Avraham Marek Klingberg (7 October 1918 – 30 November 2015), known as Marcus Klingberg (Hebrew: מרקוס קלינגברג), was a Polish-born, Israeli epidemiologist and the highest ranking Soviet spy ever uncovered in Israel. Klingberg made major contributions in the fields of infectious and noninfectious disease epidemiology and military medicine, but he is most widely known for passing intelligence to the Soviet Union regarding Israel's biological and chemical warfare capacities.
https://en.wikipedia.org/wiki/Marcus_Klingberg