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Chapter 5 & 6:Chapter 5 & 6:
Hair and FiberHair and Fiber
“For three days after death, hair and fingernails continue to grow but
phone calls taper off.”
—Johnny CarsonComedian and television host
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Hair - a thin filament produced by mammals from a hair follicle
Made of protein called keratin (makes fingernails too)
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Hair is class – biological - circumstantial evidence
unlessDNA is recovered making
it _________________________
evidence
Individual – biological - circumstantial
HAIR IS HAIR IS MORPHOLOGICALLY MORPHOLOGICALLY
LIKE A PENCILLIKE A PENCIL
Medulla
Cortex
Cuticle
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The MedullaThe Medulla
medulla = hair core (not always visible)
.
.
The MedullaThe Medulla
medulla = hair core (not always visible)
.
.
.
The MedullaThe Medulla
.
.
Same hair under Same hair under microscopemicroscope
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Every hair (animal/human) has a cuticle and cortex.
The medulla is the “WILD CARD”. It can be:absent / presentcontinuous / fragmentedthick / thinsquare / circles
Human medulla Human medulla identifiedidentified
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Medullary IndexMedullary Index
human hair width has generally less than 1/3 medulla.
animal hair width is generally greater than 1/3 medulla.
mouse
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Hair ShaftHair Shaft Cuticle—
outside scales
cOrtex— pigment (a color speck) ovoid body (big color speck) contains air pockets (why
hair floats)
Medulla— although it’s black, it doesn’t
contribute to hair color NO PIGMENT
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The CuticleThe Cuticle
The cuticle (scales) differ between species of animals and are named based on their appearance.
The three basic patterns are:
Coronal Spinous Imbricate
cuticlecuticle
healthy16
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Scale cast of Scale cast of Human HairHuman Hair
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Hair Growth (3 parts)Hair Growth (3 parts)
Anagen—hair that is actively growing
Catagen—hair is resting
Telogen—hair that is dying and ready to fall out
Anagen Anagen catagen catagen telegentelegen
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CLEAR CELLS ATTATCHED TO ROOT INDICATE THE HAIR WAS
FORCIBLY REMOVED
CROSS SECTION OF HAIRCROSS SECTION OF HAIR
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Hair as class evidenceHair as class evidence
Color Length Distribution, shape and
color intensity of pigment granules Dyed hair has color in
cuticle and cortex Bleaching removes pigment
and gives a yellow tint
Scale types Presence or
absence of medulla
Medullary type Medullary pattern Medullary index
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DNA from HairDNA from Hair
Only the root contains DNA.
hair ripped out has more root attached
The hair shaft contains abundant mitochondrial DNA (inherited ONLY from mom).
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Collection of HairCollection of Hair Hair is best retrieved at crime scene by
gloved hand (not tweezers) Questioned hairs must be accompanied by
an adequate number of control samples. from victim from possible suspects from others who may have deposited hair at the
scene
Control Sample 50 full-length hairs from all areas of scalp 24 full-length pubic hairs
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Hair ToxicologyHair Toxicology
Advantages: Easy to collect and store Is externally available Can provide information on the individual’s
history of drug use or of poisoning.
Collections must be taken from different locations on the body to get an accurate timeline.
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Hair ToxicologyHair Toxicology
Napoleon died in exile in 1821. By analyzing his hair, some investigators suggest he was poisoned by the deliberate administration of arsenic; others suggest that it was vapors from the dyes in the wallpaper that did him in.
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More about HairMore about Hair
For additional information about hair and other trace evidence, check out Court TV’s Crime Library at:
www.crimelibrary.com/criminal_mind/forensics/trace/1.html
A lab on hair analysisA lab on hair analysis
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In order to visualize the
scales: paint clear fingernail polish on a glass slide when the polish begins to dry, place a hair on the polish when almost dry, lift off the hair and observe the scale
imprints
What pattern is seen in
this slide?
Demodicidae Demodicidae
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The CortexThe Cortex
The cortex gives the hair its shape.
It has two major characteristics: Melanin—pigment granules that give hair its
color
Cortical fusi—air spaces, usually found
near the root but may be found throughout
the hair shaft
Different hair Different hair
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Split End of Human Split End of Human HairHair
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Students will be able to: Describe the structure of
a hair Explain the difference
between human and animal hair
Explain which characteristics of hair are important for forensic analysis
Assess the probative value of hair samples
Hair AnalysisHair Analysis
Hair AnalysisHair Analysis hair is biological class
evidence hair can be used to back
up circumstantial evidence
hair easily holds substances absorbs (from within
body) adsorbs (rests on
outside) substances
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IntroductionIntroduction
hair most frequently found pieces of evidence at the scene of a violent crime.
can provide a link between the criminal and the crime.
From hair one can determine: If the source is human or animal Race (sometimes) Origin of the location on the source’s body Whether the hair was forcibly removed If the hair has been treated with chemicals If drugs have been ingested
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Hair from skinHair from skin
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Hair ShapeHair Shape
Can be straight, curly or kinky depending on the cross-section, which may be round, oval or crescent-shaped
Round(Straight)
Oval(Curly)
Crescent moon (Kinky)
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The RootThe RootHuman roots look different based on whether they have been forcibly removed or if they are telogen hairs and have fallen out. Animal roots will vary, but in general have a spear shape.
Fallen out Forcibly removed