"As Gestapo chief of operations and later (after 1939) its chief, Müller played a leading role in the detection and suppression of all forms of resistance to the Nazi regime.[12] Under his leadership, the Gestapo succeeded in infiltrating and to a large extent destroying the underground networks of the Communist Party and the Social Democratic Party by the end of 1935."
"As Gestapo chief of operations and later (after 1939) its chief, Müller played a leading role in the detection and suppression of all forms of resistance to the Nazi regime.[12] Under his leadership, the Gestapo succeeded in infiltrating and to a large extent destroying the underground networks of the Communist Party and the Social Democratic Party by the end of 1935."
http://en.wikipedia.org/wiki/Heinrich_M%C3%BCller_%28Gestapo...