Unit 5 Hair and Fiber Analysis

Students will examine hair and fibers in relation to physical evidence.Unit 5 Hair and Fiber AnalysisUnit 5 VocabularyHair shaftHair cuticleHair cortexHair medullaCoronal scalesSpinous scalesImbricate scalesHair root Hair follicleAnagen phaseCatagen phaseTelogen phasePlain weaveTwill weaveSatin weave Knitted weaveSynthetic fiber

Obj 1A: Microscopic Structure of HairA. Shaft portion of hair above the surface of the skin, made up of three layers1. Cuticle clear outside covering of the shaft, made up of overlapping scales. There are three basic scale structures that make up the cuticle. Combinations and variations of these types are possible.Corona-crown-like, found in small rodents and bats, rarely in humansSpinous- petal-like, found in seals, cats, & some animals never humansImbricate-flattened, found in humans and animals

Cat4

Obj. 1A: Microscopic Structure of Hair2. Cortex made up of keratin molecules, the pigment that gives hair its color. 3. Medulla row of cells running along the center of the cortex which may appear dark or translucent depending on the presence of air, liquid, or pigment. Can be fragmentary, interrupted, continuous, or stacked. May not be visible in human hair. In animals, it is at least 1/3 of the diameter of the hair.

Medullary Index is the quickest way to determine a hairs origin in terms of human or non-human.Hair is 3-D & of a circular natureA circumference is the distance across a circleIf the circumference of the medulla is less than 1/3 (33%) the circumference of the entire shaft, then it is most likely of human origin.If the circumference of the medulla is greater than 1/3 (33%) of the circumference of the entire shaft, then it is most likely of animal origin.

Medualla diameter vs. total diameter = medullary indexMoose hair: medullary index is > 1/3

Moose Hair11

Pigment granulesObj. 1A: Microscopic Structure of HairB. Root portion of hair below the skin, embedded in the follicleC. Follicle tube like organ in the under layer of the dermis and is linked to the bodys blood supply1. Papilla indentation of follicle where blood vessels, nerves enter and exit2. Matrix area of cell division and hair growth

Obj. 1B: GENERAL BIOLOGICAL MAKE-UP OF HAIRA. Shapes of hair1. Round = Straight Hair2. Oval curly hair3. Crescent kinky hairB. Growth1. There are 3 stagesa. Anagen phase active phase, averaging three to five years for scalp, 30-45 days for other parts of the body, hair grows about 1 cm a month.b. Catagen phase- intermediate period of hair growth, lasting 2-3 weeks, outer sheath shrinks to the root forming club hair, 3% of all hair at any one timec. Telogen phase resting phase, 10-15% of all hair, lasts about 100 days for scalp and longer for other parts of the body, club hair fully formed.

Obj. 1B: General Function of HairC. Function1. Protectiona. guards the scalp from injury and sunlightb. eyebrows and eyelashes protect the eyec. hair in ears and nostrils keep out foreign objects2. Helps regulate body temperature3. Touch receptors associated with hair follicles

Obj. 1C: CHEMICAL ABSORPTIONA. Hair Root1. Materials that enter the body are transported to the hair root through the blood vessels and deposited into the cortex.2. Since hair grows slowly, drug use can be traced over longer periods of time compared to blood and urine.3. Analyzing lengths of hair can indicate continuous or infrequent use and can even be matched to an approximate time line.4. There has been some success in scientists identifying metal poisoning through the examination of the cortex

Obj. 1C: CHEMICAL ABSORPTIONB. Scalp oil1. Sometimes investigators can find traces of a persons environment in scalp oil. Examples smoke from crack cocaine or heavy metal industrial pollutants.2. False positives are possible if the person was present where there were environmental factors.

Obj. 1D. HAIR! Humans & animalsA. Human race differences risky to assign racial characteristics, but some generalizations can be made1. European Origina. Shaft diameter: moderate with minimal variation (mean diameter for human head hairs - 80um)b. Pigment granules: sparse to moderately dense with fairly even distributionc. Cross-sectional shape: oval2. African Origina. Shaft diameter: moderate to fine with considerable variationb. Pigment granules: densely distributed (hair shaft may be opaque) and arranged in prominent clumpsc. Shaft: prominent twist and curld. Cross-sectional shape: flattenedObj. 1D. HAIR! Humans & animals3. Asian Origina. Shaft diameter: coarse and usually with little or no variationb. Pigment granules: densely distributed and often arranged in large patchy areas or streaksc. Medulla: prominent (often broad and continuous)d. Cuticle: thicke. Cross-sectional shape: round

Obj. 1D. HAIR! Humans & animalsB. Root differences1. Mature hair bulblike shape with few if any pigment granules2. Mature hair pulled from scalp may have follicular tissue attached and may looked stretched and there may be pigment granules since the hair was still growing3. Animal roots generally spear shaped

Obj. 1D. HAIR! Humans & animalsC. Pigmentation differences between human and animals1. Human hairs are generally consistent in color and pigmentation throughout the length of the hair shaft, whereas animal hairs may exhibit radical color changes in a short distance, called banding. The distribution and density of pigment in animal hairs can also be identifiable features. The pigmentation of human hairs is evenly distributed, or slightly more dense toward the cuticle, whereas the pigmentation of animal hairs is more centrally distributed, and more dense toward the medulla.

HAIR SAMPLES FROM DIFFERENT HUMAN RACES AND ANIMALShttp://www.fbi.gov/hq/lab/fsc/backissu/july2004/research/2004_03_research02.htm(from basic structure to scale casts)http://www.fbi.gov/news/stories/2005/march/hair031605/?searchterm=hair

Obj. 2 A: IDENTIFY AND COMPARE NATURAL AND SYNTHETIC FIBERA. Microscopic Examination1. Natural fibers have variation in shape, twisting, edges which are not smooth or scale patterns (wool), etc.a. cotton flattened tubes, twisted and bentb. silk tubular, doesnt twist muchc. wool looks like animal hair, overlapping scalesd. Linen plant fiber2. Synthetic fiber smooth forms, uniform shapes along the entire strand. The shapes are produced by machines.

Most Common FibersNatural = cottonSynthetic = polyesterObj. 2A: IDENTIFY AND COMPARE NATURAL AND SYNTHETIC FIBERB. Chemical testing methods1. Most current fiber analysis, like paint, is done with a Fourier Transform Infrared Spectrometer (FTIR).

Obj. 2A: IDENTIFY AND COMPARE NATURAL AND SYNTHETIC FIBER2. Fibers can also be tested with the following:Burn tests: The way a fiber burns can indicate the fiber type. The smell released when burned (such as wool) or the way it burn completely or melts, etc. Thermal decomposition: this burn test uses the smoke produced to determine its origins. It uses red and blue litmus paper, as well as lead acetate filter paper.Acid tests, base tests, acetone tests: These tests are used to determine what type of fibers the warp and the wefts are made of. Different types of fibers may dissolve or turn colors in the presence of the different chemicals.

Obj. 2B: COMPARE AND CONTRAST COMMON FIBER WEAVE PATTERNSWoven fabrics are made by interlacing warp and weft yarns, forming threads and textiles.Plain simplest and most common, warp and weft pass under each other alternately, design resembles a checkerboardTwill pass the warp yarn over one to three weft yarns before going under one, makes a diagonal weave, design resembles stair steps, denim is a good exampleSatin yarn interlacing is not uniform, creates long floats, interlacing weave passes over four or more yarns, satin is a good exampleKnitted interlocking loops into a specific arrangement, may be one continuous thread or a combination, yarn is formed into successive rows of loops then drawn through another series of loops

Obj. 2C: PROCEDURES FOR COLLECTION AND ID OF HAIR AND FIBER EVIDENCERecovery of evidence should be the most direct but least intrusive techniqueBag clothing item individually in paper bags, make sure that different items are not placed on the same surface before being baggedMake tape lifts of exposed skin areas of bodies and any inanimate objectsRemoved fibers should be folded into a small sheet of paper and stored in a paper bag