Bow Street runner
FBI
FBI agent
Federal
G-man
Secret Service
Sherlock
Sherlock Holmes
T-man
detective
dick
fed
hawkshaw
hotel detective
house detective
house dick
inquiry agent
investigator
narc
operative
police detective
private detective
private investigator
revenuer
sleuth
store detective
tec
treasury agent
bitching
blasé
day-laborer
novelization
somebody