forensic lab investigations. hair analysis what is hair? what is hair? produced by hair follicle...

Forensic Lab Forensic Lab InvestigationsInvestigations

Hair AnalysisHair Analysis

What Is Hair?What Is Hair? Produced by hair follicleProduced by hair follicle Consists of:Consists of:

Shaft (projects from skin) and a root Shaft (projects from skin) and a root (embedded in the follicle)(embedded in the follicle)

Shaft is flat and ribbon-like in cross-section – curly Shaft is flat and ribbon-like in cross-section – curly hairhair

Oval shaft – wavy hairOval shaft – wavy hair Round shaft – straight hairRound shaft – straight hair

Hair AnalysisHair Analysis

Three layers of protein:Three layers of protein: MedullaMedulla – center section made of large – center section made of large

cells separated by air spacescells separated by air spaces CortexCortex – surrounds medulla; bulky with – surrounds medulla; bulky with

several layers of flattened cellsseveral layers of flattened cells CuticleCuticle – outermost layer, looks like – outermost layer, looks like

shingled roofshingled roof Greatest source of strengthGreatest source of strength Contains pigments – small, dark, and solid Contains pigments – small, dark, and solid

structures that are granular in appearancestructures that are granular in appearance

Hair AnalysisHair Analysis

Hair Types:Hair Types: Scalp – uniformScalp – uniform Beard – coarse, curvedBeard – coarse, curved Eyebrow, nose, ear, eyelid – shorter and Eyebrow, nose, ear, eyelid – shorter and

stubbier, wide medullas; taper at endstubbier, wide medullas; taper at end Axillary – uneven pigments; fine point at endAxillary – uneven pigments; fine point at end

How did it come out?How did it come out? Fell out – bulblike rootFell out – bulblike root Pulled out – sheath attached to bulb or Pulled out – sheath attached to bulb or

mutilated appearancemutilated appearance

Scale Pattern: Human Hair

Hair AnalysisHair Analysis Hair Identification: Animal Versus Human Hair Identification: Animal Versus Human

HairsHairs PigmentationPigmentation

Human Hairs are consistent in color and pigmentationHuman Hairs are consistent in color and pigmentation Pigmentation is evenly distributed, or slightly more dense Pigmentation is evenly distributed, or slightly more dense

toward the cuticletoward the cuticle Animal hairs exhibit radical color changesAnimal hairs exhibit radical color changes

Pigmentation is more centrally distributed, more dense toward Pigmentation is more centrally distributed, more dense toward the medulla the medulla

MedullaMedulla In human hairs, has a width that is generally less than In human hairs, has a width that is generally less than

one-third the overall diameter of the hair shaftone-third the overall diameter of the hair shaft In animal hairs, generally occupies an area of greater In animal hairs, generally occupies an area of greater

than one-third the overall diameter of the hair shaftthan one-third the overall diameter of the hair shaft RootRoot

Human hairs roots commonly club-shapedHuman hairs roots commonly club-shaped Animal hairs roots highly variableAnimal hairs roots highly variable

Pigment in Animal Hair

Human Hair: Root

Hair AnalysisHair Analysis

Microscopic ExaminationMicroscopic Examination Why Examine?Why Examine?

Decays slowly compared to tissues and Decays slowly compared to tissues and fluidsfluids

May have to compare hundreds of May have to compare hundreds of samplessamples

Indicate physical contactIndicate physical contact

Hair AnalysisHair Analysis

What information can a forensic scientist What information can a forensic scientist obtain from a hair sample?obtain from a hair sample? The source (human or animal)The source (human or animal) The ageThe age Hair pulled out or fell outHair pulled out or fell out Treatment of hairTreatment of hair Indicates if bleached or dyedIndicates if bleached or dyed

Dyed have less prominent pigment granulesDyed have less prominent pigment granules Hair grows about ½ inch per monthHair grows about ½ inch per month

What part of bodyWhat part of body Drugs, soil, liceDrugs, soil, lice DNA analysisDNA analysis

Human Hair: Brown vs. Red

Human Hair Types

Limb Hair versus Facial Hair

Differences in Hair

Hair Cut Types:

Rounded Cut

Broken Worn Razor

Abraded

Dyed Hair