Answer:
you could ask stuff like did 1 person or a team examinant it because if 1 did it could be a false because his a dirty cop or person feeling got in the way and really it depends on the evidence if its a piece of hair at a grocery store before a muder then the lawyer could say he could of got grocery's before the muder even happens
but lets say the find his blood the prosecutor could say the muder suspect tried to fight the attacker and lost and the defendant dose not have much he could do
finale if a muder took place in a area people cant go and a hair or blood of the suspect the defendant could try to go from muder to trespassing with manslaughter or self defense or maby if its a very very very good lawer they could try for the person tryed to Assault the suspet and he had nowere so run so he jumped the fence and had to fight the jon/jane doe(if u dont no what that means it means a dead person that we dont no the name of) and won
hope this helps but the main thing is it depends on were are what they find