James Jesus Angleton was chief of CIA Counterintelligence from 1954 to 1975, and was significantly involved with ferreting out Soviet disinformation received by the CIA. He later became convinced that there was a KGB mole working inside the CIA and engaged in an intense search. There is debate whether this hunt for the mole was appropriate caution or was fruitless and destructive.
(From: Encyclopedia of Intelligence & Counterintelligence)
James Jesus Angleton, the CIA, and the Craft of Counterintelligence by 
