US veteran counterspy Brian Kelley, who broke a code on how Moscow communicated with its agents and was mistakenly hounded later by the FBI, has died. Mr Kelley was 68.
The Washington Times said Mr Kelley died in his sleep of an apparent heart attack.
After years of service in US intelligence, Mr Kelley was hounded by the FBI on suspicion of being a mole for the KGB.
Their suspicion was found to be untrue but only after years of trying to get him to confess to being a KGB spy.
CIA spokesman Preston Golson said Mr Kelley kept the faith with his country and his colleagues.