Ch. 3

Hair

Napoleon Hair (watch beginning)

Neutron activation analysis (old)- 18 min

Napoleon Poisoning Claims Debunked

Forensic Analysis of Hair

Trace evidence- hair and fiber

Hair EvidenceClass evidence

1st job: determine if animal or human

Composed of protein (keratin), an appendage of the skin that grows out of hair follicle

Each species possesses hair w/ characteristics length, color, shape, root appearance & internal features

Types of hair recovered & condition & number of hairs collected all impact their value as evidence

Morphology

Study of the structure or form of hair

Function of Hair

Regulate body temp

Decrease friction

Protect against sunlight

Sense organ

Camoflauge

The Structure of Hair

The Structure of Hair

The Structure of Hair

Phases (development stages)Anagen

Cyclical growth

Initial growth period where follicle is actively producing hair (materials are deposited in cells)

May last 3-6 years, 80-90 % of hair is this phase

Follicular tag- root is attached to follicle for growth, when hair is yanked out root is still attached- can use tag for DNA

Catagen

Transition period

Occurs between anagen & telogen phases

2% in this phase

Roots are elongated

Telogen

Resting phase

10-18% of hair

Most commonly found piece of evidence

Last about 100 days, easily dislodged

Root is club shaped

Final growth phase in which hair sheds

Parts of Hair

Hair is an appendage of the skin that grows out of an organ known as the hair follicle

Hair follicle: origin of growth of the root, shaft and tip club shaped structure in skin w/ network of

blood vessels called papilla that supply nutrients

Shaft: composed of protein keratin, consists of 3 layers

Cuticle

Allows hair to be resistant to chemicals & allows hair to retain structural features over a long timeFormed by overlapping scale (hardened cells)Scales on animals look like roof shinglesScales can be: coronal, spinous, or imbricateStudy by making casts (embedded in nail polish)

Cortex

Main body of hair

Contained w/ in the protective cuticle

Made of spindle-shaped cortical cells aligned in the shaft

Pigment granules found in cortex (major use in evidence- get diff. shapes, color, distribution)

Can look at cortex if you prepare slide w/ liquid that has same index of refrac. as hair

Medulla

Collection of cells having the appearance of a central canal running through hair

Varies among individuals

Classified as continuous, interrupted, fragment, absent

Medullary index (M.I.) = diameter of medulladiameter of shaft

Casey anthony -hair

Other types of human hair

-used to corroborate other evidence

-make connections

Pubic

Need 25 hairs, routinely compared (head hair- normally 50)

Not subject to change (sample can be taken 1 year after crime- can still be compared)

Course and wiry, buckling can be present

Facial

Not meaningful, establish contact

Coarse, triangular cross section

Wide medulla, razor cut tip

Limb Hairs

Not meaningful

Short, arc like

Medulla – trace to discontinuous

Fringe hairs

Neck, side burns, abdomen, upper leg, back

Other body hair

Underarm, chest, eye, nose

Not routinely compared

Animal Hair

Used to link a suspect or location

Get transfer (from animal or secondary source)

Animals don’t possess enough indvl. microscopic characteristics to be associated w/ 1 particular animal

Can determine type of animal or breed

Animal hairs vary- in color & length from different parts of the body

Collect full length hairs

Some hairs found may be cut fur coat, rug, etc

Animals vs. Humans

Animal

MI ½ or greater

Medulla= continuous or interupted

Shape = patterned Cat=pearl Deer = spheres

Human

MI 1/3 or less

Medulla= fragmented or absent

Shape = cylindrical

Age and Sex

Age Can’t be determined definitively by microscope But hairs in infants finer, less distinctive Older hair finer, more variable in diameter

Sex Can do DNA w/ follicular tag (rare) Can also stain the sex chromatin in cells (Barr

body or y-body) Treated (perm,color) more frequent in females

Barr Body Y-Body

Racial Determination

Caucasoid (European) Fine to medium coarseness Straight or wavy Blonde to brown/black in color Shafts – round to oval in cross section Have medium sized, evenly distributed pigment

granules Color- blonde, red, brown or black

Mongoloid (Asian) Coarse, straight, circular cross section Wider diameter Cuticle thicker Medulla continuous & wide Pigment granules are larger than caucasoid,

densely distributed Can have reddish appearance

Negroid (African) Curly, kinky Flattened cross section Pigment granules are larger than other groups-

in clumps Can be buckled (twisted shaft) & shaft is

frequently split

Identification and comparison of hair

Hair is class evidence

Identification involves: Scale structure, medullary index, medullary

shape

Compare: Color, length, diameter, medullary charac.,

cortical cells, artificial pigmentation (dyed or pigmentation – 1cm/month growth)

Forensic exam: Addresses body area, racial origin, mechanism

of removal, possibly age or sex

Analysis Techniques

Microscopy: Compound Comparison (most common) Fluorescence Electron

Neutron Activation Analysis- method of analysis that determines the composition of elements

Buckled hair Burnt hair Cut tip

Razor cut

Split endPost mortem root band

Human hair Orangutan

Bat hair- coronal pattern

Mink hair- spinious

Rabbit- ladder medulla

Dyed hair

Hair w/ lice egg

Limb hairPubic hair

Beard hair

FBI Hair Website

fbi video (old)