Their identity as law enforcement officers is hidden and they are assigned to investigate crimes and criminal acts unable to be "worked" by investigators openly identifiable as law officers. (i.e. - drugs - organized crime - biker gangs - smuggling - etc - etc)
They also are involved in crimes that are "victimless" in the classic sense that typically involves parties that both agree to participate in, such as drug dealing and prostitution. Sometimes it may involve facilitating activities that lead to criminal conduct. This can lead to a person accused of committing a crime to claim entrapment, that is they would not have committed the crime without the government's involvement. For more about this issue, see the related link below.
A sleeping spy is called an undercover agent.
The duration of Undercover Agent - film - is 1.08 hours.
Undercover Agent - film - was created on 1939-04-19.
Nationwide, the average annual income for an undercover police officer is $68,000. The average annual income for an undercover police officer in New York City is $93,000.
A spy.
Agent Undercover - 2008 SUSPENDED is rated/received certificates of: USA:PG-13
Undercover Agent - 1939 was released on: USA: 19 April 1939 UK: 10 July 1939
Undercover Agent - 1939 is rated/received certificates of: UK:U USA:Approved USA:Passed (National Board of Review)
So it could work undercover.
The army is used to protect their own country of war. Sometimes there's missions that even an undercover police agent can't handle, that's when the army comes in.
not all police but only some.
A spy, operative, undercover agent, sleeper, spook, mole.