A few weeks before the start of World War II, the Nazi government moved from compulsory sterilization to killing of the ill and disabled. From August 1939 on, disabled toddlers were transferred from home care to so-called children's wards and killed there by starvation or poison. This was followed after January 1940 by the mass murder of institutionalized handicapped patients, regardless of age, distributed by region and time among six state psychiatric hospitals and nursing homes (Brandenburg, Bernburg, Grafeneck, Hadamar, Sonnenstein/Pirna and Hartheim/Linz).

In the psychiatric hospital in Bernburg in October 1940, workmen installed a gas chamber disguised as a shower room, an autopsy room, a mortuary, and a crematorium. Patients from hospitals near and far were transferred by bus groups to Bernburg, with the first patients arriving on November 21, 1940. After arrival, they were undressed, registered, photographed, and brought before a physician, who then selected suitablefraudulent causes of death from a list of diagnoses organized by age and state of health. Nurses and aides accompanied each group of 60 to 75 patients to the basement gas chamber, where the patients were asphyxiated by carbon monoxide gas. Up to 1,400 people per month were killed in this way at Bernburg.

The family of each victim received a form letter of "condolence" as well as a death certificate, postdated two or three weeks after the actual date of death. Health insurance companies had to keep paying the daily costs of care for the fictional interim period, even though the person concerned was already dead. Despite these attempts at concealment, the killings did not remain secret. Public unrest in localities near the central "euthanasia" institutions and the public protest sermon delivered on August 3, 1941 by Clemens August, Count von Galen (1878-1946), Roman Catholic bishop of Münster, led the Nazi regime to halt the "euthanasia" gassings on August 24, 1941. Up to this date, more than 9,000 people had been killed in Bernburg alone, with a total of about 70,000 patients murdered in the six "euthanasia" institutions. However, the killings continued until 1945 in a second, "decentralized" phase resulting in the murder of about 200,000 persons by starvation and lethal drug overdoses in about 100 institutions.

Most of the male personnel of the main "euthanasia" institutions were transferred to the Generalgouvernement [General Government] in Poland, where they contributed to the creation and operation of the killing centers at Belzec, Sobibor, and Treblinka.

After the gassings ended, three of the six "euthanasia" killing centers with gas chambers, including Bernburg, remained places of murder for concentration camp prisoners who were unable to work or who were being persecuted for racial reasons under the code name "Operation 14 f 13." The "Operation T4" physicians, who had first selected patients from the state hospitals and nursing homes, were now assigned to select prisoners from the concentration camps. Approximately 5,000 prisoners from the Buchenwald, Gross-Rosen, Flossenbürg, Neuengamme, Ravensbrück, and Sachsenhausen concentration camps, of whom the overwhelming majority were Jewish men and women, died at Bernburg. The Bernburg killing facility was finally closed in the spring of 1943. Its technical facilities, which were preserved, are the core of the memorial today.