26 January 1983
The South African government announced at a special press conference that a senior South African naval officer, Commodore Dieter Gerhardt and his second wife, Ruth, had been detained for questioning in connection with alleged espionage. Gerhardt was commanding officer at the strategically important Simonstown naval base. They were jailed in December 1983 after being convicted of spying for the Soviet Union.
References

Kalley, J.A.; Schoeman, E. & Andor, L.E. (eds) (1999). Southern African Political History: a chronology of key political events from independence to mid-1997, Westport: Greenwood.|O'Malley, P., Pre-Transition 1983, from The O'Malley Archives, [online], Available at www.nelsonmandela.org [Accessed: 07 January 2014]