Question: Am Spiegelgrund was the name of a children's clinic in Vienna where 789 children were killed under the Aktion T4, was a postwar name for mass murder through involuntary euthanasia in which Nazi controlled country?

Context paragraphs:
Gerhard Kretschmar: Gerhard Herbert Kretschmar (20 February 1939 – 25 July 1939), was a German child born with severe disabilities.  After receiving a petition from the child's parents, the German Führer Adolf Hitler authorized one of his personal physicians, Karl Brandt, to have the child killed.  This marked the beginning of the program in Nazi Germany known as a "euthanasia program" (Aktion T4) which ultimately resulted in the deliberate killing of about 200,000 people with mental and/or physical disabilities.

Am Spiegelgrund clinic: Am Spiegelgrund was the name of a children's clinic in Vienna where 789 children were killed under the Nazi Regime Children's Euthanasia Program, also known as Aktion T4.  Between 1940-1945, the clinic operated as part of the psychological institution “Am Steinhof” (renamed the Otto Wagner Clinic) on the Baumgartner Höhe, now located in Penzing, the 14th district of Vienna.  This clinic was divided into a reform school and a sanatorium for children, which included a so-called Children’s Ward, where sick, disabled, and otherwise ‘un-educable’ adolescents were abused and subjected to harsh medical experiments.  Some died by lethal injection and gas poisoning; others by disease, undernourishment, exposure to the elements, and 'accidents' relating to their conditions.  The brains of up to 800 victims were preserved in jars and housed in the hospital for decades.

Ernst Illing: Dr. Ernst Illing (1904 - 1946) was medical director of the Vienna Psychiatric-Neurological Clinic for Children Am Spiegelgrund clinic, where hundreds of children were killed during World War II.  After joining the Nazi party in 1933, Illing held various positions, including senior physician for the Luftwaffe, before becoming director of the Spiegelgrund clinic in 1942.  He was tried and hanged as a war criminal in 1946.

Nazi euthanasia and the Catholic Church: During the Second World War, the Roman Catholic Church protested against Aktion T4, the Nazi involuntary euthanasia programme under which the mentally ill, physically deformed, and incurably sick were to be killed.  The protests formed one of the most significant public acts of Catholic resistance to Nazism undertaken within Germany.  The euthanasia programme began in 1939, and ultimately resulted in the murder of more than 70,000 people who were senile, mentally handicapped, mentally ill, epileptics, cripples, children with Down's Syndrome, or people with similar afflictions.  The murders involved interference in Church welfare institutions, and awareness of the murderous programme became widespread.  Church leaders who opposed it – chiefly the Catholic Bishop August von Galen of Munster and Protestant Bishop Theophil Wurm – were therefore able to rouse widespread public opposition.

Dasein ohne Leben: Dasein ohne Leben – Psychiatrie und Menschlichkeit ("Existence Without Life" – "Psychiatry and Humanity") is a 1942 Nazi propaganda film about the physically and mentally disabled: closeups of disabled persons.  The director was Hermann Schwenninger, one of the three managing directors of Gemeinnützige Krankentransport ("Charitable Ambulance"), a front company of Aktion T4, the central institution for the mass murder of patients in the Third Reich.  Schwenninger also wrote parts of the screenplay of "Ich klage an".  The contract for the film came from Hitler's Chancellery, and was produced by Tobis Film.

Philipp Bouhler: Philipp Bouhler (11 September 1899 – 19 May 1945) was a senior Nazi Party official who was both a "Reichsleiter" (National Leader) and Chief of the Chancellery of the Führer of the NSDAP.  He was also an SS-"Obergruppenführer" in the "Allgemeine SS" who was responsible for the Nazi "Aktion T4" euthanasia program that killed more than 70,000 handicapped adults and children in Nazi Germany, as well as co-initiator of "Aktion 14f13", also called "Sonderbehandlung" ("special treatment"), that killed 15,000–20,000 concentration camp prisoners.

Aktion T4: Aktion T4 (German, ] ) was a postwar name for mass murder through involuntary euthanasia in Nazi Germany.  The name T4 is an abbreviation of "Tiergartenstraße 4", a street address of the Chancellery department set up in the spring of 1940, in the Berlin borough of Tiergarten, which recruited and paid personnel associated with T4.  Certain German physicians were authorized to select patients "deemed incurably sick, after most critical medical examination" and then administer to them a "mercy death" ("Gnadentod") .  In October 1939 Adolf Hitler signed a "euthanasia decree" backdated to 1 September 1939 that authorized his personal physician Karl Brandt and "Reichsleiter" Philipp Bouhler to implement the programme.

Artur Hojan: Artur Hojan (7 August 1973 – found dead, 9 February 2014) was a journalist and published author specializing in the history of the Chełmno extermination camp and the Nazi involuntary euthanasia programme conducted in the territory of occupied Poland by the SS during World War II.  Hojan was the co-founder of the "Tiergartenstrasse4" Association in 2005 (together with Cameron Munro) devoted to Aktion T4 history, with emphasis on the Kościan psychiatric hospital located where he lived.  Hojan, age of 40, left home in the evening of 1 December 2013 at 8 p.m. for a walk around town and disappeared.  His body was found two months later on 9 February 2014 floating in the Obra canal near the town of Kiełczewo, and identified later.  The cause of death has not been determined.  He was buried at the Kościan cemetery on 15 February 2014.  He left behind a wife and young daughter.  The monograph "Treblinka Death Camp: History, Biographies, Remembrance" by Chris Webb, the co-founder of H.E.A.R.T (also known as the HolocaustResearchProject.org), is dedicated to his memory.

Memorandum Authorizing Involuntary Euthanasia: Adolf Hitler signed a memorandum authorizing involuntary euthanasia in October 1939 to serve as the legal basis for Aktion T4, the Nazi forced euthanasia program.  Its purpose was to assure the doctors and nurses who took part in the euthanasia program would not be prosecuted for murder.  During the postwar trials of these same individuals, they attempted to use this decree as a justification for their actions.

Karl Freiherr Michel von Tüßling: Karl Freiherr Michel von Tüßling (27 July 1907 – 30 October 1991) was a Schutzstaffel (SS) officer who served in the Nazi government of German dictator Adolf Hitler and in the SS Main Office.  From 1936 onwards, he was the personal adjutant of "Reichsleiter" and SS-"Obergruppenführer" Philipp Bouhler, who was in charge of Hitler's Chancellery (Kanzlei des Führers), head of the euthanasia programme Aktion T4, as well as co-initiator of Aktion 14f13.  In 1947 Tüßling provided an affidavit in defence of war criminal Viktor Brack who was sentenced to death at the Nuremberg trials.

Supporting paragraphs: Am Spiegelgrund clinic Aktion T4
Answer: Germany