Brian Kelley | Veteran counterspy, 68

Brian Kelley, 68, a veteran counterspy who broke a code on how Moscow communicated with its agents and was mistakenly hounded later by the FBI, died in his sleep of an apparent heart attack and was found Monday, his wife, Patricia, said.

Mr. Kelley spent 20 years with the Air Force Office of Special Investigations, doing counterintelligence work, until 1984, when he moved to the CIA. While working in the agency's counterintelligence office, Mr. Kelley figured out a method used by Moscow to secretly communicate with its agents. That led to the discovery of State Department diplomat Felix Bloch, a suspected spy meeting a KGB officer in Europe, but the investigation of Bloch was compromised.

"No one could figure out who would have tipped off the Russians," Mr. Kelley later told CBS's 60 Minutes. "We had it so tightly held at CIA that only about seven people knew, and they eliminated everybody but me."

When CIA counterintelligence officer Aldrich Ames was arrested as a spy for Moscow in 1994, the FBI began searching for a second mole and focused on Mr. Kelley because the Bloch probe had been compromised.

In August 1999, FBI agents questioned Mr. Kelley for hours in an effort to make him confess. Mr. Kelley refused and told the agents: "Your facts are wrong. Your conclusions are wrong. Your underlying hypothesis is wrong."

FBI agents continued to harass Mr. Kelley and his family for two years, sidelining his CIA career.

He eventually was cleared and went back to work with the CIA. He retired in 2006.

- AP