DETMOLD, Germany — A 94-year-old former SS sergeant went on trial Thursday in western Germany on 170,000 counts of accessory to murder, based on accusations that he served as a guard in the Auschwitz death camp as hundreds of thousands of Hungarian Jews and others were gassed to death there. Reinhold Hanning seemed in good condition for his age, walking into the court in the city of Detmold without even the help of a cane and appearing to listen attentively as the indictment against him was read aloud. No pleas are entered in the German system.