IIb, led by Hans Hefelmann, which dealt with the Reich government and clemency petitions; Office IIc, overseen by Reinhold Vorberg, responsible for matters related to the armed forces, the police, the SS, and churches; and Office IId for matters concerning the Nazi Party, which was headed by Amtsleiter Buchholz and then by Dr. Brümmel. In January 1940, Brack gave August Becker the task of arranging gas-killing operations of mentally ill patients and other people whom the Nazis deemed "life unworthy of life". The Aktion T4 program was related to popular early 20th-century ideas of eugenics and improving the race, not allowing disabled or mentally ill people to reproduce. Initially, the doctors in the program sterilized people, but then they murdered nearly 15,000 German citizens at Hadamar Euthanasia Centre under an extension of this program. There were six principal killing centers; these resided at Hartheim, Sonnenstein, Grafeneck, Bernburg, Brandenburg, and Hadamar; most of which, historian Robert Lifton points out, "were in isolated areas and had high walls—some had originally been old castles—so that what happened within could not be readily observed from without." Given the scale of the operation, Brack recruited personnel using his network of contacts and party connections to fully staff T4, none of whom were forced to participate but volunteered their services. The T4 killings took place from September 1939 until the end of the war in 1945; from 275,000 to 300,000 people were killed in psychiatric hospitals in Germany and Austria, occupied Poland and the Protectorate of Bohemia and Moravia (now the Czech Republic). Role in the Holocaust During October 1941, Adolf Eichmann and Brack decided to begin using "gas vans" to murder Jews incapable of working, the first three of which were set up at Chełmno extermination camp. Not only did the Einsatzgruppen mobile units assigned there kill Jews, but they also gassed Gypsies, people suffering with typhus, Soviet POWs, and the insane; all of whom were led into the vans, murdered, and then driven to nearby woods so their bodies could be placed in mass graves. On 23 June 1942 Brack wrote the following letter to Himmler: Brack only intended to spare these 2–3 million Jews capable of work provided they were accordingly sterilized. Following these recommendations, Himmler ordered the procedure to be tested on prisoners in Auschwitz. Since Brack was transferred to an SS division, his deputy Blankenburg took over responsibility for the task