Daniel,
I hunt interference sources on wireless networks and think it wouldn't be too much trouble to locate if you can get some basic info. If you have a directional antenna, is his signal coming from the same direction evry time? if so, he's probably not mobile. I use some specific equipment designed for direction finding, but if you can get a portable spectrum analyzer and a directional antenna, you can zero in on the general location pretty quickly. If it stops, next time, you go where you last saw it and continue. Let's say you determine the interference is west of your location. Depending on signal strength, guess how far you think it could be and head west with your directional gear. Stop every mile and recheck until you see it move north or south. At that point, assuming he's stationary, you are beginning to pass him. move in that direction if possible. Overshooting is fine as long as you can verify you get on the other side of him. The point is to create a circle of where he is and then move in from there. If may take a week of jumping in the car a few times, but once you get it down to a few square miles, you can pull the addresses of all of the licensed hams in the area. Chances are, it is a ham and I would start there.
It isn't as hard as you might think. I often start driving with an omni antenna and a spectrum analyzer. Once I get fairly close, I break out the directional antenna and drive a block, sweep the area, drive a block, etc until I get really close. At this point, it's sometimes helpful to employ attenuators. I use a 0-50dB adjustable which is usually fine. A band pass filter is helpful when you get close too, but not as practical at 2 meters.
If you find him, unless it's a young teenage punk, I wouldn't confront him, record him, the location, anything you can to identify, then call the FCC, or local sheriff may be helpful. I have found the FCC is very lenient on unintended interferers, but can be very harsh on those intentionally disrupting communications.
Good luck and keep us posted