PHILADELPHIA (AP) — German efforts to prosecute aging war criminals suffered a setback this week with the death of a retired Philadelphia toolmaker who had long been in the crosshairs of Nazi hunters.

Bavarian prosecutors had hoped to extradite 89-year-old Johann “Hans” Breyer because of his alleged service as a Waffen SS guard at Auschwitz in 1944.

However, Breyer died at a Philadelphia hospital Tuesday, hours before a U.S. judge approved the extradition request. He had spent a month in jail since his arrest on charges of accessory to murder in the deaths of 216,000 Jews.

“It is very unfortunate that Breyer died but this in no way shape or form should discourage the prosecution of Nazi perpetrators who can still be brought to justice,” said Efraim Zuroff, the head Nazi hunter at the Simon Wiesenthal Center in Jerusalem.

Breyer’s death was disclosed Wednesday just as U.S. Magistrate Timothy Rice approved the extradition request, which would still have needed final U.S. government review.

Rice found probable cause that Breyer was the person being sought by German prosecutors in the Bavarian town of Weiden over his suspected service as an SS guard at Auschwitz during World War II.

“No statute of limitations offers a safe haven for murder,” Rice wrote in his 31-page ruling.

“A death camp guard such as Breyer could not have served at Auschwitz during the peak of the Nazi reign of terror in 1944 without knowing that hundreds of thousands of human beings were being brutally slaughtered in gas chambers and then burned on site,” Rice wrote.

Breyer had claimed he was unaware of the massive slaughter at Auschwitz and then that he did not participate in it, but “the German allegations belie his claims,” the judge wrote.

Breyer died at Thomas Jefferson University Hospital, according to his lawyer, Dennis Boyle, and the U.S. Marshals Service. The lawyer said Breyer’s health had deteriorated in jail but he didn’t know the cause of death.

Boyle had argued in bail papers that Breyer was too frail to remain in custody, given his history of heart disease, stroke and dementia.

German authorities in Weiden issued a 2013 warrant charging Breyer with accessory to murder under the theory that the death camp’s sole function was to kill people.

The same legal strategy had been used to charge and convict former Ohio autoworker John Demjanjuk on charges he served as a death camp guard at Sobibor in occupied Poland. Demjanjuk died in a Bavarian nursing home in 2012 while appealing his 2011 conviction.

The 2013 warrant accused Breyer of 158 counts of accessory to murder — one count for each trainload of victims brought to the Auschwitz death camp in occupied Poland from May to October 1944, when he was allegedly a guard there.

Breyer told The Associated Press in a 2012 interview that while he was a guard at Auschwitz, he was assigned to a part of the camp that was not involved in the slaughter of Jews and others.

“I didn’t kill anybody, I didn’t rape anybody — and I don’t even have a traffic ticket here,” he said. “I didn’t do anything wrong.”

Breyer moved to Philadelphia after World War II and for decades lived a quiet, middle-class life with his wife, children and grandchildren. He had American citizenship because his mother was born in the U.S.; she later moved to Europe, where Breyer was born.

In 1992, the U.S. government tried to revoke Breyer’s citizenship after discovering his wartime background. The effort became a decade-long legal saga and appeared to end with a 2003 decision that found that Breyer had joined the SS as a minor and could therefore not be held legally responsible for participating in it.

Then he was arrested last month outside his home in northeast Philadelphia based on the German warrant. Officials say the arrest was delayed for a year because of the complexity of the extradition request.

“This hurts. This hurts the families of the victims. This hurts anyone who is interested in justice,” Zuroff said. “We want to urge everybody involved in this effort, particularly prosecutors, not to let this discourage them from continuing their work.”

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