Replying to Roommate stole my skis but no proof

So I was in a pretty great living situation with 3 other guys and 1 other girl (total of 5 in the house). It was awesome but the girl moved out (she was dating one of the guys and they broke up) and another guy moved in let's call him bob.

Since Bob moved in stuff has been disapearing and although no one has proof that he stole their shit we all are pretty sure it is him. Additionally he lost his job or got injured and had workers comp for a bit but in the last 2 months or so he has been fine and healthy (he wasn't even really injured to begin with just a sore shoulder). Which brings to mind how the fuck is he getting his money (huge reason why we really think that he is stealing shit as he is only one without a job). Then I went skiing this weekend and was gone from Friday to Sunday and forgot to lock my room.... My extra pair of skis was stolen out of my room and is now gone. I still don't have definite proof that it was him but obviously pretty sure its this asshole Bob. Do I call some friends up and beat the shit out of him... I called some pawn shops to see if they had found them and have been checking craigslist but no luck.

Luckily I'm moving out soon (about 40 days). Has anyone else had issues with roommates stealing shit and what did you do?