Joseph Menglele the "Angel of Death", reserved a special barracks for his twin subjects, as well as for dwarfs, cripples and other "exotic specimens." The barracks was nicknamed the Zoo, Mengele's holding pen. Several twins were castrated or sterilized. Many twins had limbs and organs removed in macabre surgical procedures that Mengele performed without using an anesthetic. Other twins were injected with infectious agents to see how long it would take for them to succumb to various diseases.