jewelry was removed, along with dental work and teeth containing precious metals. Gold was removed from the teeth of dead prisoners from 23 September 1940 onwards by order of Heinrich Himmler. The work was carried out by members of the Sonderkommando who were dentists; anyone overlooking dental work might themselves be cremated alive. The gold was sent to the SS Health Service and used by dentists to treat the SS and their families; 50 kg had been collected by 8 October 1942. By early 1944, 10–12 kg of gold were being extracted monthly from victims' teeth. The corpses were burned in the nearby incinerators, and the ashes were buried, thrown in the Vistula river, or used as fertilizer. Any bits of bone that had not burned properly were ground down in wooden mortars. Death toll At least 1.3 million people were sent to Auschwitz between 1940 and 1945, and at least 1.1 million died. Overall 400,207 prisoners were registered in the camp: 268,657 male and 131,560 female. A study in the late 1980s by Polish historian Franciszek Piper, published by Yad Vashem in 1991, used timetables of train arrivals combined with deportation records to calculate that, of the 1.3 million sent to the camp, 1,082,000 had died there, a figure (rounded up to 1.1 million) that Piper regarded as a minimum. That figure came to be widely accepted. The Germans tried to conceal how many they had murdered. In July 1942, according to Rudolf Höss's post-war memoir, Höss received an order from Heinrich Himmler, via Adolf Eichmann's office and SS commander Paul Blobel, that "[a]ll mass graves were to be opened and the corpses burned. In addition the ashes were to be disposed of in such a way that it would be impossible at some future time to calculate the number of corpses burned." Earlier estimates of the death toll were higher than Piper's. Following the camp's liberation, the Soviet government issued a statement, on 8 May 1945, that four million people had been murdered on the site, a figure based on the capacity of the crematoria. Höss told prosecutors at Nuremberg that at least 2,500,000 people had been gassed there, and that another 500,000 had died of starvation and disease. He testified that the figure of over two million had come from Eichmann. In his memoirs, written in custody, Höss wrote that Eichmann had given the figure of 2.5