Okay. Trace evidence is what is left behind when a material or a person made contact, so that can be footprints, fingerprints, soil samples, hair, fibers, or DNA. In our lab, what we refer to as a trace case, is something that the biologist doesn't actually examine, I don't actually test it, but I would save samples to be tested for DNA.
Some examples of this are, urn, like a swab taken from the steering wheel of a recovered stolen vehicle where it isn't blood, you are trying to find out who stole the car, who was driving the car.
It could be a shirt left behind from a robbery, so you would swab that for DNA, or a knife from a domestic assault. You wanted to know who was actually holding the knife, so you would swab it for user DNA.
So those are the kind of things that we consider trace. Where it is not actually a body fluid that we are testing for, but we think that there might be DNA left behind. And usually what this is is from allele cells or skin cells.