在独ソ連軍政府
In early February 1946, Horst was arrested by the Soviet Military Administration in Germany. After his release he became a member of the SED. From April 1946 to January 1947 he was executive secretary of the Political Department, and staff for the departments of Agriculture and Food of the SED District Board of West Saxony. Then he was secretary of the Personnel Policy Division of the SED district board of Leipzig.