 He joined the Sicherheitsdienst or SD on 29 October 1935 and eventually obtained the rank of Gruppenführer.He was also recalled to service in the Wehrmacht, serving in July 1940 as a member of a machinegun company.From 19 July 1940 until 29 August 1943, he was the commander of the Security Police and SD in the occupation of the Netherlands, where many of his war crimes occurred.