DSi stolen, no concrete proof, wat do?

I had a Nintendo DSi console with Lego case attached, an 8GB SDHC card, a DS game (Wario-Ware DIY), and a bunch of dsiware dlc sitting next to me on a desk untouched for a week or two. Now my room's kind of cluttered with boxes and stuff so when I noticed it was gone it took a while to look everywhere because I initially thought it was just lost. However, this "friend" of mine who I only ever let in the house out of sympathy more than anything else visited 3 days in a row shortly before I noticed the disappearance of the DSi. He's stolen from me before, but only small toys when he was young, and quite frankly at first I didn't think he'd be stupid enough to take something as noticeable as this. The following few weeks me and my mother looked in every room of the house, even places I knew it wouldn't be, had the carpets up and all, just to isolate the chance that it's definitely been stolen and not just misplaced. I checked all my other games and systems, everything's still there except the DSi. I suppose it's my fault for going downstairs for a drink while he was leaving instead of following him to the door and forcing him to empty his pockets, but I prefer to give people the benefit of the doubt, and I refuse to accept responsibility for his breach of my trust. I know I hadn't left it anywhere because I always leave the case upstairs before I take it with me and that was gone too. I still have the receipts and proof of ownership for everything, but that won't do any good if it's been sold for £30 at GAME already. He is from a large family (15+ and counting), a chav mafia of sorts, so I can’t beat it out of him, and I don’t know what I can do. I’ve checked all of his family’s facebook pages for a “DSi Photos” album that gets created when you upload photos from a DSi, nothing, and I’ve sent him a message to come round my house which he ignored, and commented on his status to which he hasn’t replied. I now have problems communicating with him, because I don’t actually know where he lives to be precise, just the general area. So what, do I confront him on facebook, try repeatedly to get him to visit so I can weasel some sort of proof out of him, or phone the police to waste their time and tell them that I don’t know where the person who might have stolen my DSi lives? I will be willing to elaborate if that helps but I refuse to give up.