Fiber Transfer Activity

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Presentation transcript:

Fiber Transfer Activity

Rub your sleeve against your neighbor’s sleeve Rub your sleeve against your neighbor’s sleeve. Then answer the following questions: Can fibers from one sleeve be detected on the other? Do hand lenses or masking tape aid the investigation? How?

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 Color How many of each kind Textile origin Multiple 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 Yarns are woven, with different patterns, into textiles Fibers may be natural or synthetic

Fiber Classification (Use textbook p. 81-84) Natural Fibers: (List the different types and examples of each) Synthetic Fibers: (List the different types and examples of each)

Natural Fibers Animal fibers (protein) Plant fibers (cellulose) Sheep – wool Goats – cashmere, mohair Rabbits – angora Caterpillar – silk Plant fibers (cellulose) Seed: cotton Fruit: coir (coconut) Stem: hemp (Cannabis), jute, flax (linen) Leaf: manila, sisal 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 Celanese Capron Synthetic polymer fibers Polyester Nylon Acrylic Olefins