Certain administrative duties in the concentration camps were given by the SS to "prisoner functionaries". Originally, these tasks were assigned to criminal prisoners, but after 1939, political prisoners began to displace the criminal prisoners, though criminals were preferred by the SS. Political prisoners took over important positions as "prisoner functionaries" until liberation. The criminal functionaries were known for their brutality, which they used in order to impress the SS guards and improve their own lot. They were hated by other prisoners, who were eventually able to bring them down by uncovering evidence of theft from camp warehouses.