plainclothesman
Unmarked police officer
A plainclothesman is a police officer or detective who wears ordinary street clothes rather than a uniform while on duty, typically for surveillance or undercover work: A plainclothesman followed the suspect into the bar.
The term is dated; plainclothes officer is now more common.
Private investigator
- gumshoeInformal term for detective
- investigatorOne who examines evidence
- inspectorOfficial quality checker
- detectiveProfessional crime investigator
constable · sergeant · officer · policeman · lawman · cop · patrolman · flatfoot
Prolonged covert observation
- tailRear animal appendage
- shadowingFollowing to observe
- observationAttentive watching or remark
- monitoringOngoing observation of something
watching · tracking · eavesdropping · wiretap · bugging · snooping · binoculars · unmarked car
Avoiding notice by conforming
- incognitoWith identity concealed
- anonymousOf unknown origin
- unassumingNot making claims
- nondescriptWithout distinguishing qualities
inconspicuous · unmarked · cover · alias · assumed identity · low-profile · camouflage · conceal
Intentionally concealed
- infiltrateEnter secretly to observe
- informantOne who provides intelligence
- moleSubterranean insectivore
- insiderOne with confidential access
asset · sleeper · sting operation · bust · narcotics · vice squad · decoy · entrapment
sleuth
Private investigator
- gumshoeInformal term for detective
- investigatorOne who examines evidence
- inspectorOfficial quality checker
detective · constable · sergeant · officer · policeman · lawman · cop · patrolman · flatfoot · peeper
stakeout
Prolonged covert observation
- tailRear animal appendage
- shadowingFollowing to observe
- observationAttentive watching or remark
monitoring · watching · tracking · eavesdropping · wiretap · bugging · snooping · binoculars · unmarked car · lookout
blending in
Avoiding notice by conforming
- incognitoWith identity concealed
- anonymousOf unknown origin
- unassumingNot making claims
nondescript · inconspicuous · unmarked · cover · alias · assumed identity · low-profile · camouflage · conceal · facade
covert
Intentionally concealed
- infiltrateEnter secretly to observe
- informantOne who provides intelligence
- moleSubterranean insectivore
insider · asset · sleeper · sting operation · bust · narcotics · vice squad · decoy · entrapment · cover story
evidence
Facts supporting truth
- cluesHints toward answers
- interrogationFormal, probing examination
- witnessOne who attests
testimony · alibi · forensics · crime scene · case file · deduction · suspect · culprit · motive · arrest
plainclothesmanbeat cop
Officer assigned regular route
traffic cop · mounted police · patrolman · patrol officer · uniform
plainclothesmanpatrol officer
Uniformed law enforcer
beat cop · beat officer · foot patrol · community police officer · street patrol