Josias Kumpf left Austria in 1956 to settle in the US
A former SS man alleged to have taken part in the extermination of 8,000 Jews in one day has been freed by Austria, a day after being extradited from the US.
The Austrian justice ministry said the former guard, 83-year-old Josias Kumpf, could not be put on trial because the statute of limitations had expired.
The US says he acted in the killing and burial in pits of Jewish interns at the Trawniki camp in Nazi-occupied Poland.
He left Austria in 1956 to settle in the US, and became a citizen in 1964.
The US justice department sued to strip Mr Kumpf, who lived in Wisconsin, of his citizenship in 2003.
Austrian justice ministry spokeswoman Katharina Swoboda said Vienna had warned the US that Mr Kumpf would not be prosecuted in Austria because the statute of limitations relating to his crimes had expired in 1965.
"We have always pointed out to the United States that he cannot be charged here with the crimes of which he is accused," she said.
'Orders to shoot'
The justice ministry also said Mr Kumpf had been a teenager at the time of the alleged offences and had never been an Austrian citizen.
The opposition Greens have called on the government to amend the law to allow for the prosecution of alleged Nazi war criminals regardless of the time elapsed.
The US justice department said on Thursday that Mr Kumpf had admitted that he stood guard over a pit where prisoners were being gunned down and "finished off" the wounded.
Mr Kumpf was found to have served as a guard at Sachsenhausen concentration camp in Germany and Trawniki in Nazi-occupied Poland, where the mass shooting took place in 1943.
His assignment had been to watch for victims who were still "halfway alive" or "convulsing" and prevent their escape, the US justice department said.
There was no immediate comment from Mr Kumpf or his lawyer, Peter Rogers. They have in the past denied that Mr Kumpf had a role in any atrocities.