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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?
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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 NS2232 - Littlefield
Mosaic Pectinate Imbricate Petal Diamond petal Chevron Hair Cuticle Scale Types NS2232 - Littlefield
Scale Types Chevron Mosaic
Scale Types (cont) Diamond Petal Petal
Scale Types (cont) Pectinate Imbricate
Hair Cortex The cortex gives the hair its shape. It has two major characteristics: • Melanin • Cortical fusi NS2232 - Littlefield
Hair Medulla Types • Continuous • Intermittent or interrupted • Fragmented • Absent--not present NS2232 - Littlefield
Hair Medulla Patterns • Uniserial • Multiserial • Vacuolated • Lattice NS2232 - Littlefield
Human medulla • Human medulla may be continuous, fragmented or absent.
Medullary Index for human hair is generally less than 1/3. For animal hair, it is usually greater than 1/2. Medullary Index
Hair Growth • Anagen--hair that is growing • Catagen--hair at rest • Telogen--hair that is dying NS2232 - Littlefield
How/When Did It Leave? Anagen Telogen
Ethnicity Asian Black Caucasian
Cross-Sections Black Caucasian Asian
DNA • Mitochondrial • Nuclear NS2232 - Littlefield
Collection of Hair Evidence • Questioned hairs • Known/Control Sample • 50 full-length hairs from all areas of scalp • 24 full-length pubic hairs NS2232 - Littlefield
Hair Toxicology Advantages: • 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