As Gestapo chief, Muller first oversaw the ruthless crushing of any resistance to Nazi rule as Hitler cemented his grip on power in the 1930s, and then, following the invasion of the Soviet Union in 1941 he helped organise the work of the Einsatzgruppen. The Nazi paramilitary death squad was charged with eliminating Bolsheviks and Jews, the groups claimed the lives of an estimated 1.4 million Jews in just 12 months.