You all have his address. Do something about it.
I've been researching this recently. Unfortunately, it is very difficult to prove fraud with an isolated case. The postal inspection service looks for patterns of fraud when evaluating cases. I'm not saying one should not pursue such avenues, but am just noting that it might be hard to prove.
That said, each time a person reports a fraud involving a person/address, it helps establish the pattern that might eventually allow them to take action against someone.