A friend of mine had a bunch of metal stolen several years ago: buckets of old brass fittings, irrigation pipe, etc. The deputy who took the report knew who did it and where they likely sold the stuff. He was as frustrated as my friend because he had arrested them before and they got out with a slap on the hand.
My friend went down to the scarp yard himself and when they weren't looking just walked back in and looked in the bins. Sure enough he recognized his stuff, but he had no way to prove it. He came back with the cop and were able to get the name of the seller, sure enough just who the cop said it was.
What can you do? They get away with it because it's just a property crime. Even if they are caught they get a slap on the hand and go right back to it. It just stinks because you feel violated. What makes someone think they can just take your property? I would rather give away $100 than have $10 stolen from me. I just don't understand thieves.
I think I told the above story here before, but for those that didn't see it, it had a bizarre ending. Here's the Rest of The Story, just a couple weeks after his stuff was stolen, same two guys:
http://www.highbeam.com/doc/1G1-169151566.html
That's a BAD way to go.