Originally posted by Sandman
Way ahead of you... spent the better part of today chasing things down.
Good, and contact the FBI while you're at it. Their number is listed for ID theft, and they do take you seriously regardless of what others may say.
Legal issues aside, it probably was not a good thing that you posted the shipping address. The address sounds like another innocent person being had. Empty house for sale, nobody around to monitor the mail... Oldest form of "Safe Drop" in existence for crooks, drug dealers, and other n'ere do wells. Hell, since it's a cell phone, the FBI might even get DHS, or ICE in on it. All IRS will do is drag their feet for a couple years.
Mav has good advice. Listen to him.
I have to say I'm disappointed in some of the irresponsible replies here, like the "Burn the House down" one. For all you know, the house is more than likely vacant, and has been so for a while. You folks have any concept of how much trouble you can get into just by saying that, and something happens to the house? And do not think for a second that forums, emails and cell phones are not being monitored by the Feds... But you didn't hear it from me either.