Introduction to Fibers

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Presentation transcript:

Fiber Analysis

Introduction to Fibers Trace evidence Class evidence Direct transfer: suspect ←→ victim Secondary transfer: source → suspect → victim 95% of fibers lost from crime scene within 24 hours

Forensic scientist determines: Type of fiber – Natural vs Synthetic Color How many of each kind – Locard’s Principle

Forensic scientist determines: Textile origin Multiple types of Fibers Transfers Type of crime

Fiber Evidence Collected by: Special vacuums (large areas) Sticky tape Forceps Tested by: Microscopy – polarizing light, infrared Burn test (large quantities only)

Fibers are spun into yarns that have specific characteristics Fibers may be natural or synthetic

Yarns are woven, with different patterns, into textiles

Natural Fibers Animal fibers (protein) Plant fibers (cellulose) Sheep – wool Goats – cashmere, mohair Rabbits – angora Caterpillar – silk Plant fibers (cellulose) Seed: cotton Stem: hemp (Cannabis), jute, flax (linen) Mineral fibers Fiberglass (glass) , asbestos (rock mineral)

WOOL COTTON FIBERGLASS

ASBESTOS FLAX JUTE

SILK HEMP

Synthetic (Man-made) Fibers Regenerated fibers (modified natural fibers) Rayon Synthetic polymer fibers Polyester Nylon Acrylic