In 1939, with Hitler’s financial backing, a series of “euthanasia centers” began to appear.
Beginning in the fall of 1939, gassing installations were established at Bernburg, Brandenburg, Grafeneck, Hadamar, Hartheim, and Sonnenstein. Patients were selected by doctors and transferred from clinics to one of these centralized gassing installations and killed.
These “euthanasia centers” were widespread throughout Germany.
On January 9, [1939] the first “gassing test” using carbon monoxide took place in the Brandenburg sanitarium. Between 18 and 20 people were killed, watched by psychiatrists, physicians, and nurses. In 1941, the psychiatric institution at Hadamar celebrated the cremation of its 10,000th patient where everyone—secretaries, nurses, and psychiatrists—received a bottle of beer for the occasion.
It was at these centers that the prototype for the mass killings was developed. The “patients” were gassed, and bodies cremated.
| T4 Center | Operation timetable | Number of victims |
| T4 Center | From | Total |
| Grafeneck | 20 January 1940 | 9,839 |
| Brandenburg | 8 February 1940 | 9,772 |
| Bernburg | 21 November 1940 | 8,601 |
| Hartheim | 6 May 1940 | 18,269 |
| Sonnenstein | June 1940 | 13,720 |
| Hadamar | January 1941 | 10,072 |
| Total | 70,273 |
It is important to note that this was almost three years before the first mass killing facility, Chemlo, went into operation. When Chemlo went into operation, the killing became an industry.