The date listed here is incorrect.
Asser appears in the Auschwitz Leichenhalle book, which per Auschwitz museum's website, indicates: "Leichentrager kommando was responsible for taking corpses of dead prisoners or prisoners killed in the camp hospital, prisoners shot against the Death Wall, prisoner…
In addition, a Jokos file (number 52146) on this family is at the Amsterdam Municipal Archive. Access is subject to authorization from the Stichting Joods Maatschappelijk Werk.