On 27 September 1939, the security and police agencies of Nazi Germany—with the exception of the Order Police—were consolidated into the Reich Main Security Office (RSHA), headed by Heydrich.[29] The Gestapo became Amt IV (Department IV) of RSHA and Müller became the Gestapo Chief, with Heydrich as his immediate superior.[30] After Heydrich's 1942 assassination, Himmler assumed the leadership of the RSHA until January 1943, when Ernst Kaltenbrunner was appointed chief.[31] Müller remained the Gestapo Chief.