This is an intriguing question that popped into my head last night; were the Death Eaters aware that Peter was on their side during the first war?
If they were, does that mean they were possibly aware of Sirius' innocence? Or would they have assumed Sirius killed Peter as revenge for being the traitor, so he was still guilty?
Or were they not privy to the information that Peter was a traitor?
The fact that none of them appear to have an issue with Peter during the events in the graveyard in GOF makes me think they knew he was on their side, but I'm not convinced.