hair analysis forensic science chapter 8. what do you know? can the body area from which hair...

Hair AnalysisHair Analysis

Forensic ScienceChapter 8

What do you know?What do you know?• Can the body area from which hair originated by

determined?o Yes – with little difficultyo Pigment distribution, cross-section shape, diameter

• Can the racial origin of hair be determined?o Rule of thumb:

• Caucasiano Straight, wavy; even-pigment; oval-round cross section

• African-Americano Kinky; dense; uneven pigment

What do you know?What do you know?• Can the age and sex of an individual be

determined from a hair sample?o Age – NO (except infant hair – fine, short)o Sex – NO (can get ideas – bleached hair)

• Is it possible to determine if hair was forcibly removed from the body?o Yes – follicular tag will remain if forcibly removed

What do you know?What do you know?• Are efforts being made to individualize human

hair?o Nuclear DNA – both parentso Mitochondrial DNA – from mother child

• Can DNA individualize human hair?o Nuclear DNA – 1 in billionso mDNA – can exclude but not individualize!

FYIFYI• Hair is class evidence• Avg human body has 5 million hairs• Head hairs:

o Blondes have most – 120,000o Redheads – 80,000o Black/brown – 100,000

• Constantly shedding and replacing hairs – 100 per 24 hour period (scalp)

Morphology of HairMorphology of Hair• Morphology – form and structure of hair

o Clues in Crime CD – 5.2

• Made up of polymers – complex long-chained moleculeso Very resistant to breaking downo Grows from hair follicle – a tubelike organ in the dermis

• Hair root embedded in follicle• Follicle is linked to body’s blood supply – everything is distributed

into hair

Morphology of HairMorphology of Hair• Hair shaft – extends out through epidermis

o Three parts• Cuticle• Cortex• Medulla

Morphology of HairMorphology of Hair• Cuticle

o Function• Helps resist chem decomposition• Helps retain structure

o Clear outside covering of shafto Made up of tough, overlapping scales (points

towards tip of hair)• Formed by cells that have hardened (keratinized)

then flattenedo Help in species ID

• Humans – much finer pattern; not much variation• Animals – vary from species to species

o See scales?• SEM• Cast

Morphology of HairMorphology of Hair• Cuticle cont

o Three basic patterns:• Coronal• Spinous• Imbricate

Morphology of HairMorphology of Hair• Coronal

o Crown-likeo Found in hairs of very fine diameter and resembles a stack of paper

cups o Small rodents and bats but not in human hairs

Morphology of HairMorphology of Hair• Spinous

o Petal-like scales are triangular in shape and protrude from the hair shaft

o Fur hairs of seals, cats, and some other animals. They are never found in human hairs

Morphology of HairMorphology of Hair• Imbricate

o Flattened-scale type of overlapping scales with narrow marginso They are commonly found in human hairs and many animal hairs

Morphology of HairMorphology of Hair• Coronal, Spinous, or Imbricate??

Morphology of HairMorphology of Hair Cortex

Made up of keratin (tough protein polymer made up of about 20 different amino acids)

Contains color pigment – Melanin Eumelanin - responsible for black and brown color Phaeomelanin - responsible for red shades Blondes – low amounts of melanin – shade of blonde depends on

what type of melanin you have Absence of pigment = gray or white hair

Cortical fusi – little sacs of air Come in different size and shapes Can see under a magnification of 100x

Morphology of HairMorphology of Hair Medulla

Cellular column through center of hair – like a canal or spinal cord; no known function

Predominant feature of hair More than ½ of diameter of hair Medullary index – calculated to help ID species

Medullary index = diameter of medulla diameter of hair shaft

Expressed as a fraction Humans < 1 3 Others > 1

2

Morphology of HairMorphology of Hair• Medulla – cont

o Varies extensively• NOT all hairs have one• Types:

o Continuouso Interrupted/Intermittent – even breakso Fragmented (segmented) – uneven breakso Absent

Humans normally – absent or fragmented

Morphology of HairMorphology of Hair• Medulla Conto Patterns

• Uniserial - Cat• Multiserial - Rabbit• Lattice - Deer• Vacuolated - Dog• Amorphous - Human

Morphology of HairMorphology of Hair• Shape of hair

o Straight, curly, kinkyo Depends on cross-section of the hair shaft

• Round – straight hair• Less Round– curly hair• Oval/Elliptical– kinky hair

o Generalizations:• Asians/Native Americans – round, no twisting• American/European whites, Mexicans, Middle East – less round,

rare twist (undulation), evenly distributed pigment• African – oval or elliptiacl, twist, clumped pigmentation

Morphology of HairMorphology of Hair• Hair Root

o Grows at about 1cm/montho Three stages of growth

• Anagen Phase• Catagen Phase• Telogen Phase

Anagen PhaseAnagen Phase• Lasts up to five years• Includes 80-90% of hair follicles at any one time• Initial growth• Hair bulb attached to blood supply• http://www.hairlosshelp.com/hair_loss_research/

hair.cfm

Catagen PhaseCatagen Phase• Intermediate Phase• Lasts 2-3 weeks• Hair bulb Detached from blood supply• http://www.hairlosshelp.com/hair_loss_research/

hair.cfm

Telogen PhaseTelogen Phase• Lasts 2-6 months• 8-10% of all hair follicles• Sheds hair naturally• Follicular Tag – tissue pulled with hair; contains

DNA• http://www.hairlosshelp.com/hair_loss_research/

hair.cfm

Summary of Hair Summary of Hair GrowthGrowth

Morphology of HairMorphology of Hair• Hair Tip

o External Endo Mature Hair

• Will taper to a pointo Cut Hair

• Will be squared off (but within 2-3 weeks will become rounded)o Frayed or split ends

• Dryness or lack of care

Identification and Identification and Comparison of HairComparison of Hair

• Identifyo Race

• Generally – yes, by cross-sectional shapeo Age

• No – except infantso Sex

• No – can generalizeo Forcibly Removed?

• Yes – more tissue = more force

Identification and Identification and Comparison of HairComparison of Hair

• Compareo Scale structureo Medullary indexo Medullary shapeo Coloro Lengtho Diametero Pigment intensityo Infections/abnormalities

Hair as a Chemical Hair as a Chemical IndicatorIndicator

• Many drugs and their metabolites (specific product of drug interaction with body) can be detected in just a few mm of hair

• Because of hair slow growth – longer periods of drug use can be detected

• Metal contento Diagnose dietary deficiencies and diseaseo Poisoning

• Hg, Pb, As

Hair as a Chemical Hair as a Chemical IndicatorIndicator

• Person’s environmento Scalp oils can find traces of environmento Detect smoke from crack cocaine, industrial pollution

Collection and Collection and Preservation of HairPreservation of Hair

• Always accompanied by reference samples• Normally need

o 50 scalp hairs• Full length• Pull out or clip at skin line

o 24 pubic hairs

Case StudyCase Study• Ennis Cosby – 1997

o 27 years oldo Got a flat tire – pulled off the road to put spare – Bel-Airo Shortly after – an assailant demanded money and when Ennis didn’t

respond quickly enough, was shot in the templeo A .38 revolver was later found miles from the scene

Case StudyCase Study• Mikail Markhasev (Ukranian immigrant –

age 19) was arrested and charged with murder

• Hair was recovered from Ennis’s hato Identified 6 DNA markers from tissue that

matched Markhasev’s DNA

• Markhasev was convicted of murdero serving life sentence without

possibility of parole

Case StudyCase Study• Napoleon

o Died in exile in 1821o By analyzing his hair, some believe he was poisoned by the deliberate

administration of arsenic; others suggest it was vapors from the dyes in the wallpaper that did him in.

Case StudyCase Study• John Vollman

o Clues in Crime CD

Wrongful AccusationWrongful Accusation