IIRC, he was accompanied by Mexican authorities and did not operate independently. I can't remember for sure and I have no way to check it at the moment, since I loaned the book to someone in my department.

One of the incidents was the Colorado Canyon shootings in 1988. Several Mexican boys fired at a rafting party in the Rio Grande from the Mexican side, so there were crime scenes on both sides of the river that had to be worked.

I can't remember the exact nature of the other incident but it seems like he went after a fugitive.

http://en.wikipedia.org/wiki/Joaquin_Jackson