Support WBURSyrians Have Stared Down Threats To Testify Against Assad's Regime In A Landmark TrialPlay08:19Download AudioDeborah AmosSeptember 28, 2021 ShareHassan Mahmoud, 53, is one of the Syrians who testified in a landmark trial in Germany in which a former Syrian security official is charged with crimes against humanity and other crimes for overseeing torture at a prison. (Eman Helal for NPR)