Wilhelm Katz and Ida Hess committed suicide because they thought both of their children had died in concentration camps. They are buried in Amsterdam.
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In addition, a Jokos file (number 1888) on this family is at the Amsterdam Municipal Archive. Access is subject to authorization from the Stichting Joods Maatschappelijk Werk.The Jokos file reveals that a claim was lodged for compensation for valuables surrendered to the Lippmann-Rosenthal looting bank (L-claim, number 6232/2234).