So DNA testing is a complete waste of time then ?
It depends on the case and circumstances. When contamination is a strong possibility the results are worthless, particularly if you can't establish it is sperm based or blood based both of which are much more useful than tiny amounts of DNA that can be skin based and simply be the result of contamination. Webster agreed the only DNA test that could determine whose blood was removed in 1985 and 1986 would be by testing that specific blood. Since none of that blood remained for testing there was nothing to test.
Testing the moderator knowing that it tested negative for blood was particularly pointless but even if blood had been present it still would not have provided any help at knowing whose blood was removed decades earlier.
DNA is most useful when:
1) blood based DNA of a victim is found in blood on someone (which indicates at the very least they were present when the victim was killed) or found on something the person owns such as a potential weapon, in their vehicle etc.
2) blood based DNA someone found on a victim
3) seamen based DNA found on someone raped
4) hair or skin based DNA of a victim found on someone and the person has no valid reason for the DNA to have been transferred by accident innocently
5) hair or skin based DNA found under a victim's nails when there is evidence the victim fought with the attacker and scratched him/her
6) skin or hair based DNA found on a victim and there is there is no way for the DNA to have been transferred by accident innocently.
7) saliva based DNA of someone found on a victim or something at a crime scene such as a glass or cigarette and no innocent manner in which such got there.
8 ) Any DNA evidence proving someone was killed in a particular location such as house or car belonging to someone and the body was moved.
9) DNA evidence that proves a particular account of how an event went down is false, this is in part covered by other points already but there could be instances where this happens other than the 8 circumstances above.
In the above instances DNA is in its prime and can implicate or exculpate.
It has limited use in circumstances other than these and its potential use varies widely under the circumstances. it is most useful in stranger killings because that is when any DNA regardless of whether hair, saliva etc has no chance of contamination except in the lab so the simply finding of DNA period is bad news for the killer.
