hawkshaw

a person not on the police force who investigates criminal or illicit activity or searches for missing persons the firm hired a hawkshaw to find out who was fencing stock from their warehouse Synonyms dick, gumshoe, detective, investigator, operative, private detective, private eye, private investigator, shamus [slang], sherlock, sleuth, sleuthhoundRelated Words shadow, tail, tracer, tracker; fed, Federal, G-man, narc (or nark) [slang], plainclothesman