If you've been following along at home, this might sound a little like a rerun of a syndicated tv series. A bounty hunter, trying to bring in fugitives, while being a fugitive himself.
In the case of Duane Lee Chapman (warning, audio clip of "who let the dog out" plays repeatedly), it's the real thing. While capturing Andrew Luster in Mexico recently, he broke that Country's law. It's illegal to be a bounty hunter in Mexico.
This last Monday, instead of appearing in front of a Mexican judge, which is a weekly condition of his bail, Dog Chapman was busy picking up the bounty for the capture of Andrew Luster. The failure to appear now makes him a fugitive.
A Findlaw article on The Perils of Bounty Hunting offer an interesting and informative look at extradition in North America and the difficulties in chasing someone across national borders.