Bow Street runner FBI FBI agent Federal G-man MP Secret Service Sherlock Holmes T-man bailiff beadle beagle bear witness against betray betrayer blab blabber blabberer blabbermouth blow the whistle bound bailiff captain catchpole chief of police commissioner constable delator deputy deputy sheriff detective fed federal fink flic gendarme government man hotel detective house detective house dick inform against inform on informer inquiry agent inspector investigator lictor lieutenant mace-bearer marshal mounted policeman officer operative patrolman peace officer peach peacher plainclothesman police captain police commissioner police constable police detective police inspector police matron police officer police sergeant policeman policewoman portreeve private detective private investigator rat reeve revenuer roundsman sell out sergeant sergeant at arms sheriff sleuth snitch snitch on snitcher spy squeal squealer stool stool pigeon stoolie store detective superintendent talebearer tattle tattler tattletale tell on telltale testify against tipstaff tipstaves treasury agent trooper turn informer whistle-blower