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