Sorry to hear about that man!
I had a similar thing happen to me a few years ago, out of my car though. Stole CD player, 20 some CD's, amp (which I had JUST burnt up - and was going to replace, but got a laugh outta that one) 1 out of 2 speakers in the front (only one??? - don't know why) and bent my back seat all to hell, trying to get at my subs/amp/crossover/etc in the trunk. (never got through though) First thing I did, besides scream four letter words at 5:00am, was phone the cops. I suspected the neighbors across the street, as it was some kind of half-way house for teens, and they pretty much seemed to do as they please, at all hours of the day/night. Also had a helping hand in me MOVING OUT of the neighborhood.
They didn't give a rat's ass, as stated above. They offered to dust the car for finger prints - but what I wanted was immunity from prosecution after I gave the neighbors an intimate look of the car's tire iron, (across the head) the car's trunk (to transport) and the city's beautiful lake (to dispose)!!!!
I wish your friend all the best in getting something done about his situation.
EDIT: Oh yes, and I am NOW a firm believer of not blasting the stereo in your own neighborhood! Wait a few blocks, and then give 'er. That was one of the reasons for what happened to me above - the punks sat outside and seen me coming and going.