He and his boss, Bruno Tesch, were the only businessmen to be executed for their roles in Nazi atrocities and the Holocaust in Western Europe.

Weinbacher worked at Degesch (Deutsche Gesellschaft für Schädlingsbekämpfung, which translates as German Corporation for Pest Control) until 1924, and then at Tesch & Stabenow (Testa, for short), where he received the position of manager in 1927, and by 1943 was director and deputy executive under owner and chief executive officer Bruno Tesch.

Testa manufactured and sold Zyklon B, which was used not only for pest control and disinfestation, but also in the Holocaust in the gas chambers of Auschwitz to murder people.

Weinbacher received a commission on all of the company's profits, including the Zyklon B sales.

After the end of World War II, Weinbacher, Tesch and Joachim Drosihn, the firm's first gassing technician, were arrested on 3 September 1945.