The Nazis reorganized Germany's police forces after taking power in 1933, placing them under the control of Heinrich Himmler. Himmler oversaw the SS, ordinary police (Orpo), security police (Sipo), and security service (SD). The SS became an auxiliary police force with powers of arrest. Separately, the Gestapo was the secret state police whose key role was to identify and remove potential threats to Hitler and Germany. Through intimidating tactics like arbitrary arrest and torture, the Gestapo was able to control the population and send thousands to prisons or concentration camps based on public denunciations, achieving control with a small membership through instilling fear.