[citation needed] In January 1940, Schumann became head of the Grafeneck euthanasia centre in Württemberg, where mentally ill people were gassed with carbon monoxide in the first gas chamber.

Schumann also belonged to a commission of doctors called "Action 14f13", who transferred weak and sick prisoners from Auschwitz, Buchenwald, Dachau, Flossenbürg, Gross-Rosen, Mauthausen, Neuengamme and Niederhangen concentration camps to the euthanasia killing centers.

Here men and women were forcibly sterilized by being positioned repeatedly for several minutes between two X-ray machines, the rays aiming at their sexual organs.

[citation needed] The parts of the body that were treated with the rays experienced severe radiation burns and suppuration (i.e. discharge of pus).

[1] Part of Schumann's control tests, to check whether the radiation had worked, was the so-called semen check: a stick covered with a rubber hose was inserted into the rectum of the victim and the glands stimulated until ejaculation occurred so that the ejaculate could be tested for sperm..."[2] Both kinds of samples were sent to the University of Breslau (today Wrocław) for examination.

Schumann left Auschwitz in September 1944 and was appointed to the Sonnenstein Clinic in Saxony which had earlier been converted into a military hospital.

An application for a license for a hunting gun led to his identity being exposed in 1951, so the German Democratic Republic issued an arrest warrant.

As Robert Jay Lifton has observed "...Schumann has great importance for us because of what he did – intense involvement in both direct medical killing and unusually brutal Auschwitz experiments – and what he was – an ordinary, but highly Nazified man and doctor..."[6]