|Penkovsky during his trial|
Born in 1919 as the son of a White Army officer who died during the war against the Bolsheviks, Penkovsky followed in his father's footsteps and entered the Soviet army in 1939 as artillery officer. After the Second World War, he graduated from the Frunze Military Academy and joined the GRU (military intelligence) where he received intelligence training. Penkovsky was sent abroad under the cover of military attaché of the Russian Embassy to Turkey, to spy on Turkish and U.S. military installations and later received training in missile and rockets weaponry.
Problems with his superiors, apparently because of his father's past, affected his assignment in Turkey and later caused a planned assignment in India to be cancelled. These were probably the seeds for his disillusion in the Soviet system and his dislike for the politics of Nikita Krushchev.
In 1961, prior to leaving for London to set up a Soviet spy network, Penkovsky contacted British and American intelligence officers through a British businessman in Moscow. During his frequent travels to the West for his GRU missions, Penkovsky, now a double agent codenamed HERO and YOGA, met with CIA and MI-6 officers and underwent extensive debriefings. He also handed over numerous photos and documents to personnel of the British embassy to Moscow. His information gave the Western intelligence agencies a good view on the strength of the Soviet forces and provided evidence that Soviet military and technical capabilities were overestimated.
When the Soviets began deploying nuclear missiles in Cuba, at the doorstep of the United States, Penkovsky provided invaluable intelligence about the progress of the deployment of the missiles. During the subsequent Cuban Missile Crisis, his detailed information gave the Kennedy administration an important tactical and diplomatic advantage over the Soviets, making Penkovsky one of the few men that prevented a nuclear war and change the course of the Cold War.
During 1962, the KGB became aware of a mole in the Soviet intelligence community. It is assumed that either British MI-6 mole George Blake or NSA courier Jack Dunlap tipped off the Soviets, eventually leading them to Penkovsky. After an extensive surveillance, KGB officers arrested Oleg Penkovsky on 22 October 1962, just hours before U.S. president Kennedy would address the nation about the Soviet missiles on Cuban soil. GRU colonel Oleg Penkovsky was tried in may 1963. After his public trial, which was extensively covered in the media, he was found guilty to treason, sentenced to death and executed.
There's a featured story on Penkovsky on the CIA website, which also contains numerous numerous documents, related to the Penkovsky case. Below a Cold War Spies video, with interviews with former CIA Chief of Missile Division Sidney Graybeal, Penkovsky's CIA contact Joe Bulik and KGB interrogator Alexander Zagvozdin.