Address: Praha 1, Široká 55/8
Karel Mahler was born on 25 September 1920. His parents were Jindřich Mahler and Klara née Rimer. His sister Sylvia was born in 1912. His father died on 23 December 1932. His last residence before deportation was in Charbuzice, a village in Kralovohradecký kraj. On 21 December 1942 he was deported — together with his mother — with transport Ci from Hradec Králové to Theresienstadt concentration camp. His transport number was 214. On 1 February 1943 mother and son were deported with transport Cu (train 109) to Auschwitz concentration camp. His transport number was 441. Karel Mahler was murdered by the Nazi regime, most probably still in 1943.

His sister Sylvia could survive the Shoah. She was married with Otto Adler. The couple had at least one daughter.