Bought a stolen iPhone? What can I do?

So yeah. I got screwed lols. I bought an iPhone 5 today around 6PM, and when I got home (10pm) I noticed a text stating he wanted to report his phone as STOLEN to a friend. He must have forgotten to delete it after giving me the phone, there's also what looks like a number on the text.

I have right now with me: A screenshot copy of his original craiglist AD posting (with time and date), screen shot of all of our text exchanges, where he texts me his home address and what time we were meeting at, and the original receipt of the iPhone w/ matching IMEI with the actual phone. It also has his ACC # and the Buyer's name and address (although it doesn't match with the address he gave me, I assume it's either a fake or a relative.)

Should I go to T-mobile and explain what happened? Could they prevent him from filing an insurance claim if I get there before he does? Would they even care? I was thinking about going to the Police station and presenting my documents but I'm not sure if they'll even care. My last option would be to try to resell it, noting it is blacklisted…

Added (1). Well it's not stolen ''yet'' because I called T-mobile while I was getting a copy of the receipt. And checked with them. They told me it was clean. So I'm hoping I can get to T-mobile and show them the text message I found indicating he was going to report it stolen soon PLUS the receipt+ text docs indicating I bought it from him? Dunno how it will fall out though

If you try to resell then you are guilty of dealing in stolen property.

Take all the evidence to the police. They can do an investigation. Since T-mobile was not involved in the sale, I do not think that they will do anything for you. The police will probably contact them to exchange information.