During the Khmer Rouge's brutal reign in Cambodia during the mid-to-late 1970s, a former math teacher named Duch served as the commandant of the S-21 security center, where as many as 20,000 victims were interrogated, tortured, and executed. In 2009 Duch stood trial for these crimes against humanity. While the prosecution painted Duch as evil, his defense lawyers claimed he simply followed ordeā¦