Find out if he has a trademark. At this location:
http://www.uspto.gov/
If he doesn't have a trademark on it, then pay the bastard back by trademarking it, and then going to an arbitrator, should only cost you 1400 US, and they will transfer the domain to you.
For arbitration go here:
http://www.arbforum.com
http://arbiter.wipo.int/domains
http://www.cpradr.org