does it mean? If similar fibers are not found, what does it mean? These questions must be addressed by the fiber analyst before writing a report with their conclusions. A large scale fiber transfer study is discussed along with relevant literature, results and conclusions. The results of the hair analysis are also discussed. L I TERATURE REVI EW In order to fully understand the relevance of the fiber transfer study, certain key aspects of fiber evidence must be discussed. These aspects include transfer (the shifting of a fiber from one object to another), persistence (how well the transferred fiber endures on another object), mechanisms involved in transfer, significance of fiber evidence, and target fiber studies. IransfemLEihers Pounds and Smalldon [17-19] were the first to publish fiber studies with significant results for the forensic science community. In 1975, they published three articles on fiber transference and persistence and the mechanisms involved. These studies were extremely important in the progress toward interpreting the significance of fiber evidence. In the studies mentioned, the focus was on wool and acrylic fibers, the most popular fibers at the time of the study [17]. The donor garments were two wool sweaters, which were treated with fluorescent dye and one hand- knitted, acrylic square, containing fluorescent dyes. The garments were pinned to a 14cm X 14cm polystyrene block. This block was pulled across the recipient garments (one acrylic sweater, one wool/nylon sweater, one cotton laboratory coat, and three wool jackets) with a constant pressure of either 30 or 300 kilograms per square meter. The recipient garments were on a laboratory bench when the block was dragged across causing fiber transfer. Their tests included repeated contact passes with the transferred fibers removed between each contact. The lengths of the transferred fibers were classified in four size ranges: 0.5-2mm, 2-Smm, S-IOmm and greater than 10mm. The results of their testing [1?] pointed toward several factors that affect the transfer and persistence of fibers. The factors they noted were the type of donor material, the type of recipient material, the amount of pressure applied during contact, the number of contact passes, and the length of the fibers being transferred. The nature and the size of the donor material greatly affected the amount of transferred fibers. Certain materials shed more fibers. Kidd and Robertson [9] conducted a study which showed that a donor garment’s fiber composition affected fiber transfer. The nature of the recipient material, including texture and fiber composition, also greatly affected the number of fibers transferred. Also, as the size of the donor garment increased, the number of transferred fibers increased. The amount of pressure applied had a correlation with the number of fibers transferred. For example, Pounds and Smalldon [17] found that increased pressure increased the number of fibers transferred. Kidd and Robertson [9] agreed with that finding but added a stipulation. Increased pressure will increase transfer until a maximum or threshold pressure is reached, and then no additional fibers will transfer. This threshold pressure may be different for various fibers. The number of contact passes increased the total number of transferred fibers up to a point until reverse transfer started occurring [17]. Fibers that a garment originally shed may be transferred back to it on repeated contact passes. With repeated passes the number of fibers transferred decreased [9], probably because fibers easily shed were gone. Finally, Pounds and Smalldon [17] found that fiber length combined with pressure affected transfer. Long fibers (greater than 10mm) transferred more at lower pressures. Also, the recipient material affected the length of fibers transferred. Cordiner, Stringer and Wilson [3] published an article in 1985 discussing the role of fiber diameter in transference. They found that fine fibers may be more likely to transfer than larger, coarse fibers. Since many textile fibers worn and used today are composed of two or more types of fibers, it is important to discuss transference versus composition. First of all, the description of a garment’s composition tag refers to the percent by weight of each component [15]. Therefore, the tag does not necessarily reflect the numerical distribution of the blended fibers. Salter et al. [21] also pointed out that fiber content of a mixed fiber article can differ greatly from the ratio of transferred fibers. Certain fibers have a greater tendency to transfer than others. Parybyk and Lokan [15] performed a study to determine the numerical distribution of transferred fibers when blended fabrics are involved. They found that wool containing blends tend to shed wool greater than other fibers. One reason for this finding may be that natural fibers normally fragment easier than manmade fibers, and the fragments are more likely to shed. Therefore, a garment blended with a high percentage of nylon and a small percentage of wool fibers may only shed wool fibers. In a case involving an article with blended fibers, it may be argued that there was no possible link to the accused if only one type of fiber was found; this study proves otherwise. Most fiber transfer studies examine primary transfer, in which a fiber is simply transferred from one object to another [23]. A secondary transfer occurs when that same fiber is transferred to another object. This continues on and on until the fiber is stationary. The fiber transfer study described in this paper is affected by primary and higher order transfers. Fibers may have been transferred from the sweaters to the attendees and then transferred to other attendees or other objects. Studies show that the number of fibers transferred to clothing via secondary transfer is much smaller than via primary transfer [6,11]. Still, fibers shed through primary, secondary, tertiary and higher order transfers could be collected by the tape lifts. E . E E'l Persistence of transferred fibers, or the likelihood of the fibers staying on a new object, is an important factor in forensic identification of fibers. With many crimes, a suspect is not arrested for several hours, days or even months. This greatly affects the likelihood of 10 finding trace evidence that may have been transferred during contact. There have been several studies on persistence of fibers. In 1975, Pounds and Smalldon [18] published a major study on persistence of fibers. This study was a continuation of their transfer study mentioned earlier [17]. Again, they used blocks to transfer the fibers from the squares to the recipients. The transferred fibers were then counted and the garments were worn. At set intervals, the garments were checked for remaining fibers. The authors found that the length of time the garment was worn was the most important factor in the persistence of the fibers [18]. They found no difference in the loss rate between the wool and acrylic fibers or fibers of different lengths. Fibers were lost at similar rates from recipient garments of different textures with slightly more rapid loss from smoother garments. In 1985, a study by Scott [22] on persistence of transferred carpet fibers confirmed that highly textured recipients hold fibers longer than smoother garments. Pounds and Smalldon [18] concluded that fibers are normally lost very rapidly within the first several hours of wear after transference. After four hours of wear, the 11 highest amount of fibers remaining was 18%, and after 34 hours of wear the highest amount remaining was 3%. In 1982, Robertson, Kidd, and Parkinson [20] published another study on persistence of fibers transferred during simulated contacts. The results of their study showed that the rate of fiber loss over time depends on many factors. These factors include: the garment being worn (increased loss), other garments being worn over the recipient garment (increased loss), the position where the transfer occurred, the pressure of the transfer contact (increased pressure decreased loss), and the size of the fiber transferred. This last factor differed from the results of Pounds and Smalldon [18], which stated that fiber length had little effect on fiber persistence. Robertson et a1. [20] found that longer fibers were lost more rapidly than fibers less than 2-5mm. Lowrie and Jackson [10] published a study in 1991 on recovery of transferred fibers. They also concluded that short fibers (less than 2mm) were the majority of fibers that persisted. However, they believe that shorter fibers make up the bulk of transferred fibers, so they could not conclude that short fibers persist longer. Lowrie and Jackson also concluded that the type of donor and recipient fibers involved in the transfer effected persistence. A 12 rougher textured recipient garment usually had more transferred fibers tightly bound to it, which made them harder to recover. Fibers can be removed more easily from smooth recipient surfaces, but the number of fibers persisting is lower. Lowrie and Jackson’s research also showed that within an eight hour period, less than 50% of the transferred fibers persisted. Persistence of fibers is greatly affected by wearing time. H l . I 1 1 . i I E E E'l In 1975, Pounds and Smalldon published a third part to their landmark fiber studies [19]. They investigated the mechanisms involved in transfer of fibers and subsequent persistence on garments. The authors showed that electrostatic interactions were not responsible for transfer; instead, they gave three mechanisms of fiber transference. First, fiber fragments existing on the surface of the donor garment can be easily exchanged at time of contact. Second, fibers may be loosely held in the yarn of the donor garment and can be pulled out by surface friction. Thirdly, direct contact between a donor and recipient may cause fragmentation of fibers, which then may be transferred. 13 As discussed earlier [18], persistence of fibers diminishes greatly after several hours. Therefore, the fibers remaining after several hours are likely to be tightly bound and may be hard to recover. With many crimes, a suspect is not apprehended and searched for hours or days, so only a few fibers may be remaining. To have a chance of collecting these few remaining fibers, a successful recovery method must be used. Pounds [16] listed several characteristics of an ideal searching technique. The technique should be highly efficient for removing transferred fibers; a low amount of background fibers should be collected; a sampling of certain areas of the garment should be completed; fibers should be easily removed and separately mounted; and the technique should be time efficient. The author [16] tested five methods for efficiency in collection of transferred fibers: nylon brushing, shaking, vacuuming, and high— and low- adhesive tape lifting. In this study, the most efficient method was high-adhesive tape lifting, next low—adhesive tape lifting, next brushing, next shaking, and finally vacuuming. Low- adhesive tape lifts and brushing were similar in efficiency (mid range), while vacuuming and shaking were extremely inefficient methods. 14 Tape lifting was also used in an experiment by Coxen et al. [2] to determine fiber shedding potential of garments. The adhesive tape lifts ripped fibers from the surface causing an overestimate of shedding potential. The authors recommended to use caution when using tape lifts to determine fiber shedding potential. 1:] '2" '5' EE'! E'i Once the evidence has been analyzed, determining the significance of the finding is the next step. There are a number of factors that strengthen and weaken the significance of fiber evidence including the possibility of errors. Although examiner errors are possible, another important type of error is an association error. Gaudette [4] describes an association error as one in which an unknown fiber is linked to a known sample; however, it could actually have another source. The author explains these errors generally occur because fibers are mass produced. Gaudette [4] describes two types of errors. A type I error occurs if an examiner states that an unknown fiber could not have originated from the known source, when the fiber actually did come from the known. This is also 15 called an incorrect exclusion or a false negative. A type II error occurs if an examiner states that the unknown fibers could have come from the known, when the fibers actually did not come from the known. This is also called an incorrect association or a false positive. Obviously, an incorrect association would be much more serious for someone facing criminal charges. It could imply an association when there may not be one. Gaudette [4] states that the probability of reaching a type II error is not yet known. However, he presents some basic facts that imply a small chance of a type II error: 1. There is mass production of textile fibers. 2. With the different possibilities of fibers (color, type, diameter, etc.), the chances of finding a very similar type are small. 3. Some fibers are more common than others. 4. A randomly chosen garment does not always have the most common fiber type on it. 5. If there are fibers on a garment, recent contact is likely. Gaudette [4] gives an excellent summary of factors that strengthen and weaken the significance of fiber evidence. Some of the strengthening factors include: finding several fibers that are similar to the known, 16 finding matching fibers of several different types, finding fibers with unordinary characteristics, and cross-transfer of fibers between two objects. Some of the weakening factors include: finding common types and colors of fibers, finding many non-matching fibers and only a few similar fibers, and any contamination errors. When determining the significance of fiber evidence, Grieve [7] points out many factors to keep in mind. Some factors include: known factors about the case, time elapsed before evidence collection, the number of types of matching fibers, the quantity of matching fibers and unknown factors like degree and pressure of contact. Resources including transfer studies, target fiber studies, and manufacture resources can also be utilized. I E°i S! 1' Once properly trained, a forensic scientist can determine if fibers found on a suspect are similar to those collected at a crime scene. The hardest part may be determining the significance of the evidence. Target fiber studies help the scientist by determining the likelihood of a certain fiber occurring in a random, usually large, population. Their purpose is to rule out the notion that finding matching fibers is coincidental. 17 In a target fiber study, analysts choose a specific fiber and then search for that fiber in a large group of recipient garments or objects. The recipients are normally tape lifted and fibers from the tape lifts are compared to the known, target fibers. The number of target fibers found are totaled and their importance is discussed. In 1986, Cook and Wilson [1] published an important study relevant to the significance of finding fibers in contact cases. They chose four garments that were quite common at the time. They became familiar with the fibers from the garments using microscopy and infrared spectroscopy, and the fiber dyes were examined using thin layer chromatography (TLC). They searched 335 items of clothing from completed case work from four forensic science laboratories in England. Possible matches were compared to the known fibers using microscopy, visible spectroscopy, and TLC. Matching fibers were found on only 10 of the items, with a maximum of 2 matching fibers found on any one article. The authors' conclusions bolstered the significance of fiber evidence. If two or more fibers found are matching, chances are it is not coincidental. They concluded that finding matching fibers is a strong indicator that contact 18 occurred. If cross transfer occurs, it is even more likely that contact occurred. Also in 1986, Jackson and Cook [8] published a target fiber study by looking for two types of common fibers in 108 vehicle front seats. They collected 8436 fibers and 45 of these were found to be indistinguishable from one of the known target fibers. The most on any seat was 13, and the most in any one vehicle was 20. Again, the authors concluded that if a large number of more than one type/color of matching fibers are found, then direct contact is likely. Another target fiber study involving car seats was done by Palmer and Chinherende in 1996 [14]. They also used movie theater seats along with car seats as recipient garments. They had two types of known fibers to search for: red acrylic and green cotton fibers from selected items. They tape lifted 67 random cinema seats and the front driver and passenger seats of 66 cars. Possible matching fibers were examined using white light comparison microscopy only. Three matching red fibers were found on the car seats and 14 on the cinema seats. Six matching green fibers were found on the car seats and none were found on the cinema seats. Of these “matching” fibers, more may have been eliminated using more complex scientific 19 techniques. Even without further testing, the results show that finding a target fiber on a random article is unlikely. 20 METHODS A large scale fiber transfer study was conducted at Michigan State University with assistance from the FBI Laboratory in Washington, D.C. Four gray sweaters, composed of 30% wool, 50% acrylic, and 20% rayon fibers, were treated with a fluorescent dye called fluorescene. Four volunteers (two male and two female) wore the sweaters at an American Academy of Forensic Sciences meeting in San Francisco, California, in 1998. The volunteers were told to mingle with the approximately 1000 meeting attendees. The four volunteers were simply told to mingle with the attendees as they normally would. No instructions were given to specifically try to transfer fibers from their sweaters. The meeting attendees were visiting outside a large meeting room awaiting the start of a plenary session. Some of the volunteers and attendees had direct contact via hugging. Casual contact also occurred as the volunteers walked and talked with the attendees. The Lynn Peavey Company donated 1500 tape lifting kits for the study. Approximately 800 of these kits were placed individually on chairs in an indoor meeting room. The tape lifting kits contained an adhesive strip (5” x 7”) with 21 backing, a plastic collection sheet (6” x 8.25”), tape lifting directions, and a brief explanation of the study. See Appendix A for a tape lifting kit example. Attendees of the meeting were asked to tape lift themselves according to the instructions given in the kit. This was done approximately one hour after the volunteers had mingled in the crowd. After completion of the tape lifting, attendees were asked to return the used tape lifts to a box when exiting. The tape lifts were then sent to the Forensic Science Laboratory at Michigan State University in East Lansing, Michigan, for analysis. The tape lifts were screened and placed into one of three categories: used-properly, used- improperly, and not used. Of the 800 kits available, 413 samples were returned. Of the 413 returned 224 were used properly, 183 were not used and 6 were used improperly. If the adhesive strip was not placed properly on the backing card it was considered used improperly. These samples were not able to be properly searched for fluorescent fibers and were not considered in the study. The properly used tape lifts were individually numbered from 1-224. One of the four known sweaters was viewed under an ultraviolet (UV) light to observe fluorescence. This sweater was also tape lifted using the 22 same type of tape lift. This tape lift was also viewed using UV light. The fibers from the sweater fluoresced under long wave UV light. Each tape lift was then examined for similar fluorescent fibers using the long wave UV light box. Fluorescent objects on each tape lift were circled for further analysis. The tape lifts were rechecked for fluorescent fibers and were kept in their individual bags. 158 of the tape lifts contained fluorescent objects. It is important to note that most acrylic fibers and some other fiber types fluoresce under UV light without fluorescent dyes. Next, tape lifts containing fluorescent objects were analyzed using a Fisher stereo microscope at 15X. All circled fluorescent objects were viewed under the microscope. Known fibers from the sweater were also viewed using the same microscope for comparison. All fluorescent objects, with no resemblance to the known fibers, were eliminated by simply marking an x through the circled object. The fluorescent objects similar in nature to the known fibers were rechecked under the stereo microscope. Only 12 tape lifts had fluorescent fibers that were visually similar to the known, dark gray fibers. See 23 Appendix B for an example of a tape lift after the fluorescence and visual screening. The tape lifts containing similar fibers were sent to Max Houck, a fiber expert at the FBI Laboratory in Washington, D.C. The “matching” fibers were removed from the tape lifts and mounted on slides in a clear, mounting medium called Permount. The fibers were compared to the known fibers using comparison microscopy. In this technique a side-by—side comparison is done by viewing the two samples with two separate comparison microscopes. These microscopes are combined into one unit, so when looking through the single binocular unit, half the field seen is the one object and the other half is the other object. The fibers that were found to be similar using comparison microscopy were then analyzed using a visible light microspectrophotometer. This instrument combines a computerized spectrophotometer, used to obtain absorption spectrum, and a microscope for viewing the object. This instrument is commonly used in fiber comparison. Two similar fibers can be analyzed microscopically for visual differences, while the spectrophotometer is used to show the wavelengths at which the fibers absorb in the visible light spectrum. Two fibers may look similar but may be distinguished by their absorption at different wavelengths. 24 The tape lifts and microscope slides containing fibers from the 12 tape lifts were returned to the MSU forensic science laboratory. The mounted fibers on the slides were viewed along with known sweater fibers using a comparison microscope at 40X. Some of the fibers were visually similar, while other were quite different. The wool fibers were the easiest to distinguish because they are natural fibers with a shingle like appearance. See Appendix C for comparison pictures between known fibers and those collected from the tape lifts. The mounted fibers were also viewed using a polarizing microscope. This instrument allows the viewer to detect polarizing light passing through fibers. Different fibers produce different, vivid colors when the polarized light is used. These color differences allow the fibers to be placed into classes. Of the 12 tape lifts with fluorescent gray fibers, most contained dark gray, wool fibers. The MSU forensic science laboratory does not have a visible light microspectrophotometer, so no further fiber testing was completed. A final part of the study was added by the suggestion of a forensic hair examiner when the fiber data was presented at a conference. Since the tape lifts were accessible, a separate study was completed involving hair. 25 Each tape lift was searched for human hairs and non—human hairs to access the likelihood of finding hair samples in a random tape-lifting. First, the tape lifts were viewed with no visual aids for obvious hairs. Then the lifts were viewed using a stereo microscope at 40X. All human and non-human hairs were circled on the tape lifts. The number of tape lifts containing human and non—human hairs was totaled. Wool fibers (sheep hair) were not counted as non- human hair; these hairs were counted as fibers only in this study. 26 RESULTS Of the 800 tape lifts deployed at the meeting, only 413 were returned. Of the 413, only 224 were used properly. Of the 224, 158 contained fluorescent objects. Of the 158, 12 contained fluorescent objects that were visually similar to the known, target fibers. Comparison microscopy and visible light microspectrophotometry were used to compare the known fibers to those from the remaining 12 tape lifts. Zero matching fibers were found on any of the tape lifts. Approximately 43% of the 224 tape lifts kits contained either human or animal hair or both. WW 0 800 tape lifts deployed 0 413 tape lifts returned (52% of 800) o 224 of the 413 used properly (54% of 413) 0 158 of 224 contained fluorescent objects (71% of 224) 0 12 of 158 contained objects that were visually similar to the fibers from the known, treated sweaters (8% of 158) 0 matching fibers found on any tape lift 27 W o 126 of the 224 tape lifts contained no hairs (56% of 224) 0 98 of the 224 tape lifts contained hair (44% of 224) o 20 of the 98 contained human and animal hairs (20% of 98) 0 14 of the 98 contained only animal hairs (14% of 98) 0 64 of the 98 contained only human hairs (65% of 98) 28 CONLCUS IONS AND DI SCUSSION Past research with target fiber studies show that the chances of finding a random fiber are low. This study was quite different than a target fiber study because the fibers were not random. Instead, known fibers were in immediate contact with the recipient garments. The study was biased so that the meeting attendees would have a definite chance of being in contact with the known fibers. Still, no fibers from the sweaters were found on any tape lift. It is assumed that known fibers were transferred from the sweaters to the meeting attendees. The sweaters contained 30% wool, which is a natural fiber known for its high shedding potential. The Locard Exchange Principle states that contact between two objects leads to the transfer of some material. Personal contact was made between the four volunteers and the meeting attendees, so transfer of fibers is expected. So, why were zero of the fibers found? Although it is a possibility, this study does not imply that no fibers from the four volunteers' sweaters were transferred. Fibers were most likely transferred, but they may have been lost before the attendees used the tape 29 lifts. Pounds’ and Smalldon’s study on persistence of fibers [18] showed that typically over 50% of fibers are lost within the first hour of transfer. The attendees were mingling and were likely to be transferring the known fibers to other guests or to the floor, chairs, etc. Considering the clothing of the guests, the amount of people at the meeting, and the time between transfer and collection, persistence of fibers will be low. With the large group, secondary transfer and fiber loss were likely. The attendees gathering for the meeting were dressed in suits and more formal attire. These suits, commonly made of polyester, rayon, silk or acrylic fibers, may have been smoothly textured causing lower transference and persistence of fibers. Rougher textured garments, such as a wool or cotton sweater, would be more likely to trap in transferred fibers and hold them longer. A roomful of casually dressed attendees may have resulted in finding more transferred fibers. Casual contact is not likely to result in the transfer of tremendous amounts of fibers. Close, personal contact, such as a sexual assault, is more likely to result in a greater number of transferred fibers. Greater pressure and longer contact time would increase the amount of fibers transferred and persistence time. 30 The type of crowd present was not considered; however, the gender distribution could have had a large effect on the outcome. Females are more likely than males to have more personal contact with other females via hugging, thus transferring more fibers. If the crowd was mostly made up of men, fiber transference may have been low. Although the meeting was composed of forensic scientists, not everyone had experience with the tape lifting kits. The kits were not especially easy to use. It is easy to tape the ends of the lifter together because of the high adhesive used. It is difficult to get the used adhesive lifter to lay smoothly on the backing sheet. This makes seeing some of the collected material in the less smooth parts difficult. Also, attendees may have only tape lifted parts of their clothing causing them to miss some transferred fibers. Perhaps, having trained tape lifters would have changed the results. This could have ensured maximum recovery and consistency. This study shows just how significant finding a persisting, transferred fiber is. The study shows that casual contact normally does not result in the transfer of many fibers. Direct, personal contact is more likely to lead to fiber transfer. This study was biased to help ensure fiber transfer and still no matching fibers were 31 found. Matching fibers found on two different objects imply recent, direct contact and should not be ruled coincidental. Nearly half of the tape lifts contained human or animal hair or both. The most human hairs found on any tape lift was 7. The most animal hairs found on any tape lift was 6. The source of the hair is unknown. It is unknown if the hairs were from the person who tape lifted themselves or if they were transferred from another person or another object. Like fibers, hairs are a common type of physical evidence encountered at a crime scene. This study shows that in a random tape lifting, hairs are commonly found. Also like fibers, hairs are transferred and their persistence depends on many factors. Nothing is known about the transfer of the particular hairs in this study. The hairs on the tape lift may have come from that specific person or they may have come from another person or object. Nothing is known as to the persistence of the human hairs; however, the persistence of animal hairs is quite telling. There were no animals present at the meeting and most guests were wearing formal attire. One would assume that the formal attire would not be exposed frequently to animals. Still, 34 of the 224 tape lifts contained animal 32 hairs. Although the known fibers did not persist, the hairs were in abundance. 33 FUTURE F I BER STUDI ES With the abundance of possible fiber evidence and the corresponding significance in a court of law, fiber studies are a great asset to the forensic science community. The studies will help explain the significance of finding or not finding fiber evidence. Target fiber studies are used to show the chance of finding a random fiber in a large population. These studies show a small chance of finding target fibers for various reasons. Fibers are mass produced, so the fiber varieties are endless. This makes the chances of finding a specific fiber low. These studies also show that finding an abundance of target fibers on a recipient garment is especially low. This bolsters the notion that finding several known fibers on garment indicates recent, direct contact with the known garment. More target fiber studies need to be done looking for different fiber types on different recipient garments. Some good recipient garments would be fabric covered chairs in school lecture rooms, in doctor or dental patient waiting rooms, and in banquet halls. Common and more rare fibers should also be considered for the target fibers. Carpet fibers are quite common and a study involving a 34 specific carpet fiber as the target fiber would be interesting and worthwhile to fiber examiners, who encounter carpet fibers frequently. More studies similar to the transfer study discussed should be completed. With the surprising result of zero matching fibers, similar studies are important. Donor garments with different shedding potentials should be considered. An all wool garment would have a high shedding potential, and the wool fibers are easy to identify with a microscope. The shedding potential of the garment should certainly be considered more thoroughly. A different setting with a more casually dressed population could lead to more transfer and persistence of the known fibers. A final improvement would be to employ trained tape lifters to improve collection consistency. 35 APPENDICES 36 APPENDIX A TAPE LIFTING KIT rm CE _ Evm NCE LIFmG KIT AWENTION: Open this A.A.F.S. test kit immediately! Provided as a courtesy to: The Forensic Science Program Michigan State University The Federal Bureau of Investigation Laboratory Division bv LYNN PEAUEV COMPANY Photocopy of outside baggy of tape lift with label. 37 Peavey Trace Evidence Kit This plastic bag contains a simple fiber tape lifting kit. It is part of a research project sponsored and conducted by the Forensic Science program at Michigan State University and FBI Laboratory. It is a large scale study of the rate and amount of fiber transfer among a large population. Prior to this plenary session, several volunteers wearing special sweaters circulated among the people outside this room, hOpefully shedding fibers from their sweaters to the clothing of the meeting atten- dees. We ask that you help with the study by collecting fibers from the front of your clothing using the kit in this plastic bag. The kit consists of a clear, plasric lifter and a thicker, stiffer plastic backing sheet. ' 1. Remove the protective sheet from the front of the Peavey lifter. This will expose the sticky surface of the lifter. 2. Tape lift the front of your clothes, covering as much of the fabric as you can. 3. Carefully attach the Peavey tape lift to the stiff, plastic backing sheet. The adhesive on the lifter will stick to the backing sheet. 4. Put the backing sheet and lifter back in this plastic Zipr-Top evidence bag and zip it closed. 5. Please deposit the bag in the box provided at the exit of this room after the plenary session. Your Participation In This Project Is Entirely Voluntary And Anonymous. In The Spirit Of The 50th Anniversary Of The American Academy Of Forensic Sciences, We Hope You Will Participate. Thank You For Your Cooperation. Photocopy of instructions found inside tape lift baggy. 38 PEEL THIS BACKING SHEET AT TAB comes AND DISCARD. nus. . WILL expose THE ADHESIVE LII-TING suamoe. .. 9., ._ . :2: 3.3g. sag... .fi MOUNT ADHESIVE 810! com 0” CLEAR BACKING. ONCE TRACE EVIDENCE 38 UFTED. Photocopy of adhesive lifter and backing card of tape lift. 39 APPENDIX B TAPE LIFT AFTER FLUORESCENCE SCREENING AND MICROSCOPE COMPARISON Photocopy of tape lift #84. The circles represent objects that fluoresced under long wave UV light. The circles are crossed out because the fibers were not similar to the known under a stereo microscope. 40 APPENDIX C COMPARISON PHOTOGRAPHS OF KNOWN SWEATER FIBERS AND TAPE LIFT FIBERS KNOWN FIBER (RIGHT) UNKNOWNQS) (LEFT) Photocopy of a photograph of a known, wool fiber from the sweater (right) and a fiber from tape lift #25 (left). The two fibers were dissimilar. 41 KNOWN FIBERS (LEFT) UNKNOWN