Miklós Nyiszli

Miklós Nyiszli (17 June 1901 – 5 May 1956) was a Hungarian prisoner of Jewish heritage at Auschwitz concentration camp. Nyiszli, his wife, and young daughter, were transported to Auschwitz in June 1944. Upon his arrival, Nyiszli volunteered as a doctor and was sent to work at No. 12 barracks where he operated on and tried to help the ill with only the most basic medical supplies and tools. He was under the supervision of Josef Mengele, a Schutzstaffel officer and physician. Mengele decided after observing Nyiszli's skills to move him to a specially built autopsy and operating theatre. The room had been built inside Crematorium II, and Nyiszli, along with members of the 12th Sonderkommando, was housed there.

During Nyiszli's period in the camp, he witnessed many atrocities to which he refers in his book, Dr. ​Mengele boncolóorvosa voltam az auschwitzi krematóriumban (in English: Auschwitz: A Doctor’s Eyewitness Account). Historian Gideon Greif characterized Nyiszli's writings 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.

Source: Miklós Nyiszli on Wikipedia