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 Israel Lens as discovered there, stated that he died on 18 December 1942 in Camp Annaberg. In it was mentioned an official cause of death as “gangrene and general body weakness” (Gangraen und allgemeine Körperschwäche).
The archives of the Jewish Council of Amsterdam list Israel Lens arriving 3 October 1942 in Camp Westerbork and that he had been deported "eastward" on 5 October 1942.
Private collection of Edward Haduch, Kedzierzyn-Kozle (Poland), the official death certificate of Israel Lens, issued by German authorities (Standesamt) of Annaberg and the Archive of the Jewish Council of Amsterdam.
However, by establishing the date of death of Israel Lens, the official date is maintained as stated after the war by the Dutch Department of Justice.