Karl Koecher is one of only two known moles to have penetrated the CIA. Born in Czechoslovakia, he became a radio host and was frequently scrutinized by the Communist security forces for his satire that mocked the regime. Worried about his safety, Koecher decided to switch roles, and with the help of a friend joined the Czechoslovakian intelligence service in 1962. This, however, was not as dramatic of a change as it might appear. In the years before the Prague Spring, the intelligence bureau was filled with Czech nationalists highly critical of the Soviet imposed regime.

Because of his dissident past and English language skills, Koecher was selected to become a mole in the west. In 1965 he and his wife, Hanna Koecher , seemingly defected to the west, moving to the United States. Koecher became an American citizen in 1971. After many years as a sleeper he was hired by the CIA as a translator in 1973 due to his dissident credentials and skill in a number of Eastern European languages. He was given high level security clearance and given the job of translating documents handed over by CIA agents and transcripts of wiretaps and bugs. He quickly became one the USSR's best sources of information allowing them to find a number of leaks in their system.

In 1975, however, Koecher was summoned back to a meeting with KGB head of counter-intelligence, Oleg Kalugin. After testing Koecher, Kalugin argued that he was in fact a double agent and his information could not be trusted. Others in the intelligence service disagreed strongly with Kalugin's assessment. Koecher was thus not killed, but he was retired leaving the CIA for a post in academia.

Later a number of Soviet intelligence officials became convinced that it was Kalugin himself who was a double agent and that he had deliberately set out to destroy one of the KGB's best assets.

By the end of the 1970s Koecher was thus rehabilitated by the KGB. In 1980, with growing tensions due to the election of Ronald Reagan, Koecher was one of a number of agents reactivated. He returned to work part-time for the CIA. The FBI was on to him, however. To this day neither the FBI nor the CIA will reveal what alerted them to Koecher's treachery. Koecher and other KGB officials believe it was Kalugin.

The FBI apprehended Koecher and brought him, and soon after his wife, in for several days of questioning. Finally, Koecher agreed to become a double agent working for the Americans, provided that they agreed to grant him immunity from prosecution. This was done and Koecher made a full confession.

However, it was then decided that Koecher was not reliable enough to be a double agent and was likely to defect and return to Czechoslovakia to a hero's welcome. Thus on November 27, 1984, the day before they were scheduled to fly to Switzerland, Koecher and his wife were arrested in New York City and the arrest of the two agents was released to the media.

It soon emerged that the FBI had badly blundered. Koecher's confession was given only after he had been promised immunity, and was thus invalid. His wife had been denied access to a lawyer despite frequent requests for one. With little concrete evidence it appeared that Koecher had a good chance of being acquitted.

Not long after this became apparent Koecher was the victim of an attempted stabbing by an unnamed inmate while in prison. The inmate lunged at Koecher with a pair of scissors and would probably have severely wounded or killed him if not for the intervention of the then president of the Hell's Angels, who was in the cell next door to Koecher in the high security facility. The two had frequently conversed and grown friendly. Koecher thus escaped unharmed. The disappearance of his assailant after the attack has lead Koecher to accuse American security officials of trying to have him killed. The CIA and FBI deny this charge.

Koecher, worrying about his own safety, proposed that he be part of a prisoner exchange with the Soviets. The prosecutor’s office, concerned about the embarrassing chance of an acquittal, agreed. Thus in February of 1986, Koecher and his wife were part of a nine person exchange, of which the most prominent member was noted dissident Anatoly Shcharansky, who was released from the Gulags.

Koecher returned to the Czechoslovakia where he was lauded as a hero. The fall of communism has seen him fall from prominence and he continues to live in the Czech Republic in relative obscurity.