The chief of a notorious torture center goes before Cambodia's genocide tribunal on Tuesday for its first trial over the deaths of an estimated 1.7 million people at the hands of the Khmer Rouge regime more than three decades ago.

Kaing Guek Eav - better known as Duch, who headed the S-21 prison in Phnom Penh - is charged with crimes against humanity, and is this first of five defendants scheduled for long-delayed trials by the UN-assisted tribunal. The hearing opening today was for procedural matters, and testimony was expected to begin only in late March.