[Icy]

OK, best I can get is "wicked/villian before he himself is prosecuted." Is it meaning that the truly guilty party will try to accuse someone else to remove the suspicion from themselves?

It's used by the accused to rebuke the accuser and hint that they are trying to do what you just described. Sometimes the usage represents a genuine case while sometimes it is no more than a lie. It has little factual basis, but serves to remind the audience of what you just said with sarcasm/ridicule. It can also be used as a descriptive statement of factual events. <-- as how I used it.

Hmm, a little off-topic already.