Unit 5 Hair and Fiber Analysis

Students will examine hair and fibers in relation to physical evidence.Unit 5 Hair and Fiber AnalysisLabs in this Unit1. Hair: observations, casts, animal vs. human2. Fiber observations: weave patterns, etc.3. Fiber composition: Chemical composition of fibers, Forensics book pages 109-111.4. Lyle & Louise

Unit 5 VocabularyHair shaftHair cuticleHair cortexHair medullacoronalSpinous ImbricateHair root Hair follicleHair papillaHair matrixAnagen phaseCatagen phaseTelogen phasePlain weaveTwill weaveSatin weave Knitted weaveSynthetic fiber

Forensics book pages 78-79Read the case study. Based on your current knowledge, who are the best candidates for suspects?Hair: Individual or Class Evidence?Unless DNA is obtained, hair is considered to be class evidenceNuclear DNA can be obtain from hair if a follicle is attached. Hair that is forcibly pulled out is more likely to have useable nuclear DNA.Mitochondrial DNA can be found in the shaft of the hair. This DNA links families together through the female line. mtDNA will typically be class evidence since it identifies a family, but not a specific person. Enough circumstantial evidence can still give a conviction.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 cuticlecoronal (crown-like, found in small rodents and bats, rarely in humans), spinous (petal-like, found in seals, cats, & some animals never humans), and imbricate (flattened, found in humans and animals). Combinations and variations of these types are possible.

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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.

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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

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.

HAIR SAMPLES FROM DIFFERENT HUMAN RACES AND 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: flattenedHAIR SAMPLES FROM DIFFERENT HUMAN RACES AND 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

HAIR SAMPLES FROM DIFFERENT HUMAN RACES AND 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

HAIR SAMPLES FROM DIFFERENT HUMAN RACES AND 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, although more dense toward the medulla.

Human Hair vs Animal HairMedullary Index is the quickest way to determine a hairs orignin 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.

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

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

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.

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

Book workForensics book: Read pages 88-89Complete the assessment on page 90, except #1IDENTIFY AND COMPARE NATURAL AND SYNTHETIC FIBERA. Physical testing methods1. Natural fiber a. cotton flattened tubes, twisted and bentb. silk tubular, doesnt twist muchc. wool looks like animal hair, overlapping scalesd. Linen plant fiber2. Synthetic fiber Cross sections are different depending on the nozzle used when the fibers are extruded. Can included round, trilobal, dogbone or dumbbell, 4-lobed, octalobal, irregular, multi-lobed or serrate. Because of the nature of production, synthetic fibers maintain a consistent shape

Most Common FibersNatural = cottonSynthetic = polyesterIDENTIFY AND COMPARE NATURAL AND SYNTHETIC FIBERB. Chemical testing methods1. Most current fiber analysis, like paint, is done with a Fourier Transform Infrared Spectrometer (FTIR). This uses a beam of light to determine the molecular groups present in a sample. First the fiber is flattened with a small rolling pin and then transferred to the salt window. Once there, the beam of light can be focused on the fiber and a graph with peaks and valleys will appear on the computer screen. Synthetic fibers are wonderfully uniform (compared to natural fibers).

COMPARE AND CONTRAST COMMON FIBER WEAVE PATTERNSWoven fabrics are made by interlacing warp and weft yarns.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

Book WorkForensics book pgs 100 read & do the labForensics book pg 109, 110, 111, 118 do each lab, each on its own lab notebook page

5.07 ILLUSTRATE PRINICIPLE CHARACTERISTICS OF COMMON FIBERS USED IN FIBER IDENTIFICATIONhttp://www.uen.org/Lessonplan/preview.cgi?LPid=14747

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

CAREERS IN HAIR & FIBER ANAYLSIS For each career listed, find the following information:Levels of education requiredCredentialing requirementsEmployment opportunitiesWorkplace environmentsCareer growth potentialA. Forensic ChemistB. Forensics Fiber ExpertC. Computer ForensicsHair & Fiber ReviewVocabulary! Use each vocabulary word in an appropriate sentence.Draw and label a piece of hairDraw and label a follicleDescribe how to tell the difference between a human hair and an animal hairKnow the different stages of hair growth summarize eachWhat type of DNA is found in different parts of the hairKnow different examples of natural and synthetic fibers, know the most common types