1. If its for Verizon, then it has a CDMA Chip in it. TMobile and AT&T use a GSM Network.. So even if you unlocked it, Its not compatible with the network..
2. If it is in fact stolen, and you KNOW it is stolen, you need to take it to the police, and turn your "Friend" in.. If you get caught with this Stolen phone on you, You will get charged with possession of stolen property. Blackberries can be worth a lot, so that could be a big crime..