Federal Bureau of Investigation

The Federal Bureau of Investigation (FBI) is the primary investigative arm of the United States Department of Justice, serving as both a federal criminal investigative body and a domestic intelligence agency. The FBI has investigative jurisdiction over violations of more than 200 categories of federal crimes.

The Departed
In the 2006 crime drama film The Departed, Irish-American crime boss Frank Costello was secretly an informant for the FBI. This is in keeping with the real world mobster James Joseph "Whitey" Bulger, whom the character of Frank Costello was based on. Costello and his cronies embarked upon a major sale of microprocessors with a Chinese cartel. The police raided the site and everything erupted into gunfire. As Costello attempted to escape, he ran into one of his trusted undercover agents, Colin Sullivan. When Costello confessed to being an informant for the Feds, Sullivan, feeling betrayed, shot him dead.