He worked for the police/government as a paid 'informer'. [='informant']
(..) about the rest of your organisation. What do you mean by that, Mr. Sosa? I'm taIking about Omar Suarez. This garbage was recognised by my associate at Iunch... He was an informer for the poIice. SOSA: He put Vito DuvaI and NeIIo and Gino Ramos away for Iife. chivato Let's get this straight now. (..)1983 Scarface