Trace Evidence

Trace EvidenceCategoriesHair and fiber (often studied together as hairs often make fibers ex. Wool)Fire and explosive residuesGlassSoil

Fibers: NaturalCottonLinenHempWoolSilk

FLAX: with polarized lightMan made (Synthetic)More than half of common fibersPolyester and Nylon are most common

Cross- section viewSometimes manufacturer specificUnusual forms more significant forensically

How valuable is a fiber?How the dye is applied, absorbed, and fades more important than color itselfHow MANY fibers that match are consideredWHERE the fiber is found on the body can be significant

FABRICS:Which is more likely to leave transfer evidence?

Taffeta

Fiberglass

X New?

Worn in?

XFabric SourceIt is not possible to say positively that a fiber originated from a particular fabric. WHY?

The wide variety of fiber types, fiber colors, and fabric types can make fiber associations very significant.

Most common fibers of all?white cotton fibers and blue cotton fibers like those comprising blue jeans

Types of transferDirect transfer (primary transfer) or indirect transfer (secondary transfer)

Fiber Evidence: Assigning SignificanceMatching dyed synthetic fibers or dyed natural fibers can be very meaningful, whereas the matching of common fibers such as white cotton or blue denim cotton would be less significantWhen a fiber examiner matches a questioned fiber to a known item of clothing, there are only two possible explanations:

The fiber actually originated from the item of clothing, orThe fiber did not originate from the item of clothing.

Important pieces of evidence

fingerprintshair

fibersTissue/blood

fibers

Trapped tissue

Hair in hand of suspect/victimComparisonsThorough random samples should be taken from the head and pubic regions of a suspect(s) and victim(s). Twenty-five full-length hairs, pulled and combed from different areas of the head and pubic regions, are generally considered an adequate representation of an individual's hair characteristicsWeaponsTrace before fingerprints

???

ACBD

Animal hairCottonHuman hairNylon

One study.

Residue on hairAnalysis