Miklós Nyiszli was born on June 17, 1901, in Szilágysomlyó, Transylvania, which was then part of the Austro-Hungarian empire.
He studied medicine, first at the University of Cluj in 1920, then at the University of Kiel in Germany between 1921 and 1924.
Nyiszli then enrolled at the medical faculty of the Silesian Friedrich Wilhelm University in Breslau, Germany, and completed his degree in 1929.
He specialized in forensic pathology and wrote his doctoral dissertation on the indications of causes of death in suicides.
Nyiszli worked under the supervision of Karl Reuter and Georg Strassmann, prominent figures in the field of forensic medicine.
After completing his studies, he returned to Transylvania and established himself as a forensic pathologist, often assisting the police and courts in identifying unusual or disputed causes of death.
In 1937, Nyiszli moved to Maramures, northern Transylvania, and opened a private practice in the small town of Viseul de Sus.
Following the Vienna Award of 1940, Northern Transylvania was returned to Hungary, and Nyiszli was sent to a work camp in the village of Desze.
In May 1944, Nyiszli and his family were deported to Germany, where he worked on the construction site of an artificial rubber factory and later at Auschwitz-Birkenau.
Nyiszli became a Jewish inmate doctor and forensic pathologist, working particularly for Dr. Josef Mengele in the crematorium II of Auschwitz-Birkenau.
He remained at Auschwitz until January 1945, when he was transferred to other concentration camps, including Mauthausen, Melk, and Ebensee.
After the war, Nyiszli returned to Transylvania and offered his deposition before the Budapest Commission for the Welfare of Deported Hungarian Jews.
He published his memoirs in 1946, which became an important document for historical research on Auschwitz and the 'Sonderkommandos'.
Nyiszli also traveled to the Nuremberg Trials and offered his deposition in 1947.
In 1948, he could no longer practice as a private doctor, and he spent the remainder of his life in Oradea, Romania.
Nyiszli's daughter, Susanna, married in 1952 and had a daughter, Monica.
Miklós Nyiszli died of a heart attack on May 5, 1956, in Oradea, Romania.
