Stangl became a member of the Austrian Nazi Party in 1931 when it was an illegal association for an Austrian police officer at that time. After the war, he denied having been a Nazi since 1931 and claimed that he had enrolled as member of the party only to avoid arrest following the Anschluss of Austria into Nazi Germany in May 1938. Records suggest that Stangl contributed to a Nazi aid fund but he disavowed knowing about the intended party purpose of the fund. Stangl had Nazi Party number 6,370,447 and SS number 296,569.