Informant [noun]

The FBI deployed an undercover informant who posed as a member of Hamas, the Palestinian terrorist group, and offered to help the suspects obtain explosives and training.

They threatened to arrest him if he didn’t agree to become an informant.

Those authorities ultimately used an informant to weed out their resistance efforts.

The FBI said it became aware of the activity through social media and also relied on an informant to collect information from within the group.

When Aunt Ri heard that Farrar had fled the country, she pushed up her spectacles and looked reflectively at her informant.

He denied it at once, wanted to know the name of her informant, and finally laughed the whole matter out of her mind.

To himself, he could give no reason for establishing the identity of the smoking-compartment informant.

From any other informant I would not have accepted this statement as probable, still less as true.

So far as I could learn from my informant, the case was one of flagrant persecution, with no culpable occasion behind it.

My informant had never actually seen the white women, but he was absolutely certain of their existence.