the holocaust Endlösung der jüdischen Frage or "Final Solution of the Jewish Question") was planned and ordered by leading Nazis, with 
Heinrich Himmler playing a key role. While no specific order from Hitler authorizing the mass killing has surfaced, there is documentation showing that he approved the 
Einsatzgruppen, killing squads that followed the German army through Poland and Russia, and that he was kept well informed about their activities. The evidence also suggests that in the fall of 1941 Himmler and Hitler decided upon mass extermination by gassing. During interrogations by Soviet 
intelligence officers declassified over fifty years later, Hitler's valet 
Heinz Linge and his military aide Otto Gunsche said Hitler had "pored over the first blueprints of 
gas chambers." Also his private secretary, Traudl Junge, testified that Hitler knew all about the death camps.