I'm guessing you don't get a chance to blow him up? Either that, or he's in a bulletproof Cheetah or something... Or it fails the mission? 'cause that would be my first course of action.
Easily the hardest in the game, eh? Well fuck.
Just out of curiosity, how did you rate Martha's Mug Shot? I found that one to be annoying, but not particularly difficult now (I did it again at a friend's house).
I'd probably rate the hardest mission for me so far as "Death Row".