Yes, as I recall, shooting them was what identified them for me. Finding the one which didn't take damage was the quickest way to victory.
As for Stiletto's apparent uncaring, I think that was exaggerated to reinforce the impression that Casey knowing someone whom his father had influenced greatly had more of an impact on Casey than others might care to believe. (Funny wording, I know, but trying not to spoil anything on the off chance people don't yet know what happened.)
Edit: Just realised you said you finished Prophecy. So that would make two people. :/