Each person's DNA is unique to them, and only them; no one's DNA is an identical match to anyone else's. When someone commits a crime, whether it is rape, murder, etc. They quite often inadvertenly (unknowingly) leave their DNA at the crime scene, or on the victim. Example: If a woman is raped, then the perpetrator's DNA (semen, hair, skin cells, blood) can be matched to the rapist. If the rapist is caught, or if his DNA is already in the criminal data base, then his DNA can be matched to the DNA left on, or near the victim, thus resulting in his arrest, conviction and incarceration.
