Forensic’s Test #1 2nd semester: Hair

What are the functions Hair? (SA)

Regulates body temp

Decreases friction

Protects against sunlight

Act as a sense organ

How much hair are humans born with ? (TF/MC)

5 million

Human hair is… and it can provide.. (TF)

Human Hair is one of the most frequently found pieces of evidence at the scene of a violent crime

It can provide a link between the crime and the criminal

From hair one can (TF/SA)

if the hair is animal or human - see if its raw - origin of the location of the sources body - if it was forcibly removed - if it has been treated w/chemicals - if drugs have been ingested - sometimes DNA, mDNA (maternal)

Types of hair: (tf/MC)

In humans, hair varies from person to person, and varies depending on its location on a particular person

50 hairs are usually collected

Parts of the hair shaft (Matching to photos)

Cuticle- outside covering, made of overlapping scales

Cortex- inner layer made of keratin and is added w/pigment, also contains air sacs called cortical fusi

Medulla- inside layer running down the center of the cortex

The cuticle parts:

The scales on it point toward the tip of the hair

• Cornal

• Spinous

• Imbricate

Humans have imbricate scales

The Cortex parts/mechanisms

gives har its shape

Contains Melanin

Cortical fusion- air spaces, usually found near the root but might be found around the hair shaft

What are the types of Medulla (SA)

Interrupted, fragmented, continuous, stacked, and absent

Humans only have absent, continuous, or fragmented

Animal VS Human Characteristics of hair

Differences: The pattern of pigmentation, the medullary index, cudical type

Medullary index info:

Diameter of medulla/the diameter of the hair

The medullary index for human hair is generally less than 1/3, animal is greater than 1/2

Hair shape types

Round = straight , oval = curly, crescent moon = kinky

Anagen (MC)

hair that is actively growing; a lasting up to 5 years; approx. 1000 days (teen years)

Catagen

hair that is not growing; a resting phase

Telogen

hair that is dying/going to fall out; lasting 2-6 months

Hair grows… (MC)

grows at .5mm/day or 1cm/mo or ½ in/mo

Lost about 100hairs a day

5 types of hair comparison

color, length, diameter, distribution, shape and color

What happens when you bleach /dye your hair (MC)

Dyed hair has color in the cuticle and cortex

Bleaching hair removes pigment and gives yellow tint

DNA from hair

Root has nuclear DNA

Hair shaft has lot of mDNA

Hair examination and testing (tf)

• hair w/o follicle DNA and its nuclear DNA cannot provide individual evidence

• Hair can yield class evidence

• DNA is extracted and amplified using PCR

• DNA is profiled using an automated process

• MDNA can be used to establish a genetic relationship through the mothers side

• Suspects can be excluded if their mDNA is not consistent w/ the crime scene mDNA

Collection of Hair: must be…

questioned hair must be accompanied by an adequate # of control samples

• from victim

• From possible suspects

• From others who may have disposers hair @ the scene

Control sample must (MC)

50 full length hairs from all areas of the scalp, 24 full length pubic hairs

who will collect hair from the dead and who gets the hair from the living? (MC)

If dead, the corners job to get the hair, CSA will collect from the living

Hair toxicology: advantages

Easy to collect and store, its externally available, can prove info of the individual (history of drug use or poisoning)

Collectors must get hair from different parts of the body to get an accurate timeline

Exemplar

Term used to describe a sample of known orgin

False positive

a test result that comes out positive when it should not

Gas chromatography

A meathod of separating chemicals to establish their properties

Keratin

A type of rigorous protein tha t makes u the majority of the cortex of the hair

Melanin Granules

Particles of pigment found in the cortex of a hair

Metabolite

A substance made or used when the body break down food, drugs, or chemicals or its own tissue

Morphology

The study of structure and shape of organic organisms

Polymer

A long chain molecular made up of preps eating structures called monomers

undulated

Slight waviness; wavy form of the hair