Johann Breyer, the 89-year-old suspected former Nazi guard arrested last month at his home in Philadelphia, has been denied bail by the U.S. judge overseeing his case, the Associated Press reports. Breyer, who is accused of serving as a guard at Auschwitz and Buchenwald, has been charged with 158 counts of accessory to murder—”one for each trainload of victims brought to Auschwitz during his time there.”

German authorities are attempting to have Breyer extradited to Germany to face trial, and today’s decision means Breyer will remain in a federal prison in Philadelphia until his Aug. 21 extradition hearing. If extradition is approved, his lawyers will likely try and get it blocked on humanitarian grounds—according to the defense, Breyer has heart disease and dementia, and recently had a stroke.

Breyer’s arrest was the culmination of Germany’s recently renewed efforts to identify and arrest former Nazi guards, most of whom are now in their seventies and eighties. Most of them also still live in Germany. Breyer’s case is particularly shocking, since he’s been living in the U.S. since 1952, and hardly in hiding—authorities first tried, unsuccessfully, to extradite him in 1992.