[blumer]

If you think you may have the IP address, is there any chance that whatever OS you have running on it will let you discretely log in remotely? Then you can drop some sort of homing beacon on for now so that if the criminal moves (likely, given it's a hotel, of course), you're not SOL.

[kordless]

Or make it make a sound like you are getting email every 30 seconds or so. Then go from door to door listening for it.