Wrapping up their almost two year investigation into a man Swiss media have dubbed the "Angel of Death", officials in the central Swiss city of Lucerne said on Wednesday the unidentified suspect had confessed to several of the killings at five separate homes.
The nurse, 34, told investigators he had put his victims - mostly women between the ages of 66 and 95 - out of their misery by injecting them with drug overdoses or smothering them with plastic bags and towels.
"The accused gave as his motive acting out of sympathy, compassion, empathy and salvation on the one hand and also cited total overload and relief for himself and the (nursing) team on the other hand," a statement said.
The report came the same week as Britain's worst mass murderer, a doctor who killed at least 215 of his patients, hung himself in his prison cell, leaving his motive for the killings a mystery that may never be solved.
The report came the same week
as the UK's 'Dr Death' hung himself
A psychiatric review found the Swiss nurse completely competent to stand trial, which was expected to take place late this year or early in 2005.
The case has shocked the country, despite its relatively lenient attitude to euthanasia.
Nine suspicious deaths first came to light at the end of May 2001, after a rash of people died in a special unit for the senile in a home for the elderly in Lucerne, where the man had worked since December 2000.
The suspect, whom authorities have described as well-educated, was arrested after the home's authorities alerted police. He remains in custody.
"The accused gave as his motive acting out of sympathy, compassion, empathy and salvation on the one hand and also cited total overload and relief for himself and the (nursing) team on the other hand"
Investigators widened their probe to include other homes and hospitals where the man had worked, poring over every death. Five bodies were exhumed as part of the investigation.
Euthanasia is tolerated in a number of Swiss cantons, provided strict rules are followed.
Active euthanasia is outlawed in Switzerland, but the country does not regard it as a crime if a doctor assists in suicides by
prescribing lethal drugs that patients close to a painful death take themselves to end their suffering.