Get yourself a nice legal notepad. Write down douchebag's name and address. Write down dates, times, where exactly it took place. Get your girlfriend's story straight (i.e. why they were where they were when this went down, what happened that led up to this taking place, conversation topic, who else knows about his drug posessions).

Get names of other witnesses that she might know. Ask her how they know this guy. Write everything down so you don't forget or leave out a detail.

Oh, BTW Chris.....

Get all of this info from your girlfriend and only your girlfriend. Don't go doing it yourself or let her do anything. This is what police and detectives do. Asking around with other people or trying some setup trick on your own can:

1. Put you and/or her in danger

2. Jeopardize the legalities of your case.