After President John F. Kennedy's assassination on Nov. 22, 1963, the U.S. government briefly suspected that the Soviet Union might have perpetrated the crime. Fears of Moscow's involvement were revived in early 1964 because of a convoluted counterintelligence (CI) episode involving CIA's legendary James Angleton and KGB defector Yuri Nosenko. No case in the Agency's history was more fraught with potential for conflict.

When news of President Kennedy's assassination reached CIA Headquarters, Richard Helms – then the head of CIA operations – recalled that "[w]e all went to battle stations over the possibility that this might be a plot – and who was pulling the strings."

Since assassin Lee Harvey Oswald was murdered two days later, officials speculated that Oswald may have been a Soviet or Cuban hit man. Agency officers ruled out that possibility in mid-December.

Nosenko Defects

But, suspicions of KGB involvement were revived in late January 1964 when Nosenko contacted the Agency and soon defected. (Two years earlier, Nosenko – a mid-level KGB officer – volunteered to work for the CIA as an agent in place.) At the January meeting, Nosenko made a startling disclosure: he had been assigned to watch Oswald during his defection to the Soviet Union (1959-1962). Nosenko said the KGB declined to work with Oswald after determining he was unstable.

Nosenko's surprise decision to defect and his news that Oswald was not a KGB asset seemed too convenient to Angleton and other Agency officials. Moreover, Nosenko contradicted Angleton's key source on the KGB, defector Anatoly Golitsyn.

Golitsyn asserted that the Soviets had a mole inside the CIA. Golitsyn also claimed that Nosenko was a disinformation agent sent both to discredit him and to hide Moscow's hand in President Kennedy's death.

Trying to Find the Truth

If Nosenko was found to be a dispatched agent, it would suggest that Moscow had ordered the murder of an American president – probably a casus belli for the United States. Consequently, Nosenko was detained for several years when it appeared to CIA officials that he might be hiding a Soviet role in the assassination.

With so many questions raised, senior Agency leaders knew it was essential to elicit the truth from Nosenko. Helms later said, "If it were shown that Oswald was acting as a Soviet agent when he shot President Kennedy, the consequences to the United States and to the world would have been staggering."

Despite being detained for more than three years, Nosenko never changed his story. Nosenko was eventually released and compensated.

Angleton’s Molehunt

Meanwhile, Angleton was compelled to find the mole inside the CIA, as asserted by Golitsyn. Along the way, this hunt damaged many Agency officers' careers and tarnished Angleton’s reputation.

Acting on Golitsyn's vague leads, Angleton did find a mole. But because he was not as senior or as damaging as Angleton had thought, and was no longer working for CIA, Angleton continued to search for the "primary mole" supposedly still inside Langley.

Along the way, 40 Agency officers were put on the suspect list and 14 were thoroughly investigated. Although innocent, all had their careers damaged by the "security stigma."

Angleton was fired in December 1974 amidst the "Family Jewels" scandal, and as details of the Nosenko case and the molehunt became widely known inside and outside the Agency, his theories and methods fell into disrepute.