How old/naieve are you? Do you still buy the "oh I was drunk I don't remember anything from last night" line? Have you ever been tanked? Do you still remember enough from the night before? I think people accept that lie because they want to be able to use it too to excuse their potentially bad behavior in the future.
The only thing I would have done differently is not let him know the cops were called the 2nd time so they could catch him in the act (best case threatening your physical safety, worst case public intoxication).