Download presentation
1
Hair Analysis
2
Functions of Hair Regulates body temperature
Arrector pili muscles contract to create “goosebumps” Protection against sunlight In nonhuman mammals, hair is known as fur Can be used as physical evidence Identify individuals Narrow down group of suspects Trace evidence that overrides other evidence Can place an individual at a crime scene
3
Anatomy of Hair Composed of dead keratinized cells, melanin, lipids, and water mtDNA can be extracted from these cells Only transferred from mother Produces sebum in order to Protect Lubricate Waterproof Inhibit microorganisms
4
History in hair Nicolaus Copernicus was buried in a Cathedral in Poland beneath the altar floor, and his remains were unmarked In 2005, his skull and remains were unearthed by archaeologists and extracted mtDNA from teeth and femur bone There were two hairs found in Copernicus’ library back in Sweden and the mtDNA matched the remains in Poland In 2010, his remains were reburied where originally found
5
Anatomy of Hair Composed of three layers Cuticle is the outer region
Cortex is the area between the cuticle and medulla where pigment granules of melanin are located Medulla is the middle region
6
Cuticle Translucent outer region of hair
Scales point toward the tip of the hair Can feel directionality by running fingers to end and then run back to scalp 6-10 cells thick Protects hair with waterproofing Susceptible to damage Pattern determines species
7
Cuticle
8
Cortex Pigment molecules Bulk of the hair shaft
Differs in the color, shape, and distribution of granules
9
Medulla Center part of the hair shaft
Can be interrupted, missing, or continuous Medullary index Ratio of hair shaft to medulla >0.5 = animals >0.3 = humans
10
Medulla
11
Hair Analysis – Origin of Species
Animal Human Pigmentation Denser toward the middle Denser toward the cuticle Banded color patterns Possible None Medulla Thicker Thinner
12
Hair Analysis – Origin of Location
Shape and length indicates body location Location Description Head hair Circular or elliptical Little diameter variation More uniform color distribution Eyebrows/Eye lashes Circular – often tapered Beard hair Thick and triangular Course with double medulla Blunt ends Body hair Oval or triangular Arms/legs – blunt tip/frayed ends Pubic hair Buckling may be present Large variation in diameter Continuous medulla
13
Hair Analysis – origin of Location
Pubic (buckling) Arm/Leg (frayed end) Beard (double medulla)
14
Stages of Hair Development
Length of cycle if genetically programmed Humans – each follicle has its own timeline Animals – timed to occur simultaneously at times of shedding Anagen Hair actively grows May last up to six years Root is attached to the follicle (bulb shape) Catagen Hair grows and changes 2-3 weeks Roots elongate in appearance Telogen Follicle becomes dormant Hair is pushed out of the follicle (shedding) 2-6 months 4-5 year cycle on human head 3-4 months for eyebrows
15
Hair Analysis – Origin of Race
Appearance Pigment Granules Cross-Section Other Info European Generally straight or wavy Small and evenly distributed Oval or round of moderate diameter with minimal variation Colors include red, blond, brown or black Asian Straight Densely distributed Round with large diameter Thick cuticle Continuous medulla African Kinky, curly, or coiled Densely distributed, clumped, may differ in size and shape Flattened with moderate to small diameter and considerable variation
16
Hair Analysis – Origin of Race
European Asian African Appearance Cross-Section
17
Challenge! Cat Horse Pig Human Deer Dog Rabbit Rat Human
Use the photos below to identify the organism that the hair comes from Choices: Cat Deer Dog Horse Human Pig Rabbit Rat *One of the above is used twice! Cat Horse Pig Human Deer Dog Rabbit Rat Human
18
Other Info… Hair grows out of the skin
Chemicals that skin absorbs can be incorporated into hair Arsenic Lead Cocaine Morphine Tobacco Heroin Amphetamines Environmental exposure (dirt, smoke) Long term use of alcohol
19
Analysis of Hair Analyzing hair at different locations along the shaft gives a timeline of exposure Neutron activation analysis Can detect different elements in a 2 cm long piece of hair by concentration Probability if 2 individuals having the same concentration of different elements is one in one million
20
HAIR fORENSICS Hair identification process involves the examination and comparison of hair characteristics along the entire length of the hair Longer hairs have more characteristics to compare and greater variation along the length Hair evidence is usually only used in conjunction with other evidence
21
Hair Forensics
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.