Inaccessible to Western scholars until the USSR's collapse, File -19/9 of the Red Army's intelligence branch came to historian Gerald Fleming's attention in May 1993. It contained information about Kurt Prüfer, Fritz Sander, and other German engineers employed by Topf und Söhne (Topf and Sons), whose products included crematorium furnaces in Nazi camps at Buchenwald, Dachau, Mauthausen, Gross-Rosen, and Auschwitz-Birkenau.

In late 1944 the Germans destroyed equipment and records at Auschwitz-Birkenau, but that death factory was too big to cover up. When the Red Army liberated the camp two months later, the massive evidence contained, in Fleming's words, details about "the construction of the technology of mass death, complete with the precise costs of crematoria and calculations of the number of corpses each could incinerate in a day." Thus, beyond documenting the Red Army's arrest of Prüfer and Sander, File -17/9 contained transcripts of the interrogations that followed.

The construction of Auschwitz-Birkenau's four carefully planned gas chamber-crematorium units took considerable time, largely because of wartime building constraints. Topf was only one of 11 civilian companies needed to produce them. Utilizing prisoner labor, building began in the summer of 1942, but it was nearly a year before the last facility was operational. Each included an undressing room, a gas chamber, and a room containing Topf's incineration ovens. These lethal places were designed to dispatch thousands of Jews per day. Even so, Prüfer told his Red Army interrogators that "the [crematorium] bricks were damaged after six months because the strain on the furnaces was colossal."

"From 1940 to 1944," Prüfer stated, "20 crematoria for concentration camps were built under my direction." His work took him to Auschwitz five times, and he knew that "innocent human beings were being liquidated" there. So did one of Prüfer's superiors, Sander, a crematorium ventilation specialist whose work for Topf took him to Auschwitz three times. Red Army interviews show that Sander submitted plans in late 1942 for a crematorium with even greater capacity. Although never built, it would have used "the conveyor-belt principle," he explained. "That is to say, the corpses must be brought to the incineration furnaces without interruption." His duty, Sander claimed on March 7, 1946, had been to use his "specialist knowledge...to help Germany win the war, just as an aircraft-construction engineer builds airplanes in wartime, which are also connected with the destruction of human beings."

Less than three weeks later, Sander died in Red Army custody, the victim of a heart attack. Sentenced to "25 years deprivation of liberty," Prüfer died of a brain hemorrhage on October 24, 1952.
Photo: Bilderdienst SYddeutscher Verlag