While Clauberg and Schumann were busy with experiments designed to develop methods for the biological destruction of people regarded by the Nazis as undesirable, another medical criminal, SS-Hauptsturmführer Josef Mengele, M.D., Ph.D., was researching the issues of twins and the physiology and pathology of dwarfism in close cooperation with the Kaiser Wilhelm Institute of Anthropology, Genetics, and Eugenics in Berlin-Dahlem. He was also interested in people with different colored irises (heterochromia iridii), and in the etiology and treatment of the gangrenous disease of the face known as noma Faciei (cancrum oris, gangrenous stomatitis), a little understood disease endemic to the Gypsy prisoners in Auschwitz.
In the first phase of the experiments, pairs of twins and persons with inherited anomalies were put at the disposal of Dr. Mengele and subjected to all imaginable specialist medical examinations. They were also photographed, plaster casts were made of their jaws and teeth, and they were toe- and fingerprinted. As soon as these examinations were finished, they were killed with lethal injections of phenol to the heart so that the next phase of the experimentation could begin: autopsies and the comparative analysis of their internal organs.