He is accused of killing one of his 25 victims by putting a bucket over his head and hitting it with a heavy plank.
The suspect, identified only as 49-year-old Nikola J, was arrested in Dusseldorf last December. He was the second Bosnian Serb to have been arrested in Germany on charges related to ethnic cleansing during Bosnia's civil war. The first, Dusan Tadic, is on trial at the International War Crimes Tribunal in The Hague.
Nikola J is accused of genocide, murder, kidnapping and extortion, said the Karlsruhe law agency.
In June 1992, he and another Bosnian Serb soldier shot at a group of Muslims in Grapska, killing 22 people, including three women and a child, the prosecutor's office said.
Also that month, a Bosnian Serb unit led by him rounded up Muslims in Sevarilje. He called two people out of the group and ordered a member of his unit to shoot one.
"The soldier did this," the agency said. "After that, many shots were fired, either by the suspect himself or by the soldier he gave orders to, killing the second victim as well."