Cambodia's genocide tribunal has formally indicted a former prison chief of the country's notorious Khmer Rouge, setting the stage to put him on trial. The UN-assisted tribunal said in a statement Tuesday that its investigating judges issued the indictment upon ending their investigation in the case against Kaing Guek Eav, also known as Duch, who headed the notorious S-21 prison, which was used as a torture center. Duch, charged with crimes against humanity and war crimes, is the first suspect to be indicted by the tribunal. His trial is expected to begin in late September. Four other senior members of the Khmer Rouge, who held power in the late 1970s, are also in custody on similar charges.