German chemist and entrepreneur Bruno Emil Tesch (1890-1946), in 1945

Together with Gerhard Peters and Walter Heerdt, Tesch developed a process for manufacturing hydrogen cyanide so it could be used in a solid form as an insecticide: Zyklon B. Tesch was the owner of Tesch & Stabenow (called Testa), a pest control company he co-founded in 1924 with Paul Stabenow in Hamburg, Germany. Tesch became a supporting member of the Nazi party in 1933. During World War II, Tesch & Stabenow sold massive quantities of Zyklon B to the SS. The gas was sold to concentration camps in Auschwitz, Sachsenhausen, Neuengamme, Gross-Rosen, Majdanek, and Ravensbrück. In these camps, the SS used Zyklon B to murder approximately 1.1 million people. Following the end of World War II, Tesch was arrested by the British as a war criminal, tried, and executed. Tesch and his co-executive, Karl Weinbacher, were the only businessmen to be executed for their role in Nazi atrocities in Western Europe. (Photograph by the United Kingdom Government. Public domain.)