A South African naval officer, Commander Gerhardt was arrested by the Federal Bureau of Investigation in January 1983 while attending a mathematics course at Syracuse University and was flown to Pretoria, where he was convicted of treason and sentenced in December to life imprisonment. He had been a walk-in to the Soviet embassy in London in 1960, volunteering to sell NATO secrets while on attachment to the Royal Navy, and had been recruited by the GRU. At the height of his naval career, Gerhardt had commanded the Simonstown naval base near Cape Town.
His second wife, Ruth Johr, who was Swiss and supposedly had been provided by the GRU, was convicted of having acted as his courier and sentenced to 10 years.
The existence of a mole in South Africa had been suspected since the KGB illegal Yuri Loginov had been dispatched to the country, but he had been intercepted and arrested in 1967. At the time of his recruitment, Gerhardt, who claimed to have been motivated by the internment during World War II of his German father, had been married for eight years to an Englishwoman, Janet Coggin, with whom he had three children. In 1999 she wrote an account of her experiences, The Spy’s Wife, in which she claimed that she had refused her husband’s invitation to become a spy, too, and had divorced him before moving to Ireland.