Contamination

Contamination is the alteration or destruction of physical evidence. It is the process that takes peace when a subject comes into contact with the surroundings or the surrounding with the subject.

Contamination is cause by: chemical composition, leakage in envelope or container, evaporation, mixture, mingling of evidence and alterations of garmets.

Suspect and Comparison Samples are suspect materials that consists of stains, hair, fiber and other trace of gross evidence found in the presence of a known standard.

Comparison Material is a sample of material removed and submitted for the purpose of comparison to the suspect material.
Rape: Wet section of carpet/bed sheet then dry section.
Arson: Charred material with suspect material and a "clean" area.

Individual Characteristics:
Identified as originating with a particular person or source.

Class Characteristics:
Characteristics of physical evidence are common to a group of objects or persons, they may be termed, "class" regardless of how thoroughly examined, such evidence can be placed only into a broad category.
EX: hair, soil, glass gragments, tool marks, shoeprints.