Perhaps they knew, or had been told by their mysterious informant who seemed to know everything.

There would be no phone call from the mysterious informant.

He repeated the other details about the shipment of cocaine, as relayed to him by the mysterious informant the previous night.

As your mysterious informant has probably told you, I was brought up around here.

He speculated upon the identity and purpose of the mysterious informant who had called him up from Los Angeles.

They wanted this mysterious informant in Berlin, in person.

That night, Officer DiMarco is on his way home and meets with a mysterious informant.

The mysterious informant abruptly pushed open the door behind him.

Tom shone his pocket flashlight as they began prowling about, searching for signs of their mysterious informant.

During the mob war which had swept Chicago, the mysterious informant had been active.