Investigation Techniques are enabling law enforcement officers
to solve cases previously thought to be unsolvable.
The physical evidence would refer to any material items that
would be present on the crime scene.
The saliva on the stamp of a stalker's threatening letter or DNA
collected from the perspiration on a baseball cap discarded by a
rapist at one crime scene can be compared with DNA in the saliva
swabbed from the bite mark on a different rape victim.
Forensic Science that includes Forensic DNA & Serology, Drug
Chemistry and Forensic Toxicology. view
more links and a detailed
instrumentation here at the following:-