Born in 1903, Heilmann joined the police force in 1925. In May 1939 he joined the SS (SS service number 327324) and at the start of World War II, he was posted to the SS Polizei Division and served during the occupation of France and the Low Countries. In June 1943, he was promoted to Standartenführer and appointed Chief of Staff to the IV SS Panzer Corps whose entire staff was transferred to the VI SS Army Corps.