Chief Khmer Rouge interrogator Duch on Tuesday (November 20) made the first public appearance by a senior Pol Pot cadre at the tribunal investigating Cambodia's genocide during the Khmer Rouge regime in the 1970's. Duch, ex-commandant of the notorious S-21 interrogation centre, now 66, listened as prosecutors read out allegations of torture during a televised bail hearing. Duch, also known as Kaing Guek Eav, is appealing against his detention last July when he was charged with crimes against humanity by the joint court set up to prosecute "those most responsible" for the 1975-79 Khmer Rouge reign of terror, one of the darkest chapters of the 20th century. His appearance at the specially built court on the outskirts of Phnom Penh was a significant step for the tribunal, officials said, after a decade of delays caused by wrangling over jurisdiction and cash. Before his arrest by the court, Duch had been held in a military prison without trial since 1999. His lawyers called this a "violation of international law and Cambodian law". A born-again Christian, Duch has confessed in interviews with Western reporters that he committed multiple atrocities as head of the infamous Tuol Sleng, or S-21, interrogation centre. At least 14,000 people deemed to be opponents of Pol Pot's "Year Zero" revolution passed through Tuol Sleng's barbed-wire gates. Fewer than 10 are thought to have lived to tell the tale. Most victims were tortured and forced to confess to a variety of crimes -- mainly being CIA spies -- before being bludgeoned to death in a field on the outskirts of the city. Women, children and even babies were among those butchered. Outside the court, hundreds of ordinary Cambodians gathered to catch a glimpse of the infamous inquisitor. "Why should we spent so much time waiting until now?" American-Cambodian citizen on Chin asked. Kek Galabru, president of a human rights group in Cambodia, was concerned about the legality of the trial under international law. Duch is expected to be a key witness in the trial of four other top Khmer Rouge officials, including ex-president Khieu Samphan, 78, who was accused of crimes against humanity and war crimes on Monday. Former foreign minister Ieng Sary and his wife -- both life-long friends of "Brother Number One" Pol Pot who died in 1998 -- and "Brother Number Two" Nuon Chea, face similar charges. The four others have denied knowledge of any atrocities as Pol Pot pursued his dream of creating an agrarian peasant utopia.