Hair AnalysisHair Analysis
Encountered in a wide variety of Encountered in a wide variety of crimescrimes Especially useful in rape casesEspecially useful in rape cases Also useful in illegal drug usage cases Also useful in illegal drug usage cases
(toxicology)(toxicology) Many attempts have been made to Many attempts have been made to
positively identify a suspect but all positively identify a suspect but all have failedhave failed Hair is usually class characteristic onlyHair is usually class characteristic only
Typically need more than oneTypically need more than one
Vital PropertiesVital Properties
Species identificationSpecies identification Color/PigmentColor/Pigment LengthLength DiameterDiameter Internal characteristicsInternal characteristics Dye/BleachingDye/Bleaching
Hair as EvidenceHair as Evidence
Hair evidence is evaluated by Hair evidence is evaluated by physical microscopy or chemical physical microscopy or chemical analysisanalysis
ToxicologyToxicology Hair acts like a time capsuleHair acts like a time capsule Base of hair shows most recent useBase of hair shows most recent use Protein structure “freezes” evidence of Protein structure “freezes” evidence of
drugs, heavy metals, etc. in hairdrugs, heavy metals, etc. in hair Typical human head hair growth is 1 cm Typical human head hair growth is 1 cm
per monthper month Rape/HomicideRape/Homicide
Source of DNA in follicular tissueSource of DNA in follicular tissue
Hair as EvidenceHair as Evidence
Species identificationSpecies identification Most species of mammals are Most species of mammals are
distinctly different from each other distinctly different from each other under a microscopeunder a microscope
Human ethnicityHuman ethnicity Can usually identify ethnicity in Can usually identify ethnicity in
humanshumans
Human EthnicityHuman Ethnicity CaucasoidCaucasoid
Usually straight or wavyUsually straight or wavy Evenly distributed, usually fine pigmentationEvenly distributed, usually fine pigmentation Oval to round cross sectionOval to round cross section Fragmented/absent medullaFragmented/absent medulla
MongoloidMongoloid Usually straightUsually straight Usually even, dense pigmentationUsually even, dense pigmentation Continuous medulla (defining characteristic)Continuous medulla (defining characteristic)
NegroidNegroid KinkyKinky Dense, unevenly distributed pigmentDense, unevenly distributed pigment Flat to oval cross sectionFlat to oval cross section Fragmented/absent medullaFragmented/absent medulla ““Buckling” often seenBuckling” often seen
Typical human hair cross sections
Hair Evidence MythsHair Evidence Myths
AgeAge Age can not be determined with any amount Age can not be determined with any amount
of certaintyof certainty Only infants seem to have distinct Only infants seem to have distinct
characteristicscharacteristics Usually very fineUsually very fine
GenderGender Gender can not be determined without Gender can not be determined without
follicle and DNA analysisfollicle and DNA analysis Male/Female structure identicalMale/Female structure identical Differences mainly genetic in natureDifferences mainly genetic in nature
Hair Evidence MythsHair Evidence Myths
DNA extractionDNA extraction Can be extracted from follicular tissue Can be extracted from follicular tissue
or root (in some cases)or root (in some cases) Cut hair without the root usually does Cut hair without the root usually does
not contain enough DNA to typenot contain enough DNA to type If forcefully removed, follicle tissue w/ If forcefully removed, follicle tissue w/
DNA likely attached to rootDNA likely attached to root Hair that falls out naturally does not Hair that falls out naturally does not
contain adhering tissuecontain adhering tissue
Body Hair TypesBody Hair Types
Forensically valuable hairForensically valuable hair Scalp hairScalp hair
Little diameter differencesLittle diameter differencesUniform pigmentUniform pigmentExposure to environmental conditions Exposure to environmental conditions
make immediate processing vitalmake immediate processing vital Pubic hairPubic hair
Vary widely in diameterVary widely in diameterUsually curlyUsually curlyShort lengthShort lengthLess exposure to elements allows for Less exposure to elements allows for
collection long after crimecollection long after crime
Body Hair TypesBody Hair Types Lesser forensic valueLesser forensic value
Most other body hairs are too variable in Most other body hairs are too variable in appearance to be valuable for forensicsappearance to be valuable for forensics
Characteristics are in no way linked to patterns Characteristics are in no way linked to patterns found on scalp hairfound on scalp hair
Can be used to determine a suspect’s presence Can be used to determine a suspect’s presence at scene but not often usedat scene but not often used
Three typesThree typesLimb - arm, legLimb - arm, legFringe hair - neck, sideburns, upper leg, backFringe hair - neck, sideburns, upper leg, backAxillary - eyebrows, nose, underarmAxillary - eyebrows, nose, underarm
Hair StructureHair Structure
Structural componentsStructural components EpidermisEpidermis
Outermost layer of skinOutermost layer of skin Pitted with hair folliclesPitted with hair follicles
RootRoot Portion of hair below skinPortion of hair below skin
FollicleFollicle Only segment of hair that Only segment of hair that
is livingis living Source cells from which Source cells from which
hair growshair grows Below skin in the bulbBelow skin in the bulb
Hair StructureHair Structure
Structural componentsStructural components Arrector (Erector) MuscleArrector (Erector) Muscle
Can cause hair to stand Can cause hair to stand on endon end
Also source of Also source of “goosebumps”“goosebumps”
Many animals have Many animals have control over these control over these musclesmuscles
Hair StructureHair Structure
Structural componentsStructural components Hair shaftHair shaft
Composed of protein Composed of protein keratinkeratinStructurally the same Structurally the same
as fingernailsas fingernailsThree layersThree layers
Cuticle, Cortex, Cuticle, Cortex, MedullaMedulla
Hair StructureHair Structure Structural componentsStructural components
CuticleCuticleProvides support for hairProvides support for hairNon-livingNon-livingConsists of overlapping Consists of overlapping
external scales different external scales different than most other than most other mammalsmammals
Scales very resistant to Scales very resistant to decompositiondecompositionMakes for perfect Makes for perfect
physical evidencephysical evidence
Hair StructureHair Structure Structural componentsStructural components
CortexCortex Inner layer of hairInner layer of hairContain pigment Contain pigment
granulesgranulesMelanin proteinMelanin protein
Distribution of pigment Distribution of pigment helps to determine helps to determine particular individualsparticular individuals
Hair StructureHair Structure Structural componentsStructural components
MedullaMedullaA “tube” of cells that run A “tube” of cells that run
up the center of the up the center of the cortexcortex
Width of medulla is Width of medulla is vitally important in vitally important in identifying speciesidentifying species
Ratio of hair width to Ratio of hair width to medulla width is called medulla width is called medullary indexmedullary index
Hair StructureHair Structure Structural componentsStructural components
MedullaMedulla Humans have less than 1/3 Humans have less than 1/3
medulla, most other medulla, most other animals at least ½animals at least ½
Comparison of human hair
(left), deer hair (top) and dog hair (right)
Hair StructureHair Structure Structural componentsStructural components
MedullaMedullaNot always present in Not always present in
certain ethnicitiescertain ethnicitiesOne person can have One person can have
multiple medulla multiple medulla structuresstructures
ContinuousContinuous InterruptedInterruptedFragmentedFragmented
Human Medulla TypesHuman Medulla Types
Typical human medulla types. From left to right: Continuous, Interrupted, Fragmented.
Hair StructureHair Structure
Artist’s conception and electron microscope images of a human hair with cuticle, cortex and (to a lesser extent) medulla
Hair GrowthHair Growth Growth cycle has three distinct phasesGrowth cycle has three distinct phases
Hair can stay on head for approx. 6 yearsHair can stay on head for approx. 6 years If forcefully pulled out and in one of first two If forcefully pulled out and in one of first two
phases, follicle tissue will likely be found phases, follicle tissue will likely be found with the hair folliclewith the hair follicle
(right) Diagram showing the
three phases of hair growth
Hair GrowthHair Growth AnagenAnagen
Up to six yearsUp to six years Root attached to follicleRoot attached to follicle Root will have a Root will have a
“flame” shape“flame” shape If pulled out, will usu. If pulled out, will usu.
have follicular tissue have follicular tissue and show evidence of and show evidence of stretching/forcestretching/force
Growth originates at Growth originates at base of hair and base of hair and grows upgrows up
80-90% of all hair will 80-90% of all hair will be in this phasebe in this phase
(Above)Electron microscope image showing new anagen follicles erupting from the epidermis. (Below) A typical
anagen follicle with attached tissue.
Hair GrowthHair Growth
CatagenCatagen Two to three weeksTwo to three weeks Growth slowerGrowth slower Root shrinks and is pushed out of Root shrinks and is pushed out of
folliclefollicle Usu. has a shrunken appearanceUsu. has a shrunken appearance 2% of all hair2% of all hair Transition phaseTransition phase
Hair GrowthHair Growth
TelogenTelogen Two to six monthsTwo to six months No growthNo growth Root has a club Root has a club
shape with no tissueshape with no tissue Is shed naturallyIs shed naturally 10-18% of all hair10-18% of all hair
A typical telogen hair follicle. Note the absence of
follicular tissue.
Hair MicroscopyHair Microscopy
Damaged cuticle showing loose scales.
Typical wear and tear with dislodged scales and
other debris on hair follicle.
Hair MicroscopyHair Microscopy
Severely damaged hair that may be the result of
braiding or forceful removal.
A “split end” on a hair follicle. Also note evidence of cutting
by sharp scissors. Electric clippers usually leave much
more ragged marks.
Hair MicroscopyHair Microscopy
A twisted/stretched root…clear indicator of forceful removal.
Tight, twisted appearance and scorch marks of hair exposed
to high heat.
The Atlanta Child MurdersThe Atlanta Child Murders 1979-1981, 29 black males were murdered 1979-1981, 29 black males were murdered
(ages 7-16 except for last 7 who were 17-27)(ages 7-16 except for last 7 who were 17-27) Strangled, beaten, asphyxiatedStrangled, beaten, asphyxiated
Only common evidence were fibers and Only common evidence were fibers and presence of dog hairpresence of dog hair
Two artificial fibers ID’edTwo artificial fibers ID’ed After info. leaked to press, M.O. changed and bodies After info. leaked to press, M.O. changed and bodies
were dumped in riverwere dumped in river PD staked out Chatahoochee RiverPD staked out Chatahoochee River
PD heard a loud splash and stopped a suspect (Wayne PD heard a loud splash and stopped a suspect (Wayne Williams)Williams)
Claimed it was garbageClaimed it was garbage Suspect released but body later found nearby Suspect released but body later found nearby
w/ single carpet fiber in hairw/ single carpet fiber in hair
The Atlanta Child MurdersThe Atlanta Child Murders
Warrant obtained for Williams’ house and Warrant obtained for Williams’ house and found matching carpet and dog hair/fibersfound matching carpet and dog hair/fibers Expert assistance obtained from DuPont Expert assistance obtained from DuPont
corporationcorporation Exhaustive use of statistical likelihood of Exhaustive use of statistical likelihood of
particular carpet being found in a single particular carpet being found in a single Atlanta home 1:7792Atlanta home 1:7792
Additional fiber matches w/ victims’ found Additional fiber matches w/ victims’ found from Williams’ carfrom Williams’ car Chevrolet assisted in this part of investigationChevrolet assisted in this part of investigation Statistical possibility 1:3828Statistical possibility 1:3828
The Atlanta Child MurdersThe Atlanta Child Murders
Combined, 1:30 million Combined, 1:30 million chance of both matches chance of both matches being achievedbeing achieved In total, 29 fiber type In total, 29 fiber type
matches found between matches found between Williams’ possessions and Williams’ possessions and victimsvictims
Found guilty after 12 Found guilty after 12 hours of deliberationhours of deliberation Serving 2 life sentencesServing 2 life sentences Still maintains innocence Still maintains innocence
and has attempted and has attempted retrialsretrials
Wayne Williams at his arraignment in February 1982.