An 89-year-old man was arrested at his house in North Philadelphia this week on charges of aiding and abetting Nazi atrocities while working as a guard at the Auschwitz and Buchenwald concentration camps during World War II.

The investigation on Johann "Hans" Breyer has been ongoing for years. Born in Czechoslovakia but an American resident since 1952, the U.S. Justice Department had tried for years to strip Breyer of his citizenship and to deport him, to no avail.

The German government launched its own investigation into his alleged war crimes in 2012. From the Associated Press in September 2012:

The special German office that investigates Nazi war crimes has recommended that prosecutors charge him with accessory to murder and extradite him to Germany for trial on suspicion of involvement in the killing of at least 344,000 Jews at the Auschwitz-Birkenau death camp in occupied Poland.

When Breyer appeared in court this afternoon, his health reportedly seemed waning. From the New York Times:

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.

In the event of Breyer's extradition to Germany, he will be charged with 158 counts of aiding and abetting Nazi atrocities. For his part, Breyer has insisted that his time at Auschwitz was involuntary.

[Image via AP]