Well to all intents and purposes it does prove a lack of involvement. Without it you have no proof. No physical evidence, no eye witnesses, no fingerprints, no videos - nothing.
No, it does not. Especially when you have suspects saying shit like, "I just held her legs" and " I just felt her tits".
That you can seriously claim that lack of dna means it proves a lack of involvement, you are either delusional or lying.
Query: Maybe you will answer this. None of the other libs will.
You are walking in the park one night, and happen upon a rape taking place.
Do you,
a. Say to yourself, "wow, nice tits. This is a great chance to feel them, while the woman is distracted with being raped" and then grope her?
or
b. other.?
Because scenario A, is the DEFENSE of one of your heroes in this story.