I can think of no way for you to find out his crime, sentence, or release date except from him. The prison won't give out this information. If you know his family, you could maybe ask them. If you know that he was on parole and know which county, you can TRY the parole department, but I honestly don't think anyone will tell you anything since you are not 'related' any longer.
Maybe you can try writing him and see if he will tell you. Use a PO Box and not your home address, or course. Good luck.