Tony Gallano appears in all of one scene, but his name is mentioned elsewhere, and he's clearly established as the big fish in The Syndicate. He's the power behind his cousin Salvatore Mistretta; he has influence over James Cummings, forcing him to deal with Mistretta's hijacked heroin shipment by reminding him of the deal they made years ago; and even Mitchell establishes getting a firm lead to Gallano as one of his objectives, telling this to Cummings' face. Yet, by the end of the movie, Mistretta and his henchmen are dead, as are Cummings and Benton, thus wiping out any potential witness against Gallano. Oh, yeah, Walter Deaney's dead too, and the FBI was looking into his criminal connections (which included Cummings, and thus implied to include Gallano as well, and if Mitchell hadn't been so obsessed with Deaney killing that burglar, he might've stumbled upon that one). One could wonder if leaving Gallano in play could've been a Sequel Hook, a case of What Happened to the Mouse?, or a simple case of They Just Didn't Care... but, since Mitchell 2 never did get made, it's hard to tell at this point.
When Deaney guns down the burglar he's trapped, wouldn't that leave traces of blood in the environment? He also frames the robber with his gun, which should surely be covered in his fingerprints - and as Mitchell finds, none of the other guns were loaded, so what did Deaney use to kill him? It doesn't add up. I mean, I understand that Deaney is taken off Mitchell's hands because of the Federal investigation into him, but.. Surely there'd be evidence there? Enough for the FBI to come in and stop him?