Trace Evidence

This essay Trace Evidence has a total of 1201 words and 5 pages.


Trace Evidence
Trace evidence is very important in forensic investigations. This category of evidence encompasses many
diverse types of microscopic materials as well as some examples that are easily visible to the naked eye.

The subject is broad and diverse because of the number of different types of evidence that are commonly
encountered. Trace evidence can be thought of as evidence occuring in sizes so small that it can be
transferred or exchanged between two surfaces without being noticed. Varieties of trace evidence can
include, but are not limited to: metal filings, glass fragments, feathers, food stains, building materials,
lubricants, fingernail scrapings, pollens and spores, cosmetics, plastic fragments, gunshot residue,
chemicals, paper fibers and sawdust, human and animal hairs, plant and vegetable fibers, blood and other
body fluids, asphalt or tar, vegetable fats and oils, dusts and other airborne particles, insulation, textile
fibers, soot, soils and mineral grains, and e!

xplosive residues.

Forensic scientists routinely come into contact with a relatively few number of these. They are: hair, glass,
paint, fibers, fingerprints, and flamable liquids. These will be covered more in-depth in this paper.

Edmond Locard, a French scientist and one of the early pioneers in forensic science believed strongly that
individuals could not enter an area without taking dust particles with them from the scene. This became
known as what is now called "Locard's Exchange Principle." This principle states that when two objects
come into contact with each other, each of the objects will leave particles of one on the other. It is this
principle that is the foundation of the forensic study of trace evidence.

Trace evidence examination is the examination and analysis of small particles in order to help establish a
link between a suspect and a crime scene or a suspect and the victim of a crime. These small particles
usually include such items as hair, paint, glass, and fibers. Although not considered "trace" items by
definition the many Crime Labs also examine and analyze such important evidence as flammables (in arson
investigations), fingerprints, footwear (shoeprints), and "fracture matches." Many also perform
examinations of automobile headlamps, taillights and speedometers.

The first category of trace evidence I will discuss is hair. Hair is examined grossly (with the naked eye),
and with both low power and high power microscopes to determine if questioned

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