Central to the role Schwarz played as commandant was the provision of slave-laborers to the nearby Buna Werke, a synthetic rubber factory owned by the German chemical company IG Farben. Other German corporations, such as Siemens and Krupp, also received slave labor from Monowitz. The brutal working conditions which prevailed at Monowitz during the period Schwarz served as commandant resulted in a large number of deaths among the inmate population, with estimates ranging between 10,000 and 35,000 prisoners who were believed to have died in the labor camp itself or in the gas chambers located at neighboring Auschwitz-Birkenau.