Historians working on excavating a hidden hospital graveyard in Austria say they have now removed all of the 221 bodies that were buried there.
When they were unearthed last year it was widely reported that all of the bodies were from victims of the Nazi euthanasia project, but historians say that even now, a year-and-a-half later it is still too early to confirm this.
The bodies were discovered during building work on the site in Hall in Tyrol, and the excavation work was halted as a search began to trace the identities of the victims and their families.
Historian Oliver Seifert found documents, during a reorganisation of the hospital archives, showing the death rate of patients at Hall went up considerably towards the end of the war, despite the fact that the institution was not officially part of the Nazis' euthanasia programme, under which tens of thousands of people with disabilities were killed.
The graves may throw light on the way in which euthanasia as a policy was decentralised and, even without orders from on high, became systematic in many psychiatric institutions across the Third Reich whose head doctors bought into the Nazi belief that people with mental disorders were unworthy of life.
"We know that murder was actively carried out at other psychiatric institutions, by overdosing patients, neglect or undernourishment," Seifert said.
Until now there had been no official documentation supporting the idea that patients at Hall, which still operates as a psychiatric institution, had been murdered, although at least 360 patients from Hall are believed to have been taken to other institutions to be killed.
Christian Haring, deputy medical director of the hospital, said authorities were working on the theory that the graveyard was built at a time when Hall was being considered as the site of an official Nazi euthanasia centre.
"It's quite possible that the hospital cemetery was laid out in October 1942 with a view to using Hall for euthanasia," he said, adding that patients died in significant numbers, with 30 deaths registered in March 1945 alone.
Excavation work on the graves started last March after the snow had melted and scientists are still looking at the causes of death. The investigative team includes historians, archaeologists and medical experts.
The hospital said it had managed to identify all of the victims after it launched a global appeal for those who believe their relatives might be among the dead to contact them. It also called for witnesses to come forward with any information that might help.
"Every memory has the potential to help us in researching the history of this cemetery," a spokesman said.
Bertrand Perz who is heading the historical commission investigating the case said that so far they have come across no evidence that the bodies belong to people who were victims of the Nazi euthanasia program – but likewise they have also not yet come across anything that ruled that out.
It is estimated that it will take another year before a final report can be prepared.