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NOVEMBER 13, 2012

NOVEMBER 13, 2012 STANDARD: SFS2b-Analyze the morphology and types of hair, fibers, soil and glass . EQ: What is the structure of hair fiber? Read the case study on pg363 ( blue book), pg 420 (orange), and write and answer the following questions.

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NOVEMBER 13, 2012

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  1. NOVEMBER 13, 2012 STANDARD: SFS2b-Analyze the morphology and types of hair, fibers, soil and glass. EQ: What is the structure of hair fiber? Read the case study on pg363 (blue book), pg 420 (orange), and write and answer the following questions. What happened to the “Central Park Jogger”? What evidence caused the boys to be convicted? What eventually happened to the boys and what caused that decision to be made?

  2. Chapter 10 Examination of Trace Evidence: Hair

  3. Microscopic Evidence and Its Analysis - HAIRS - Most frequently found evidence at the scene of a violent crime - Can provide link between criminal, victim, and crime scene - From hair, one can determine: 1. Human or Animal 2. Race 3. Origin 4. Manner of removal 5. Treated hair 6. Drugs ingested

  4. Microscopic Evidence and Its Analysis - HAIRS - Hair Morphology - Shaft: sticks out of the skin - Root: below epidermis - Follicle: structure from which it grows

  5. Microscopic Evidence and Its Analysis - HAIRS - Hair Morphology - Medulla - Cortex - Cuticle

  6. Two features that make hair a good subject for identification: Resistance to chemical decompostion Ability to retain features for a long time

  7. Microscopic Evidence and Its Analysis - HAIRS - Hair Morphology - CUTICLE - Formed by overlapping scales that always point toward the tip end of each hair

  8. Microscopic Evidence and Its Analysis - HAIRS - Hair Morphology - CUTICLE - Scale variations dependent on species Pectinate Imbricate Petal Diamond Petal Chevron Mosaic

  9. Microscopic Evidence and Its Analysis - HAIRS Imbricate - Hair Morphology Human Petal Cat Mosaic Dog

  10. Microscopic Evidence and Its Analysis - HAIRS Pectinate - Hair Morphology Diamond Petal Mouse Northern Fur Seal Rabbit Chevron

  11. Cuticle Visualization Scanning electron microscope Make a cast of its surface using clear nail polish or softened vinyl

  12. Medulla – central core(may be absent) Cortex – protein-rich structure around the medulla that contains pigment Hair Structure Hair is composed of three principal parts: Cuticle – outer coating composed of overlapping scales The structure of hair has been compared to that of a pencil with the medulla being the lead, the cortex being the wood and the cuticle being the paint on the outside. http://library.thinkquest.org/04oct/00206/lesson.htm#t_hair

  13. Microscopic Evidence and Its Analysis - HAIRS - Middle layer, made of spindle-shaped cells (keratin) aligned in a regular array, parallel to the length of the hair, consisting of: - Hair Morphology - CORTEX • Melanin: pigment granules that give hair its color - Points of forensic comparison – color, size, shape, distribution

  14. Microscopic Evidence and Its Analysis - HAIRS - canal-like, innermost layer of cells, variety of types and patterns - Hair Morphology - MEDULLA - 4 Types 1. Continuous: most animals, seldom humans 2. Interrupted (Discontinuous): human pubic hair, sometimes head hair 3. Fragmented: mostly human hair 4. Absent: human hair

  15. MEDULLARY INDEX Measure the diameter of the medulla relative to the diameter of the hair shaft: Humans= <1/3 Other Animals= ½ or >

  16. Microscopic Evidence and Its Analysis - HAIRS - Hair Morphology - MEDULLA - 5 Patterns 1. Amorphous: no specific pattern 2. Uniserial: small blocks in a row 3. Multiserial: several rows of blocks across 4. Vacuolated: uneven pattern 5. Lattice: circular patterns

  17. 3-2-1 3 Important Facts 2 Connections 1 Question

  18. THREE GROWTH PHASES OF THE ROOT: Anagen- initial growth (follicular tag-rich source of DNA)-flame shaped Catagen- transition stage (elongated) Telogen- final growth (club-shaped)

  19. Microscopic Evidence and Its Analysis

  20. 3 FEATURES IMPORTANT FOR HAIR ID: Scale structure Medullary index Medullary shape

  21. 7 characteristics that interest Criminalists: Matching color Length Diameter Presence or absence of medulla Distribution Shape Color intensity of pigment granules

  22. How fast does hair grow on average? 1cm per month

  23. Microscopic Evidence and Its Analysis - Root Characteristics: Removal Pulled Forcibly removed Shed - Tip Characteristics Burned Cut Razored Split

  24. Can you identify the animal hairs shown? A B C D G E F H I • Think About It … • In which samples are we viewing the cuticle? How do they compare? • (2) In which samples are we viewing the medulla? How do they compare? • (3) What characteristics can be used to identify hair samples?

  25. Can you identify the types of fibers shown? A B C D E F • Think About It … • Which samples are natural fibers? • (2) Which samples are synthetic fibers? • (3) What characteristics can be used to identify fiber samples?

  26. Answer Keys http://micro.magnet.fsu.edu/primer/techniques/polarized/gallery/images/humansmall.jpg

  27. Types of Animal Hairs - Key Cat Horse Pig Human A B C D G E F H I Deer Dog Rabbit Rat Human

  28. Types of Fibers - Key A B C Acrylic Yarn Cotton Yarn Nylon Rope D E F Polyester Yarn Rayon Rope Wool Yarn

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