Soon after the outbreak of World War II, the murder of persons regarded as "unproductive" began. Physicians, nurses, and other health professionals participated in the killing of 5,000 disabled or ill children and newborns and the murders of over 70,000 institutionalized psychiatric patients in gas chambers of specially equipped "euthanasia" centers.
After growing public unrest and protests influenced Hitler to halt the gassing program in August 1941, an additional 130,000 people were killed in hospitals and psychiatric wards by means of medical overdoses and starvation.
Scientists used the opportunities to conduct research presented by the "euthanasia" murders and by the imprisonment in concentration camps of Jews, Roma and Sinti, and Polish and Soviet nationals.
Nazi racial hygiene culminated in the near-annihilation of European Jewry, claiming six million lives.