society > law > law enforcement > police force or the police > political police > [noun] > secret service or police > member of secret police (3)
a person who conducts investigations on behalf of the government; (now) spec. (U.S.) a person who conducts criminal investigations and has arrest…
U.S. Also with capital initial. An officer of a U.S. federal government agency, esp. a law-enforcement agency such as the Federal Bureau of…