On June 5, 1942, the Nazis reported having killed 97,000 Jews in specially constructed gas vans. Friedrich August Jeckeln — who served as an SS and police leader in the occupied Soviet Union during World War II — testified in 1945 that Reich Leader Heinrich Himmler, who organized the mass murder of Jews, told him shootings were too impractical, so gas vans were devised as a more efficient system. The method was initially used against the mentally insane in Polish hospitals in 1939. By 1942 the Nazis had begun to deploy more than 36 of these specially designed and equipped vans. In his testimony, survivor Oscar Benedikt tells of his tragic loss in such a van.