Van deze persoon is ook een JOKOS-dossier (nummer 60740) aanwezig op het Gemeentearchief van Amsterdam. Voor inzage is toestemming nodig van de stichting Joods Maatschappelijk Werk.
A recently found document indicates that Mauritz de Vries never reached Auschwitz. He died in the train bound for Auschwitz and was probably thrown out of the train. His body was found near the station in Ehrenforst.
The official date of death, specified in his death certificate is 18 November 1942.