Walker graduated from high school but did not attend college. He enlisted in the navy in 1965 and was trained in electronic communications. By the date of his retirement in 1976, he had attained the rank of chief warrant officer. He served tours of duty on nuclear-powered submarines and worked shore assignments in San Diego, Norfolk, and Charleston. In the fall of 1967 he contacted the Soviet embassy in Washington, D.C., and in return for appropriate compensation offered his services to the KGB. For eighteen years he delivered to the Soviets Navy cryptological materials, including secret codes, key lists, and manuals on the internal operations of U.S. cryptographic equipment. Former KGB Major General Oleg Kalugin has estimated that Walker was paid at least $1 million during his espionage career.
Walker enjoyed the considerable income that spying offered. Thus, upon retirement he found it necessary to recruit agents to provide him with the desired information. Walker's brother, Arthur, was a retired naval lieutenant commander and worked for the VSE (Value Systems Engineering) Corporation, which provided services to the navy. Arthur was able to provide his brother with material sought by the Soviets. John Walker's son Michael enlisted in the navy in December 1982. After an assignment on the U.S. aircraft carrier Nimitz in January 1984, he too became a source for secret material. Michael was placed in charge of the burn bag and could easily look for valuable documents on their way to destruction. He hid the selected material aboard ship until it could be delivered to his father. Perhaps John Walker's most valuable agent was not a family member but rather a former colleague and a senior chief radioman, Jerry Whitworth. During 1975–1979, Whitworth secured for Walker a wide range of secret material in cryptology. Whitworth's spying income was estimated to be about $330,000.
John Walker was an unscrupulous person, an accomplished liar, a heavy drinker, and a womanizer. His former wife, Barbara Crowley Walker, knew of his spying activity. Finally disenchanted by his corrupt behavior, she reported him to the Federal Bureau of Investigation in November 1984. Walker was placed under surveillance and was finally arrested while servicing a dead-drop zone in a rural area near Washington, D.C. His spy ring quickly unraveled upon his arrest. Walker and son Michael turned against Whitworth and bargained for a lighter sentence for Michael. Whitworth and Arthur Walker were left to the mercy of a judge and jury. On 7 November 1986, Michael Walker received a sentence of 25 years in prison. He was released on parole on 17 February 2000. Whitworth was given the harshest sentence: 365 years in prison and a $410,000 fine. Arthur Walker received life imprisonment coupled with a $250,000 fine. John Walker, the prime culprit and spy mastermind, received a life sentence.
Earley, Pete. Family of Spies: Inside the John Walker Spy Ring. New York: Bantam, 1989.; Hunter, Robert W., with Lynn Dean Hunter. Spy Hunter: Inside the FBI Investigation of the Walker Espionage Case. Annapolis, MD: Naval Institute Press, 1999.; Kneece, Jack. Family Treason: The Walker Spy Case. Briarcliff Manor, NY: Stein and Day, 1986.