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Fiber Analysis

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Characteristics

  • Class Evidence

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  • Trace Evidence

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  • Early collection is critical
    • 95% of all fibers will be lost within 24 hours of crime

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Fiber Transfer

  • Direct Transfer
    • Transfer from original source to another source

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  • Secondary Transfer
    • An already transferred fiber is transferred again to another source

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Sources

  • Clothing
  • Carpet
  • Furniture
  • Linens

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Types of Fibers

  • Natural Fibers

A. Animal fibers

      • Hair – Wool (sheep), cashmere (goat), angora (rabbit), camels, alpacas

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      • Fur – Usually removed and used with skin

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      • Webbing – silk (cocoon of caterpillars)

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B. Plant fibers

      • Seeds – cotton (found in seedpod)

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      • Fruits – coir (covering of coconuts)

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      • Stems – hemp and flax (linen)

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2. Synthetic (Man-made) Fibers

A. Modified Natural Fibers

      • Derived from plants
      • Rayon

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B. Synthetic polymer fibers

      • Completely man-made
      • Polyester, Nylon, Spandex

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Identification

  • Visual Observations
    • Color
    • Texture
  • Microscopic Observations
    • Striations
    • Adherent materials
    • Comparison with reference samples

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Identification continued

  • Chemically

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  • Burn Test

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  • Dye Test (white fibers)
    • Different types of fibers will turn different colors
    • Use chemical dyes or beverage products (coffee or kool-aid)