I'm most amused by the way they find evidence, claim it's significant, then discard it entirely once their theory falls apart. Just last week, the fact that Ivins had taken leave for the entire day before the anthrax was mailed was another smoking gun, proof that he had done the deed. But now that we DFHs have proved he couldn't have been mailing the anthrax at that time, then that piece of evidence is discarded entirely. It seems they don't want to entertain the possibility he was doing something else--perhaps meeting with someone, but not driving to Princeton. Similarly, lie detector tests were critical, until they discovered their main culprit passed his.
In other words, they're still making it up as they go along, and they still don't have a solid case that Ivins was the sole culprit.