He's one of Granados men, I've killed all the others but for some reason I can't get a kill condition for him. When I do the favor for the kill condition it just says "unable to return favor for kill condition ".
I couldn't get one, either. However, I did get pretty lucky when he was attacking one of my compounds. I executed him with an unarmed execution, and it killed him permanently. So.. Although the kill order doesn't seem to be obtainable for some reason, he -is- still killable.