The Navy warrant officer John Anthony Walker, Jr. was convicted as a spy for the Soviet Union in 1987, and is serving a life sentence. The New York Times said he had been the most damaging spy in history, having helped the Soviets decipher over 200,000 encrypted naval messages. It wasn’t the polygraph that caught him, nor surveillance by U.S. counter-espionage officers. His wife Barbara turned him into the FBI. He was bragging about all the money he was making, but Barbara was his ex-wife and Walker was behind in alimony payments.