Remember each gang member's name and role. Who is missing?

You decide to go through each of the members who have already introduced themselves in the case in one way or another: Dangerous Dealer, weapons seller, classy guy. Heavy Bodyguard, hired muscle, intimidating. Silent Killer, leader of the gang, admittedly brilliant. That brings you to the last member, yet to show himself in the case: Courteous Scammer, master infiltrator, charming little pain in the rear. Just have to figure out where he fits into all this.