Who is Josef Mengele

Josef Mengel is also known as Angel of Death was a Nazi doctor at Auschwitz extermination camp who selected prisoners for execution in gas chambers and led medical experiments on inmates and was also an assistant to a well-known researcher who studied twins at the Institute for Heredity Biology and Racial Hygiene in Frankfurt, Josef started working at Auschwitz. There he had an unlimited supply of twins to study, and he wouldn't get in trouble if they died, he also conducted eye experiments and included attempts to change the eye color by injecting some chemicals into the eyes of a living subjects, consequently, he killed people with heterochromatic eyes so that the eyes could be removed and sent to Berlin for study.