I don't care how many I hate Mommy videos and I hate Larry emails, he has. Anna's dead. She was father-shopping for cripes sakes.
And there's TONS of evidence to match his DNA up with. That's why he doesn't want HIS DNA out.
And wasn't Barth the one that removed Howards cup from the witness desk? Maybe they didn't want his fingerprints to be taken either. OK, so maybe it was a styrofoam cup, but forensics experts probably have a way of getting fingerprints off of that too.