castle near hartheim, austria, at which the Nazis killed people with physical and mental disabilities by gassing and lethal injection in order to purify the German race. Later, thousands of concentration camp prisoners from dachau, Melk, Gusen and Mauthausen were gassed here as well.

The Nazis began experimenting with poison gas for the purpose of mass murder in late 1939 with the killing of mental patients. they called this 'euthnasia'. A Nazi euphemism, 'euthanasia' referred to the systematic killing of those Germans whom the Nazis deemed unworthy of life because of mental illness or physical disability (see transport of invalids). Six gassing installations were established as part of the Euthanasia Program: Bernburg, Brandenburg, Grafeneck, Hadamar, Hartheim, and Sonnenstein. These killing centers used pure, chemically manufactured carbon monoxide gas.these experiments lead to the gas chambers in the concentration camps.