Sicherheitsdienst , full title
Sicherheitsdienst des Reichsführers-SS , or
SD, was the
intelligence agency of the
SS and the
Nazi Party in
Nazi Germany. The organization was the first Nazi Party intelligence organization to be established and was considered a
sister organization with the
Gestapo, which the SS had infiltrated heavily after 1934. Between 1933 and 1939, the SD was administered as an independent SS office, after which it was transferred to the authority of the
Reich Main Security Office (
Reichssicherheitshauptamt; RSHA), as one of its seven departments/offices. Its first director,
Reinhard Heydrich, intended for the SD to bring every single individual within the Third Reich's reach under "continuous supervision."