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Trace Evidence

Hair

NS2232 - Littlefield

Trace Evidence--any small pieces of material, man-made or naturally occurring

Most common examples: Hair Fiber

NS2232 - Littlefield

Questions for Trace Evidence

What is it?

Is it man-made or natural?

What is its source?

How common is it?

Can it be identified to a single

source?

NS2232 - Littlefield

From hair one can determine:

Human or animal Race Origin Manner in which hair was removed Treated hair Drugs ingested

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Hair Structure

Hair Cuticle Scale Types Mosaic Pectinate Imbricate Petal Diamond petal Chevron

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Scale Types

Mosaic Chevron

Scale Types (cont)

Petal Diamond Petal

Scale Types (cont)

Pectinate Imbricate

Human Hair

Human Hair

Cat Hair

Cow Hair

Dog Hair

Bat Hair

Hair Structure

Hair Cortex

The cortex gives the hair its shape.

It has two major characteristics: Melanin Cortical fusi

NS2232 - Littlefield

Hair Structure

Continuous

Intermittent or interrupted

Fragmented

Absent--not present

Hair Medulla Types

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Hair Medulla Patterns

Uniserial

Multiserial

Vacuolated

Lattice

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Human medulla

Human medulla may be continuous, fragmented or absent.

Rabbit medulla

Double Medulla

Medullary Index

Medullary Index for human hair is generally less than 1/3.

For animal hair, it is usually greater than 1/2.

Hair Growth

Anagen--hair that is growing Catagen--hair at rest Telogen--hair that is dying

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How/When Did It Leave?

                      

Telogen

Anagen

Ethnicity

BlackAsian

Caucasian

Cross-Sections

Caucasian

Black

Asian

Dyed Human Hair

DNA Mitochondrial Nuclear

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Collection of Hair Evidence

Questioned hairs Known/Control Sample

– 50 full-length hairs from all areas of scalp– 24 full-length pubic hairs

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Hair ToxicologyAdvantages:

– Easier to collect and store– Is externally available– Can provide information on the

individual’s history of drug use.

Collections must be taken from different locations on the body to get an accurate timeline.

NS2232 - Littlefield

Buckling

               

Razor Cut

Egg Case

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