Josef Mengele was a German physician and SS officer during World War II, known for his inhumane medical experiments on prisoners at the Auschwitz concentration camp. He was particularly interested in genetics and conducted cruel experiments on twins, often leading to severe suffering or death. After the war, Mengele evaded capture and fled to South America, living in countries like Argentina and Brazil. He remained a fugitive for decades, and despite efforts to locate him, he died in 1979 without facing justice for his actions during the Holocaust.