The exact number of victims at Auschwitz is impossible to fix with certainty. Since the Nazis destroyed a number of records, immediate efforts to count the dead depended on the testimony of witnesses and the defendants on trial at Nuremberg. While under interrogation Rudolf Höss, commandant of Auschwitz concentration camp from 1940 to 1943, said that Adolf Eichmann told him that two and a half million Jews had been killed in gas chambers and about half a million had died "naturally"