I would likely go all out and begin by emailing some fake juicy pics to yourself from a fake account, and see if the user takes the bait (check the IP logs). if so, send another email from the same person, but this time attach some sort of spyware, that at the very least, turns on the webcam (tell me you have one built in!), installs a keylogger, installs some sort of URL logging software, etc; this guy will likely login to his own email from the machine, and with access to all of this I'd say you're likely to track him down. The only question would be whether the police would be willing to retrieve the laptop for you based on the evidence you've gathered. But your giant cousin Vinnie might love to do just that.