1 FORENSIC SCIENCE Trace Evidence

Did You Know? u The history of prescription drug-use by Henri Paul was determined by analysis of his hair. Paul was the driver of the car inwhich he, Dodi Fayed, & Princess Diana died on August 31,

3 Introduction Trace Evidence--any small pieces of material, man-made or naturally occurring Most common examples: Hair Fiber

4 Test Questions for Trace Evidence u What is it? u Is it man-made or natural? u What is its source? u How common is it? u Can it be identified to a single source?

5 Hair Human hair is one of the most frequently found pieces of evidence at the scene of a violent crime. It can provide a link between the criminal and the victim and the crime scene. Usually class evidence Even varies within a single person Found only in mammals

6 What can we determine from hair From hair one can determine: u Human or animal u Race (sometimes) u Origin (head, leg…) u Manner in which hair was removed u Treated hair u Drugs/toxins ingested

7 Hair and Skin

8 Outgrowth of the skin Hair =dead cells Coated in protein coating (keratin)on the outer layer. Hair grows out of the follicle (new cells push the old ones up and out

9 Hair Structure

10 Hair Cuticle Mosaic Pectinate Imbricate Petal Diamond petal Chevron The cuticle is the outermost layer of hair which is covered with scales. Scales also always point toward the tip of the hair. These scales differ between species of animals and are named based on their appearance. Some of these scales are variations of the same and include:

11 HUMAN SCALES In order to visualize the scales –paint fingernail polish on a slide –place a hair on the polish –lift off the hair and observe the scale imprints What pattern is seen in this slide?

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13 Cat Hair

14 Bat Hair

15 Scale Types MosaicChevron

16 Scale Types (cont) PectinateImbricate

17 Scale Types (cont) PetalDiamond Petal

18 Hair Cortex The cortex gives the hair its shape & color. It has two major characteristics : u Melanin--pigment granules that give hair its color u Cortical fusi--air spaces, usually found near the root but may be found throughout the hair shaft

19 The medulla is the hair core that is not always present. The medulla comes in different types, thickness, and patterns. u Continuous u Intermittent or interrupted u Fragmented u Absent--not present Hair Medulla

20 Hair Medulla Patterns Uniserial Multiserial Vacuolated Lattice Amorphous (without a distinct pattern)

21 HUMAN MEDULLA Human medulla may be continuous, fragmented or absent.

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23 RABBIT MEDULLA Rabbit medulla is different depending on the type (location on the rabbit) of hair. The one to the left is multiserial. The one to the right is a uniserial ladder and is found in guard hair.

24 Double Medulla

25 Medullary Index Determined by measuring the diameter of the medulla and dividing it by the diameter of the hair. Medullary Index for human hair is generally less than 1/3. For animal hair, it is usually greater than 1/2.

26 Medullary Index Medullas in animals sometimes exhibit patterned shapes (humans are usually cylindrical)

Did You Know? u All of the hair follicles in humans are formed when a fetus is five months old. 27

28 Hair Growth u Terminology u Anagen--hair that is growing u Catagen--hair at rest u Telogen--hair that is dying u Length mm per day or 1 centimeter per month; approximately one half inch per month

29 Hair Growth

30 How/When Did It Leave? TelogenAnagen

31 Ethnicity Asian BlackAsian White

32 Cross-Sections Caucasian African American Asian

33 Dyed Human Hair

34 DNA The hair shaft contains abundant mitochondrial DNA--inherited only from our mothers. It can be typed by comparing relatives if no DNA from the body is available. Only the root contains nuclear DNA.

35 DNA The hair shaft contains abundant mitochondrial DNA--inherited only from our mothers. It can be typed by comparing relatives if no DNA from the body is available. Process is more difficult & costly than using nuclear DNA. Only the root contains nuclear DNA.

36 Collection of Hair Evidence u Questioned hairs must be accompanied by an adequate number of control samples. –from victim –possible suspects –others who may have deposited hair at the scene u Control Sample –50 full-length hairs from all areas of scalp –24 full-length pubic hairs

37 Hair Comparison u Color u Length u Diameter u Distribution, shape and color intensity of pigments granules u Dyed hair has color in cuticle and cortex u Bleaching removes pigment and gives yellow tint u Scale types u Presence or absence of medulla u Medullary type u Medullary pattern u Medullary index

38 Hair Toxicology Advantages: –Easier to collect and store –Is externally available –Can provide information on the individual’s history of drug use. Collections must be taken from different locations on the body to get an accurate timeline.

39 HAIR TESTING Procedure u Collect an adequate sample, cut as closely to the scalp as possible. u Wash the hair to remove lipids, oils, cosmetics and any drugs adhering to it u Cut it into one centimeter sections u Place hair in a digesting solution u Screening test--antibodies are added to the hair that bind with the drugs. If this shows that drugs are present: u A confirmation test is done by gas chromatograph and then a mass spectrometer.

Did You Know? u You lose approximately 100 hairs from your head each day. These end up on your clothes, in your hairbrush, on furniture, & at the places you visit. 40

41 Buckling

42 Razor Cut

43 Egg Case

44 Lice

45 Porcupine Quill

46 Wow

More hair 47

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49 Hair Coloring u 75% of adult females say they color their hair (7% in 1950). u Most popular current color is red. u Permanent coloring requires chemicals to reach into the cortex (through the cuticle). There they react with the cuticle, changing the color and becoming too large to be washed from the hair. u Nasty chemicals involved (ammonia, hydrogen peroxide, etc). Damaged by “Perming”

50 Hair Split Ends Severely Damaged Hair - The continuing destruction of the cortex of a hair: the long parallel bundles of keratin have been exposed and can be seen clearly.

51 Hair

52 Knotting, associated with African hair A healthy hair, its cuticle intact, taken from a newborn baby Damaged cuticle, due to backcombing heavily sprayed hair A hair shattered after severe perm damage

53 Hair A micrograph of a hair shaft. Note the layered cuticle on the shaft and the bulb at the bottom

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55 Fiber Evidence NOTE: Fabric is the type of material and fibers are the “threads” that make up the fabric The use of fiber evidence in court cases is used many times to connect the suspect to the victim or to the crime scene. In the case of Wayne Williams, fibers were the entire case. Williams was convicted in 1982 based on carpet fibers that were found in his home, car and on several murder victims (product rule).

56 Classification Classified according to their origin: Natural u Vegetable u Animal or protein u Mineral Man-Made u Regenerated u Pure Synthetic

57 Vegetable or Plant Fibers u Cotton u Hemp u Linen (Flax) u Ramie u Sisal u Bamboo

58 -nylon.jpg Cotton Nylon

59 Protein Fibers u Wool--animal fiber coming most often from sheep but may be goat (mohair,cashmere), rabbit (angora), camel, mink, beaver u Silk--animal fiber that is spun by a silk worm to make its cocoon; fiber reflects light and has insulting properties Wool Fibers ( 400X )

60 Mineral Fibers u Asbestos--a natural fiber that was used in fire-resistant substances u Metallics (mylar)--a manufactured mineral fiber u Fiberglass--another manufactured mineral fiber

61 Cellulose Fibers u Rayon-- first man-made fiber; soft, lustrous, versatile fiber Cellulose esters-- cellulose is chemically altered to create an entirely new compound not found in nature. u Acetate-- less expensive, less polluting than rayon

62 Polymers Synthetic fibers are made of polymers which are long string of repeating chemical units. The word polymer means many (poly) units (mer). The repeating units of a polymer are called monomers. By varying the chemical structure of the monomers or by varying the way they are weaved together, polymers are created that have different properties. As a result of these differences, forensically they can be distinguished from one another.

63 Petroleum Plastics (Made from derivatives of petroleum, coal and natural gas) u Nylon--most durable man-made fabric; extremely light weight u Polyester--most widely used man-made fiber u Acrylic--provides warmth from a lightweight, soft and resilient fabric u Spandex--extreme elastic properties

64 Fabric Production Fabrics are composed of individual threads or yarns, made of fibers, that are knitted, woven, bonded, crocheted, felted, knotted or laminated. Most are either woven or knitted. The degree of stretch, absorbency, water repellence, softness and durability are all individual qualities of the different fabrics.

65 Woven Fabric Woven fabric are made by interlacing warp (lengthwise) and weft (filling) yarns. Warp run the length of the fabric and parallel to the selvage which is the edge of the fabric. Weft cross over and under the warp threads. Types include: u Plain u Twill u Satin

66 Woven Fabric PLAIN u Simplest and most common weave u Warp and weft pass under each other alternately u Create even patterns of 1/1 and 2/2 u Design resembles a checkerboard

67 Woven Fabric TWILL u Create by passing the warp yearn over one to three weft yearns before going under one u Makes a diagonal weave u Design resembles a stair steps u Denim is the most obvious example

68 Woven Fabric SATIN u The yarn interlacing is not uniform u Creates long floats u Interlacing weave passes over four or more yarns u Satin is the most obvious example

69 Knitted Fabric Knitted fabrics are made by interlocking loops into a specific arrangement. It may be one continuous thread or a combination. Either way, the yarn is formed into successive rows of loops and then drawn through another series of loops to make the fabric. Diagram:

70 Identification and Comparison of Fibers u Microscopic examination –Color--compositional differences in the dyes –Diameter –Fibers surface--delustering particles that may be added by manufacturers u Microspectrophotometer-- compares fiber colors through spectral patterns u Chromatography-- gives a more detailed analysis of the dye composition

71 Identification and Comparison of Fibers (cont.) u Polarizing microscope u can be used to determine the refractive indices of various fibers. The fiber is immersed in a fluid that has a comparable refractive index. The disappearance of the Becke line is observed under the microscope. u In addition, fibers will absorb infrared light in a characteristic pattern. This can be observed through the use of an infrared microspectrophotometer and a microscope.

72 Collection of Fiber Evidence u Bag clothing items individually in paper bags. Make sure that different items are not placed on the same surface before being bagged. u Make tape lifts of exposed skin areas of bodies and any inanimate objects u Removed fibers should be folded into a small sheet of paper and stored in a paper bag

73 Uniqueness Establishing Individual Characteristics u If there is only one source for the transfer material with a controlled environment where the contact took place u If there is a method available to characterize the material, such as applying DNA Otherwise, trace evidence would have only class characteristics.

Fiber analysis lab 74 u Must wear goggles

Fiber analysis lab Burn test results fiberBehavior in flame Behavior removed from flame OdorAsh or residue 75

Fiber analysis lab Chemical test fiberAcetoneHClSodium Hypochloric Acid 76