After taking his children to stay with relatives in Witzenhausen (in Hesse) to protect them from the expected fall of Berlin to the Russians, Cauer, against advice, returned to Berlin. His body was located after the end of the war in a mass grave of victims of Russian executions. Cauer had been shot dead in Berlin-Marienfelde by Soviet soldiers as a hostage. Soviet intelligence was actively looking for scientists they could use in their own researches and Cauer was on their list of people to find but it would seem that this was unknown to his executioners.
