Research into the wartime civil registries of one of the civil registry offices in Upper Silesias (Poland) discovered many records that corresponded to deaths of inmates from the "Reichsautobahnlager Annaburg" and "Zwangsarbeitslager Niederkirch" camps.
A certificate of death for Mozes de Jong as discovered there, stated that he died on 10 December 1942 in Camp Annaberg. In it was mentioned an official cause of death as “gangrene and myocarditis”. (Gangraen und Herzmuskelentzündung).
The archives of the Jewish Council of Amsterdam list Mozes de Jong being deported from Camp Westerbork "eastward" on 2 October 1942.
Private collection of Edward Haduch, Kedzierzyn-Kozle (Poland), the official death certificate of Mozes de Jong, issued by German authorities (Standesamt) of Annaberg and the Archive of the Jewish Council of Amsterdam.
However, by establishing the date of death of Mozes de Jong, the official date is maintained as stated after the war by the Dutch Department of Justice.