While intelligence about FBI double agents is often classified, some high-profile cases involve prison sentences and publicity. Here are three of the deadliest and most destructive double agents we know about in FBI history:

1. Robert Hanssen

Robert Hanssen was a former FBI agent convicted of espionage in 2001 and sentenced to life in prison without the possibility of parole. He had been spying for the Soviet Union and later for Russia for more than 20 years and died in prison in June 2023. The FBI’s Eric O’Neill helped bring down Hanssen in an incredible operation outlined in True Spies’ podcast: Gray Suit & The Ghost.

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2. Earl Edwin Pitts ‍

Former FBI agent Earl Edwin Pitts was convicted of espionage in 1997 and sentenced to 27 years in prison. He had been spying for the Soviet Union and later for Russia for several years. Pitts shared classified information concerning FBI personnel, ongoing investigations, counterintelligence program strategies, and operational methodology. He was arrested for espionage at the FBI Academy in Quantico, Virginia on December 18, 1996. At the time of his arrest, Pitts was an instructor at the Academy.

3.  Richard W. Miller‍

Richard Miller was the first FBI agent to be convicted of espionage. On October 3, 1984, he was charged with providing classified FBI information to the USSR’s KGB spy agency. Miller was 47 years old at the time and a 20-year Bureau veteran. He worked within the FBI Los Angeles Division’s counterintelligence squad. On the same day, the FBI arrested Svetlana and Nikolai Ogorodnikov, two Soviet citizens with permanent resident status in the US. FBI Director William H. Webster called it “a very sad day for us”. Miller was sentenced to 20 years in prison and died in 2013.