Phishing for fun and profit....(by the good guy!!) (Score 1)

Since you have full access, I might dummy up a "automatic update" application and put it on the machine. First, have it configured to send you IP address, local peers, associated wireless SSIDs etc, all of which could be useful in localizing the system. Second, you can have it pop up a "free upgrade" window where they can get a replacement webcam/keyboard/whatever due to a manufacturing defect. All they have to do is fill out the "registration card" form the application offers them. Hopefully, they will give you all the information you need to track them down.