[4] Historian Gideon Greif characterized Nyiszli's assertion that "soap and towels were handed out to the victims" as they entered the gas chambers and that "toxic gas was released from the showerheads" as among the “myths and other wrong and defamatory accounts” of the Sonderkommando that flourished in the absence of first-hand testimony by surviving Sonderkommando members.
[5] While imprisoned, Josef Mengele forced him to engage in human experimentation, including dissecting the bodies of recently executed inmates, due to his scientific background.
[3] At one point Nyiszli was forced to carry out physical exams on a father-son pair and, after their deaths, to prepare their skeletons for study at the Anthropological Museum in Berlin.
As he said: An event never before experienced in the history of medicine worldwide is realized here: Twins die at the same time, and there is the possibility of subjecting their corpses to an autopsy.
"[7]During his roughly eight months in Auschwitz, Nyiszli observed the murders of tens of thousands of people, including the slaughter of whole sub-camps at once.
On 18 January, Nyiszli, along with an estimated 66,000 other prisoners, was forced on a death march through various Nazi territories and further into various smaller concentration camps in Germany.
[3] Nyiszli narrated his testimony of camp life in an objective tone, favoring an analytical approach over a more emotive description.
[1] Nyiszli's first major stop after the forced march out of Auschwitz was the Mauthausen concentration camp in northern Austria, near the city of Linz.
After a three-day stay in a quarantine barracks at Mauthausen, he spent two months in the Melk an der Donau concentration camp, about three hours away by train.