Josef Mengele (German: [ˈjoːzɛf ˈmɛŋələ] ( listen); 16 March 1911 – 7 February 1979) was a German Schutzstaffel (SS) officer and physician in Auschwitz concentration camp during World War II. Mengele was a notorious member of the team of doctors responsible for the selection of victims to be killed in the gas chambers and for performing deadly human experiments on prisoners. Arrivals deemed able to work were admitted into the camp, and those deemed unfit for labor were immediately killed in the gas chambers. Mengele left Auschwitz on 17 January 1945, shortly before the arrival of the liberating Red Army troops. After the war, he fled to South America, where he evaded capture for the rest of his life. Josef Mengele received doctorates in anthropology and medicine from Munich University and began a career as a researcher. He joined the Nazi Party in 1937 and the SS in 1938. Initially assigned as a battalion medical officer at the start of World War II, he transferred to the concentration camp service in early 1943 and was assigned to Auschwitz. There he saw the opportunity to conduct genetic research on human subjects. His subsequent experiments, focusing primarily on twins, had no regard for the health or safety of the victims.

Assisted by a network of former SS members, Josef Mengele sailed to Argentina in July 1949. He initially lived in and around Buenos Aires, then fled to Paraguay in 1959 and Brazil in 1960 while being sought by West Germany, Israel, and Nazi hunters such as Simon Wiesenthal so that he could be brought to trial. In spite of extradition requests by the West German government and clandestine operations by the Israeli intelligence agency, Mossad, Mengele eluded capture. He drowned while swimming off the Brazilian coast in 1979 and was buried under a false name. His remains were disinterred and positively identified by forensic examination in 1985.