John Walker Jr

He developed a production line of secrets that included war plans, technical manuals and operational orders. The KGB supplied him with a miniature Minox camera to photograph thousands of documents. John Lehman, US navy secretary in the Reagan administration, said Walker’s espionage would have resulted in a huge loss of American lives in the event of war with Russia.

His betrayal of his country places him in the same treacherous category as Klaus Fuchs, the German-born physicist who emigrated to Britain in the late 1930s and supplied Moscow with America’s atom bomb secrets, and Aldrich Ames, the veteran CIA officer, who gave the names of Russian agents to the KGB, leading to their arrest and execution.

Walker ran a family spying business. After he retired from the US navy in 1976, concerned that he was coming under suspicion by his superiors for security breaches, he recruited Arthur, his older brother, a retired naval lieutenant-commander, and Michael, his son, an active-duty seaman, to continue serving his controllers in Moscow. Jerry Whitworth, a radio specialist in the US navy, was also recruited.

A million secrets were passed, and all for money, estimated to be $1 million. There was never anything ideological about Walker’s spying career. He suffered from heavy debts after the failure of a bar business he had set up, and in 1976 he and Barbara, his wife, divorced. However, he did not take into his calculations that a woman scorned, especially one who had turned to alcohol for comfort, might eventually betray him. She tried on a number of occasions to warn the FBI that her ex-husband was a spy, but her drunken ramblings on the phone were initially ignored.

The authorities eventually started an investigation. In the early hours of May 20, 1985, Walker was staying in room 763 in a Maryland motel north of Washington DC. His routine of dropping off secrets in a grocery bag at one location and picking up cash at another had not gone according to plan. At 3.30am his phone rang and an excited male receptionist told him his van parked behind the motel had been damaged in a crash and advised him to come down immediately. He grabbed a .38 revolver and opened his door. Armed FBI agents were waiting for him.

John Anthony Walker was born in 1937 in Washington DC. His father, James Walker, was a Warner Brothers marketer before he lost his job and went bankrupt. His mother, Peggy, was an Italian-American. Walker, nicknamed “Smilin’ Jack”, went to a Catholic school and became an altar boy.

He joined the navy in 1955 as a radio operator, serving on an aircraft carrier, where he was awarded top secret cryptographic security clearance. He also qualified as a submariner. He met his wife, Barbara, in 1957, and they had three daughters — Margaret, Cynthia and Laura — in addition to their son Michael.

Over the next ten years he served on six warships, including two nuclear-weapons carrying strategic submarines. During one patrol on board a hunter-killer submarine in 1962, the boat’s mission was to spy on the Soviet port of Vladivostok. His naval record underlined his reliability, competence and future promise. But the long periods away from home put a strain on the family, and he decided to invest money in a piece of land in South Carolina where he built a bar, as a way of providing a job for his wife and an alternative for him when he left the navy. His hopes crashed, and with it, his solvency.

He turned to selling his country’s naval secrets in October 1967. He photocopied a number of documents at Atlantic Fleet Submarine Force HQ in Norfolk, Virginia, where he was working, jumped into his red MG sports car and drove to Washington. He parked and then calmly walked into the Soviet embassy and offered his documents and his services.

In the espionage world, it was a classic “walk-in”. The Russians thought it was a trap but when the KGB resident chief examined the documents, he recognised their importance: one was about US submarine movements, another was a National Security Agency paper listing the latest settings for a KL47 encryption machine used by the US Navy. The KGB station chief, Boris Solomatin, went down to see Walker, and so began a long and treacherous relationship.

The following year, Walker handed over the encryption key list for another machine called KW7. When North Korea seized an American spy ship, the USS Pueblo, which had a KW7 on board, the Russians helped themselves to a mass of material, and, with Walker’s code list, they were able to plot US navy ship movements with ease.

Walker’s downfall came when his wife became suspicious. The family’s money problems had mysteriously vanished. He claimed it was through moonlighting but she was convinced he was having an affair. Going through his belongings, she found a grocery bag stuffed with classified documents. She confronted him and he confessed, but she took no further action until much later, after they had divorced.

Walker’s daughter, Laura, testified at his trial after she revealed to the FBI he also tried to recruit her. She was then serving as a radio operator in the US army. Her father, she said, used emotional manipulation: “He’d tell you you were a failure, that you would never amount to anything in life. Then he would say, ‘Let me help you make a lot of money’.” She refused.

Walker pleaded guilty in a bargaining deal to limit the sentence for his son, who was also arrested. Walker was sentenced to life imprisonment. The rest of his spy ring also went to prison. He would have been eligible for release next year, but had throat cancer and was being treated at a federal prison medical centre in North Carolina.

John Walker Jr, American KGB spy, was born on July 28, 1937. He died on August 28, 2014, aged 77