In 1940 and 1941, the facility was used by the Nazis to exterminate around 15,000 people in a process that was labelled as euthanasia. The majority of victims were suffering from psychological disorders and intellectual disability, but their number also included inmates from the concentration camps. The institute was set up after the beginning of the Second World War as part of a Reich-wide, centrally coordinated and largely secret programme called Action T4 for the "Elimination of life unworthy of life" (Vernichtung lebensunwerten Lebens) or the killing of what the Nazis called "dead weight existences" (Ballastexistenzen).