You searched for: “informer
informant, informer
informant (in FOR muhnt) (noun)
An individual who discloses facts often in response to interrogation: Because Thomas had been an informant for the police, he was shunned by his neighbors.
informer (in FOR muhr) (noun)
An individual who discloses knowledge, facts, and details, usually about another individual, and who is typically paid for such information: The police informer was paid a large sum for the information leading to the arrest of the gang members.

In the mystery book that Mildred is reading, the informant for the police had also turned into an informer for the central government.

informer (s), informers (pl) (nouns)
This entry is located in the following unit: form-, -form, forma-, format- (page 9)