Willem Kaas was the son of Izaak Kaas and Judith Content. He was married to Judith Wurms. The couple lived at 259 Vrolikstraat in Amsterdam. On 16 March 1943 Willem Kaas died in Vught concentration camp.
Records concentration camp Vught, Sterbebuch 1943
In addition, a Jokos file (number 3066) on this family is at the Amsterdam Municipal Archive. Access is subject to authorization from the Stichting Joods Maatschappelijk Werk.