Patients were murdered or abused as part of the Nazi’s euthanasia programme - also known as Aktion T4.
Historian Herwig Czech, a research fellow at the Documentation Centre of the Austrian Resistance, found that between November 1940 and May 1941 a total of 675 people were taken from the clinic to the euthanasia centre at Hartheim castle near Linz, where they were gassed.
Of these, 116 were children and teenagers between the ages of four and 17.
Action T4 was brought to an end by Hitler’s order in 1941 after protests by the Roman Catholic Church. However, the killings continued.
Czech told the Austrian Press Agency that Gugging was the scene “of some of the most barbarous medical crimes committed in Austria”.
One doctor, Emil Gelny, murdered some 400 people using poison and a specially adapted device for administering electric shocks. He killed some of his patients in front of other psychiatrists, to demonstrate how effective his method was.
Rudolf Lonauer, the head of Hartheim, visited Gugging for almost two weeks in 1943 and the number of deaths surged. He was recorded as the attending doctor for 112 deaths. He typically murdered his patients - mainly women - with an overdose of drugs.
Many other patients died as a result of hunger and infectious disease or were deported to institutions where their chances of survival were minimal.
One of these was the Viennese clinic Am Spiegelgrund, where a (still unknown) number of children from Gugging were murdered. One estimate puts the number of victims at 110.
Czech found that by 1939 the death rate at the hospital had risen by 23 percent and by 1941 by 44 percent. He believes that some 1,420 people had been murdered at Gugging by 1946 - not including those who were transferred to other institutions and died there.
The location of the former hospital is now home to the Institute of Science and Technology Austria, known as IST Austria.
His complete paper, entitled "Nazi Medical Crimes at the Psychiatric Hospital Gugging", is available online as a PDF.