What is secondary transfer – in forensic science

When trace evidence is transferred from one place (the source) to another (the recipient), that evidence may be transferred again. This can complicate the interpretation of transfer evidence Such as hairs, fibers, dust, and soil, which by their nature move easily. For example, if a burglar breaks into a home in which a cat lives, he or she will likely get cat hair on his or her clothing, since cat hair clings to fabric. The burglar may then leave the residence and sit in a car, depositing a portion of the cat hair in the car. This is a secondary transfer, which can lead to subsequent transfer. If, at some later time, a different person uses the car and gets the hair on him, a tertiary transfer has occurred. Consequently, transfer and trace evidence found on a person or a body reflect his or her most recent environment. The more time that passes after contact, the more trace evidence is likely to be lost.