Nicholas Shadrin was a former Soviet navy officer who defected to the U.S. in 1959, sponsored by the U.S. Office of Naval Intelligence. In 1966 he was sent to the Defense Intelligence Agency; while there, a Soviet agent tried to recruit him. Working with the FBI, he became a double agent, feeding the Soviets misinformation. By 1975, the Soviets were convinced Shadrin was a double agent and abducted him, and he subsequently died in their custody. His disappearance remained a mystery to the U.S. intelligence community for years, until his fate was revealed in 1985.
Video on Nicholas Shadrin, intelligence professional dedicated to the defense of the U.S. May 2022.