Josef Mengele was a Nazi officer and physician who performed horrific medical experiments on prisoners at the Auschwitz concentration camp during World War II. He took a particular interest in experimenting on twins, seeking to advance Nazi racial ideology about Aryan genetic superiority. Mengele's experiments caused immense suffering and death for his victims. After the war, he evaded capture and lived in hiding in South America until his death by drowning in 1979 in Brazil.