Thank you...I am ashamed to tell you how many times I have watched that movie and still don’t understand everything that took place...It was the outside characters - the woman with the gun in the alley, the government men in the old building that came into the “casino” at the end etc., that I couldn’t get but that’s OK....don’t try to explain it to me...
OK I can’t resist because I love this movie SO much.
Salino - the waitress Redford shacks up with = hired assassin in Lonnegan’s gang.
The guy who shot Salino in the alley = a mobster Henry Gondorff hired to protect Hooker (Redford) and the guy who killed Salino before she could kill Hooker
FBI captain = works for Gondorff - part of the long con. We learn at the very end that Hooker was never going to snitch but needed to play along to get the pesky police detective to get Lonnegan out of the horse betting parlor to finish the sting.
Hope that helps!