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Trace Evidence

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

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  1. Trace Evidence Hair NS2232 - Littlefield

  2. Trace Evidence--any small pieces of material, man-made or naturally occurring Most common examples: • Hair • Fiber NS2232 - Littlefield

  3. 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

  4. From hair one can determine: • Human or animal • Race • Origin • Manner in which hair was removed • Treated hair • Drugs ingested NS2232 - Littlefield

  5. Hair Structure

  6. Mosaic Pectinate Imbricate Petal Diamond petal Chevron Hair Cuticle Scale Types NS2232 - Littlefield

  7. Scale Types Chevron Mosaic

  8. Scale Types (cont) Diamond Petal Petal

  9. Scale Types (cont) Pectinate Imbricate

  10. Human Hair

  11. Human Hair

  12. Cat Hair

  13. Cow Hair

  14. Dog Hair

  15. Bat Hair

  16. Hair Structure

  17. Hair Cortex The cortex gives the hair its shape. It has two major characteristics: • Melanin • Cortical fusi NS2232 - Littlefield

  18. Hair Structure

  19. Hair Medulla Types • Continuous • Intermittent or interrupted • Fragmented • Absent--not present NS2232 - Littlefield

  20. Hair Medulla Patterns • Uniserial • Multiserial • Vacuolated • Lattice NS2232 - Littlefield

  21. Human medulla • Human medulla may be continuous, fragmented or absent.

  22. Rabbit medulla

  23. Double Medulla

  24. Medullary Index for human hair is generally less than 1/3. For animal hair, it is usually greater than 1/2. Medullary Index

  25. Hair Growth • Anagen--hair that is growing • Catagen--hair at rest • Telogen--hair that is dying NS2232 - Littlefield

  26. How/When Did It Leave? Anagen Telogen

  27. Ethnicity Asian Black Caucasian

  28. Cross-Sections Black Caucasian Asian

  29. Dyed Human Hair

  30. DNA • Mitochondrial • Nuclear NS2232 - Littlefield

  31. 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

  32. 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

  33. Buckling

  34. Razor Cut

  35. Egg Case

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