The Mauthausen camp authorities killed specially targeted groups of persons sent to Mauthausen for that purpose. They also killed those inmates deemed too weak or sick to work.
Several methods of killing were used. As in other camps, the Mauthausen authorities began to use gas as a means of killing in 1941–42. Like some other concentration camps, Mauthausen was equipped with a stationary gas chamber with the capacity to kill up to 80 people at a time by means of Zyklon B gas (prussic acid). In 1942, the Reich Security Main Office provided the camp authorities with a mobile gas van with the capacity to kill about 30 persons at a time. The SS dispatched, in addition, 2,960 prisoners from Mauthausen and 1,881 from Gusen, a total of 4.841 prisoners, to the Hartheim sanatorium and “euthanasia” killing center to be killed. German physicians and camp authorities had selected the victims within the framework of “Operation 14f13,” the extension of the Nazi “euthanasia policy” to the concentration camps.
German doctors subjected Mauthausen prisoners to pseudoscientific medical experiments, including testing levels of testosterone, experimenting with delousing chemicals, medicines for tuberculosis, and nutrition experiments. Camp physician Hermann Richter surgically removed significant organs—e.g., stomach, liver, or kidneys—from living prisoners solely in order to determine how long a prisoner could survive without the organ in question. Eduard Krebsbach, the executive camp doctor between autumn 1941 and autumn 1943, killed an undetermined number of prisoners by injecting phenol directly into their hearts.
The SS also killed thousands of prisoners by shooting, hanging, and mistreatment. Tens of thousands more died as a direct result of the harsh living conditions in the camp, succumbing to starvation, exposure, and disease.