A protein that composes hair, also found in toes and fingernails. Makes it strong and flexible
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Cortex
2nd and thickest layer, also contains the most pigment. Also the most important part for determining from which person the hair came from.
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Medulla
central core (may be absent)
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Cuticle
Clear outer coating composed of overlapping scales
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continuous medulla
one unbroken line of color
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Interrupted medulla
pigmented line broken at regular intervals
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fragmented medulla
pigmented line unevenly spaced
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solid medulla
pigmented area filling both the medulla and the cortex
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none medulla
no separate pigmentation in the medulla
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Head hair
generally circular or elliptical in cross section
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Eyebrows and Eyelashes
circular but often have tapered ends
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Beard and mustache hair
tend to be thick and triangular
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underarm hair
Can be oval or triangular
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auxiliary or body hair
Can be oval or triangular
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pubic hair
Can be oval or triangular
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Anagen Stage
long, hair actively grows - the cells around the follicle rapidly divide and deposit materials in the hair.
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Catagen stage
the hair grows and changes
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Telogen stage
the follicle becomes dormant - hairs can be lost.
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Imbricate
resembles a brick
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coronal
shapes like a cone
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spinous
looks like spines
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.5 or greater
animal hair
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.33 or less
person
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Medullary index
medullary diameter/hair diameter
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Macroscopic
investigation can indicate length, color, and curliness
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Microscopic
investigation can indicate fine detail in hair structure
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follicle
crucial for dna testing
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Fibers
used to create a possible link between crime and suspect or to recreate a crime scene/ considered class evidence
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Natural fibers
Come from plants (cotton) or animals (wool). Typically non-uniform and inconsistent in shape and structure
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Manufactured fibers
Synthetics like rayon, acetate, and polyester, which are made from long chains of molecules called polymers. Typically uniform and consistent in shape and structure
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Wool and Cashmere
Sheeps
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Mohair
goats
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Angora
rabbits
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Silk
caterpillar cocoons
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Plant fibers
absorb water and insoluble in water, very resistant to damage from harsh chemicals, dissolvable only by strong acids, becomes brittle over time.
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Cotton
most common textile plant fiber
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coir
from coconuts, is durable
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Hemp, jute, and flex
from stems, grows in bundles
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Manila and sisal
from leaves, deteriorates quickly
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Artifical fibers
man-made fibers that originate from natural materials such as cotton or wood
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Synthetic Fibers
Manufactured from chemicals, more than 50% of all fibers used in production of textile materials are synthetic or man made
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Glass fiber
extremely tiny glass fibers
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asbestos
group of six different materials made into fibers, fire resistant
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Rayon
most common in this group imitates natural fibers, but stronger
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Acetate
carpets
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polyamide nylon
lightweight clothing
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Polyester
polar fleece, wrinkle resistant, not easily broken down, added to natural fibers for strength
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Nylon
easily broken down, similar to polyester
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Acrylic
Inexpensive, balls easily, substitute for artificial wool or fur
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Olefins
quick drying, resistent to wear
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Chemical test
dissolves in strong acid (plant, silk, or manufactured) dissolves in strong base (wool)
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Burn test
order of burning hair (animal), order of burning paper (plant), melts (manufactured)
Studied by 8 people
