Finding my PPP's deceased parent..

Hi all! I spoke with one of my favorite PP's yesterday and he mentioned his father was deceased and when i asked him the details he got very sad and said he didn't know much himself. He also expressed a desire when he gets out to find where his father is buried so he can pay his respects. He doesn't speak to anyone on his father's side of the family and nobody in his OWN family knows any details in regards to his father's death. He thinks he knows what state he's buried in because he was in and out of prison there most of his life. Does anyone know any good websites where i can look up information on where someone is buried or when they may have died? I tried but nothing seems to be helpful and i'm hoping someone else has a idea i haven't thought of. Thanks =)