The National Archives holds documents showing investigations into allegations that Strehlow was a German sympathiser. The file, held under the 'TE' series (Trading with the Enemy cases) considers specific investigations arising out of suspicions relating to Trading with the Enemy Acts. See National Archives, series number A3201, contents dates 1 Sep 1914 - 31 Jan 1921.
Another interesting file is the 'Investigation case files, single number series with 'SA'. This series comprises a range of sensitive case files covering issues mainly to do with national security. From World War 1, the files were compiled by the Commonwealth Police Force, the South Australian Investigation Branch and the Commonwealth Investigation Service. The files contain, inter alia, translations and original correspondence, records of interrogation and appeal hearings, information garnished from informers and surveillance, aliens, enemy sympathisers, subversive elements, Revolutionaries, Bolshevists, Fascists, enemy espionage, European Fascist parties, Anti-Semitism, reports on internment and internees from both World Wars, cults, sects, Irish National Association activities, propaganda, information on deportations, applications for naturalisation and requests for information from the Immigration authorities. The series also contains confiscated material in the form of photographs, postcards, maps, posters etc. There was a good deal of additions to files from previous series onto this one. National Archives, series number D1915, contents dates 1 Jan 1910 - 31 Dec 1987.
