Related Clues:

• Lt. Columbo et al.
• P.I.'s
• Clue hunters, slangily
• Hired sleuths, slangily
• They follow trails
• Hammer and Spade
• Spade and Queen, e.g.
• Private eyes
• Case workers
• Professional snoops
• Private investigators, for short
• Detectives (Sl.)
• Holmes and Chan, for two
• Investigators
• Warshawski and Millhone