Walker got a job in the communications office commanding the submarine force. In hindsight, the military realized it was a bad idea, leaving valuable intelligence in the hands of a youngster who'd previously stolen stuff and never got punished for it. Because in 1967, Walker figured out the solution to his money problems: He headed right to the Soviet Embassy and handed them some top secret documents. He worked out a deal to keep leaving goodies at prearranged locations, and he would go on working as a spy for the USSR for the next 18 years.
He'd make just a couple drop-offs a year, but it was enough to keep the bar running, buy a sports car, buy a boat, buy a damn airplane, and spend money in all all sorts of other ways that the KGB cautioned against in the name of discretion. The Navy never realized what he was doing, and we'd explain why that was, but that's classified. John's wife Barbara, on the other hand, did figure out something was up. She thought he might be having an affair (he was), so she searched through his things for phone numbers or secret photos. Instead, she found military documents, and when she confronted him about them, John said, "I'm a spy."
"Well, I am also sleeping with Janet, and I recruit for the KKK, but other than that, yeah, that's it."
At first, Barbara must have been into the idea, because she actually accompanied him on one of his drop-offs. But as so many male leads in prestige TV dramas know, these husband-wife alliances never last. He and Barbara eventually divorced. Still, she kept his secret, right up until she feared he might recruit their son as a spy next. So she phoned the FBI. Repeatedly. They didn't believe her, because she was generally drunk when she called.
Finally though, they did follow up on her tip, and they ended up nabbing John. They nabbed the couple's son Michael too -- she had waited too long, and John had recruited him -- but he went on to testify against his father. Once behind bars, John shared regrets over how he'd handled matters with his wife. "I should have assassinated her in the beginning," he said. "I should have put a f--king hole in her head."