There are things that can be done to get the guy to "show up" on the day of the hit. Firstly, you assign him to the job on that day, not before -- an old trick of clever ringleaders of conspiracies. The other aspect of my little theory is that Rocco is given a Pentangelli type deal. "You have to die, now there are two ways we can do this: Neri blows your head off right now, or, you do me this 'service' (kill Roth), and in exchange . . . ." Now what is the "in exchange"? Here I admit I'm really speculating, but perhaps not too wildly: wouldn't Rocco have had a family, like Pentangelli did?
I'm rereading the novel after not having gone through it cover to cover for a long while, and I found the passage I was looking for: Rocco does have a wife and children (p. 105 of the hardcover 1st edition).
