April 2020. After her arrest for protesting against the government in Syria in 2011, Nouran Alghamian landed in a notorious interrogation center, locked in a bug-infested isolation cell so small that she couldn’t lie down. She begged to see the center’s commander, Anwar Raslan, and pleaded for a normal cell. Mr. Raslan laughed at her, she said, and threw her back into isolation. “He is a criminal and he needs to be tried,” Ms. Alghamian, 28, said by phone from Switzerland, where she has political asylum. On Thursday, she got her wish, when Mr. Raslan and another former Syrian security officer went on trial in Germany on charges of crimes against humanity committed in the early days of Syria’s civil war. Legal campaigners have described the case, in the Higher Regional Court in Koblenz, as a breakthrough for international efforts to hold perpetrators accountable for the extensive abuses committed in the conflict. Most efforts to prosecute Syrian officials in Europe have either been largely symbolic indictments of high-level figures who remain in Syria or trials of low-level soldiers.