WASHINGTON — In what could prove to be the last Nazi case on American soil, federal officials on Tuesday arrested an 89-year-old immigrant in Philadelphia who is accused of having been a Nazi SS guard at Auschwitz and Buchenwald during World War II.

Johann Breyer, a retired tool maker born in Czechoslovakia, is the oldest person ever accused of ties to the Third Reich by United States authorities who for decades have hunted for Nazis who escaped to America after the war. Mr. Breyer is accused of joining the Waffen SS at age 17 and working as a guard at the concentration camps at Auschwitz and Buchenwald.

Mr. Breyer is accused of working as an armed guard at Auschwitz and taking part in the murders of “hundreds of thousands” of Jews from Hungary, Czechoslovakia and Germany in 1944. Officials said he had worked at the part of the camp known as “Auschwitz 2,” or Birkenau, a section that was particularly notorious. While the Nazis used other parts of Auschwitz for slave labor, the Birkenau section was used exclusively to kill victims in gas chambers.

Mr. Breyer, who immigrated to the United States in 1952, was arrested at his home in Philadelphia, and on Wednesday he was in Federal District Court there to face charges. Germany is seeking to have him extradited to stand trial under a sealed German indictment made public on Wednesday. Germany is charging him with 158 counts of aiding and abetting Nazi atrocities.

Mr. Breyer was held in detention Tuesday night, and was led into the courtroom late Wednesday morning wearing a purple jail uniform with his hands shackled. Appearing pale and thin, he was stooped over and walked with difficulty with a cane. He looked around frequently and waved to his wife, Shirley, who was also in the courtroom.

He seemed puzzled at times, and his lawyer told Magistrate Judge Timothy R. Rice that he suffered from a number of health issues, including mild dementia.

When the judge asked him if he understood that Germany was seeking to extradite him, Mr. Breyer answered: “Yes.” He also said, responding to another question from the judge, that he understood that the man with him at the defense table was his lawyer.

As the case moves forward, there will no doubt be further legal debate over Mr. Breyer’s mental and physical condition, but Judge Rice said that for now he was satisfied. “It seems that Mr. Breyer does have the ability to understand the nature of the proceedings against him,” the judge said.

Because of what he called “the serious nature of the crime,” the judge refused to free Mr. Breyer on bail.

His arrest revives a case that has been dormant for years. The Justice Department first accused Mr. Breyer of Nazi ties and tried to deport him in 1992, but he was ultimately allowed to stay in the country after a legal fight that hinged on his claims that he was born a United States citizen. (His mother was born in the United States.)

While he acknowledged being at Auschwitz for a time, he insisted his service there was “involuntary.”

In the current case, the authorities are using a different legal route against Mr. Breyer, with the Germans seeking to have him extradited to stand trial there. After years of inactivity over people accused of having worked with the Nazis, the Germans in the last several years have mounted a renewed push to charge men who are now in their 80s.

Mr. Breyer’s arrest will most likely reignite a debate in the United States over prosecuting elderly defendants for crimes they are accused of committing decades ago.

In past cases, opponents of the aggressive Nazi-hunting efforts have maintained that the time has passed for prosecuting World War II war crimes. But advocates for an aggressive stance insist that crimes as heinous as those of the Nazis demand justice, no matter how old the defendant.

nytimes.com