All of the above posts are good advice, but since Tez summed it up so well, I've quoted her. I would also strongly suggest that you follow the three pronged action others have recommended: Police report (or call Watch Commander, at least, and take notes on what he says), CO report (Oh, man, that's going to hurt him ), and keep records.
Best wishes! :asian:
I knew some guys that were more afraid of their superiors finding out than anything the police were going to do to them.
This is the time to take full advantage of the civilian's ignorance of military ways. Something of this nature should normally go no higher than the guy's platoon commander. You should, therefore, try to address it at least at the battalion or regiment level. The pissed-off colonel will call the LtCol to find out why he's being bothered with this ****. The very pissed-off LtCol, having had his *** chewed out by the Col, will call the Major and ask why's he's being bothered with this ****. And so on down the line. As they say: **** rolls downhill. And if you do it right, it could be an avalanche by the time it hits your friend.