 From the age of seven , Stockhausen lived in Altenberg , where he received his first piano lessons from the Protestant organist of the Altenberg Cathedral , Franz @-@ Josef Kloth ( Kurtz 1992 , 14 ) . In 1938 his father remarried . His new wife , Luzia , had been the family 's housekeeper . The couple had two daughters ( Kurtz 1992 , 18 ) . Because his relationship with his new stepmother was less than happy , in January 1942 Karlheinz became a boarder at the teachers ' training college in Xanten , where he continued his piano training and also studied oboe and violin ( Kurtz 1992 , 18 ) . In 1941 he learned that his mother had died , ostensibly from leukemia , although everyone at the same hospital had supposedly died of the same disease . It was generally understood that she had been a victim of the Nazi policy of killing " useless eaters " ( Stockhausen 1989a , 20 – 21 ; Kurtz 1992 , 19 ) . The official letter to the family falsely claimed she had died 16 June 1941 , but recent research by Lisa Quernes , a student at the Landesmusikgymnasium in Montabaur , has determined that she was gassed along with 89 other people at the Hadamar Euthanasia Centre in Hesse @-@ Nassau on 27 May 1941 ( Anon . 2014 ) . Stockhausen dramatized his mother 's death in hospital by lethal injection , in Act 1 scene 2 ( " Mondeva " ) of the opera Donnerstag aus Licht ( Kurtz 1992 , 213 ) . In the autumn of 1944 , he was conscripted to serve as a stretcher bearer in Bedburg ( Kurtz 1992 , 18 ) . In February 1945 , he met his father for the last time in Altenberg . Simon , who was on leave from the front , told his son , " I 'm not coming back . Look after things " . By the end of the war , his father was regarded as missing in action , and may have been killed in Hungary ( Kurtz 1992 , 19 ) . A comrade later reported to Karlheinz that he saw his father wounded in action ( Maconie 2005 , 19 ) . Fifty @-@ five years after the fact , a journalist writing for the Guardian newspaper stated unequivocally , though without offering any fresh evidence , that Simon Stockhausen was killed in Hungary in 1945 ( O 'Mahony 2001 ) . 
