Aim: How is hair analyzed in
forensics?
Do Now: Explain the possible drawbacks of
analysis of hair for drug metabolites.
Homework:Pg. 230 #’s q 1-10
Substance
Urine
Hair
Blood/Saliva
Alcohol
6–24 hours
up to 2 days
12–24 hours
Methamphetamine
3 to 5 days
up to 90 days 1–3 days
MDMA (Ecstasy
24 hours
up to 90 days 25 hours
Cannabis
3 to 7 days, up
to >30 days
after heavy use
and/or in users
with high body
fat
up to 90 days 2–3 days in blood,
up to 2 weeks in
blood of heavy
users. Saliva for
Cocaine
2 to 5 days
up to 90 days 2 to 5 days
Cotinine (a break-down
product of nicotine)
2 to 4 days
up to 90 days 2 to 4 days
Heroin
3 to 4 days
up to 90 days 1– 2 days
LSD
24 to 72 hours
up to 90 days 0 to 3 hours
2–6 hours
What other materials can be traced in hair?
• Poisoning by heavy metals (Arsenic, Mercury,
lead)
• Dietary deficiencies (low vitamin and mineral
levels)
What is a drawback to hair testing?
• Scalp oils coat the cuticle of the hair and sometimes
capture materials from environment Ex: crack smoke
in car
• Can cause “false positives”
• Scientists must be careful to examine only the cortex
of the hair
Types of Animal Hairs - Key
Cat
A
Rabbit
B
Dog
D
Rat
C
Human
E
Parts of a hair strand
• 3. Tip/ End of Hair
– Often seen burned cut, razored, or with split ends
How do we get different hair colors?
1. The type of natural color pigment melanin present in your
hair's cortex.
– Eumelanin (black pigment)
– Phenomelanin (red/yellow pigment)
2. How many melanin granules exist
3. Whether those granules are close together or far apart
How do we get straight, wavy, curly,
and kinky scalp hair?
-It is due to differences in the cross section of the hair
Typically found
in people of
Native American
and Asian
descent
Typically found in
people of European
descent
Typically found in
people of African
American
descent
Wednesday 4/18/12
• AIM: how can we determine the ethnicity
of a hair sample?
• DO NOW: Explain how you would
determine the species of a hair sample?
• HOMEWORK: textbook page 230-231.
questions 11-15.
• I AM COLLECTING MONDAY TUESDAY
AND WEDNESDAY’s Homework
TOMORROW
How does scalp hair vary by race?
• Asian/Native American
– Round hair shaft - straight
– Large pigment granules
– Patchy distribution of
pigment
– Usually continuous medulla
• European/Caucasian
– Slightly round to oval hair
shaft
(straight to curly)
– Finer pigment granules
– More even distribution of
pigment
– Usually absent or
fragmented medulla
How does scalp hair vary by race?
• African American
– Flat to oval hair shaft
(curly to kinky)
- Largest and most dense
pigment granules that are
unevenly distributed
-Absent or fragmented medulla
HEAD HAIR:
Caucasian (left)
Asian/Native American
( bottom left)
African American (bottom
right)
Thursday 4/19/12
• AIM: How can we determine the origin of a
hair sample?
• DO NOW: 1- Take out the homework from
Monday, Tuesday and Wednesday
• 2- 2 minute mystery: speeding train
• Homework: THERE IS NONE!
• How can you determine the part of the
body a hair comes from?
Can The Body Area From Which A
Hair Originated Be Determined?
SCALP HAIR:
small variation in diameter
uniform distribution of pigment color
PUBIC HAIR
short and curly
wide variation in diameter.
BEARD HAIR
coarse, triangular in cross section
blunt tips from cutting or shaving.
Can the Age & Sex of an Individual Be
Determined from a Hair Sample?
AGE - cannot be determined from a hair
examination with certainty.
(except an infant)
SEX - can be determined if DNA
is found on the hair.
Is It Possible to Determine If Hair Was
Forcibly Removed from the Body?
Hair naturally falling off the body will
show a root without any follicular tissue.
A hair root with follicular tissue means
that the hair had been pulled out either
by another person or by brushing.
How Can We Individualize Human Hair?
DNA from the follicular tag can be
matched to one individual
FOLLICULAR TAG – a translucent piece
of tissue surrounding the hair’s shaft
near the root.
This is the best source of DNA in hair.
Collection & Preservation
of Hair Evidence
Hairs found at the crime scene are
compared to samples from the victim
and from the suspects
50 full-length hairs from all areas of the
scalp may be collected as samples
Use a piece of tape to collect and
package hair samples from a crime
scene
What causes gray hair?
• As you age, the natural production of pigment slows
down and your natural color loses its color strength.
• Doesn't happen to every hair at the same time, so the
contrast between the hair with no color and the hair that
still has some color causes it to look gray.
• So how gray your hair actually looks is determined by the
percentage of strands with no color vs. the pigmented
strands.
Root of Hair
• Provide the tools to produce hair and continue its
growth
• 3 Stages of Growth (different looking roots)
– Anagen -initial phase may last up to 6 years, root is
flame shaped
– Catagen –transition phase (2-3 weeks), root is
elongated
– Telogen –phase where hair naturally falls out of the
skin, root is club-shaped
• Hair analysis video