Irmfried Eberl was an Austrian psychiatrist and medical director of the euthanasia institutes in Brandenburg and Bernburg, who helped set up and was the first commandant of the Treblinka extermination camp where he worked as SS-Obersturmführer from 11 July 1942 until his dismissal on 26 August 1942. He was arrested after the end of the war in January 1948. Eberl hanged himself the following month to avoid trial.

Aktion T4 was a campaign of mass murder by involuntary euthanasia in Nazi Germany. The term was first used in post-war trials against doctors who had been involved in the killings. The name T4 is an abbreviation of Tiergartenstraße 4, a street address of the Chancellery department set up in early 1940, in the Berlin borough of Tiergarten, which recruited and paid personnel associated with Aktion T4. Certain German physicians were authorised to select patients "deemed incurably sick, after most critical medical examination" and then administer to them a "mercy death". In October 1939, Adolf Hitler signed a "euthanasia note", backdated to 1 September 1939, which authorised his physician Karl Brandt and Reichsleiter Philipp Bouhler to begin the killing.