Related Clues:

• Busters, at times
• Some enemies of the state
• M's men
• Government agents, briefly
• Secret observers
• Works in intelligence
• U.S. attorneys, e.g.
• Law-enforcement officers
• Mob foes
• Some undercover cops
• Gangsters' foes
• G-men, e.g.
• Mob fighters
• Ness' crew
• U.S. agents