Ok real advice time. As others have said, confront him about it. He may come clean but he may also deny it, in which case I would suggest cutting ties. Whatever he does, he has a problem and he needs to be talked to about it. Who knows if the behavior will grow to include larger forms of theft? Do you really want to be so close with someone who knowingly steals from his peers?
I've dealt with all kinds of problematic friends, from manipulators to bribers to leeches to attention seekers. The worst thing you can do is let their behavior go unnoticed. What you say in your conversation is completely up to you, but you must talk to him about it.








