John A. Walker, the one-time Navy chief warrant officer who was convicted of masterminding a spy ring that provided the highest classified military secrets to the former Soviet Union, has died. Walker, 77, had been serving a life sentence in a federal prison in North Carolina. Walker was convicted in 1985 of providing the Soviet Union with secret codes and information for nearly 17 years. He had formed a spy ring that included his brother Arthur, son Michael, then a junior sailor, and a friend, Jerry Whitworth. Media reports say Walker was caught when his wife turned him in, after she learned he had tried to recruit their daughter to work for him. “The information passed by walker and his confederates would have been devastating to the U.S. had the nation gone to war with the Soviets,” the FBI stated on its Web site. No cause of death was released.