Synonyms and related words :
Bow Street runner, FBI, FBI agent, Federal, G-man, Internal Revenue Service, Secret Service, Sherlock Holmes, T-man, assessor, customhouse, customs, detective, exciseman, farmer, fed, hotel detective, house detective, house dick, inquiry agent, investigator, narc, operative, plainclothesman, police detective, private detective, private investigator, publican, sleuth, store detective, tax assessor, tax collector, tax farmer, taxer, taxman, treasury agent