Recruited from professional police officers, their role and organization was quickly established after Hitler gained power in March 1933 by Hermann Goering. Rudolf Diels was the first head of the organization, initially called Department 1A of the Prussian State Police.
The role of the Gestapo was to investigate and combat "all tendencies dangerous to the State." They had the authority to investigations treason, espionage, and sabotage cases, and cases of criminal attacks on the Party and State.
The Gestapo's actions were not restricted by the law or subject to judicial review. The Nazi jurist, Dr. Werner Best, stated "As long as the [Gestapo]... carries out the will of the leadership, it is acting legally."
The power of the Gestapo most open to misuse was Schutzhaft - the power to imprison people without judicial proceedings on the basis of "protective custody."
During World War II, the Gestapo was expanded to around 45,000 members, it helped control conquered areas of Europe and identify Jews, Socialists and homosexuals for transportation.
At the Nuremberg Trials the entire organization was charged with crimes against humanity.