|Ieng Sary, the former Khmer Rouge foreign minister, is one of four indicted by the UN-backed tribunal [EPA]
Cambodia's war crimes tribunal has indicted the four remaining survivors of the Khmer Rouge regime, effectively paving the way for a trial next year.
The UN-backed tribunal said on Thursday that it expects to start the trial by the middle of next year. Facing charges are Nuon Chea, the group's ideologist; Khieu Samphan, the former head of state; Ieng Sary, the former foreign minister, and his wife Ieng Thirith, a former minister for social affairs.
According to You Bunleng, the co-investigating judge, each defendant faces four counts, including crimes against humanity, genocide, war crimes and a combined charge of murder, torture and religious persecution.
Investigating judges have interviewed the suspects 46 times since being detained by the tribunal in 2007.
The group's chief jailer, Kaing Guek Eav, also known as Duch, was convicted earlier this year of war crimes and crimes against humanity. He is serving a 19-year sentence.
Duch was the first defendant to be tried. He supervised the notorious S-21 prison where as many as 16,000 people were tortured before being executed.
Also found guilty of torture and murder, Duch was originally sentenced to 35 years in prison. Jail time he previously served reduced the sentence to 11 years, and he was compensated five years for illegal detention in a military prison.
The length of Duch's sentence was widely criticised as too short and prosecutors are appealing for a longer sentence, saying the judgement "gives insufficient weight to the gravity of Duch's crimes."
Duch has also filed his own appeal, seeking acquittal for what he says were legal errors made by the tribunal.
The judges presiding over Duch's case said they took into consideration the historical context of the Khmer Rouge atrocities, and they also recognised that Duch - unlike any of the others in detention - was not in the Khmer Rouge's inner circle. He also cooperated with the court and shown expressions of remorse, however "limited."
But they flatly rejected Duch's claims that he was merely acting on orders from the his superiors, or that he was a "cog in the machine'' who could not get out.
The Khmer Rouge, led by Pol Pot, emptied Cambodia's cities during its 1975-1979 rule, exiling millions to vast collective farms in a bid to take society back to "Year Zero" and forge a Marxist utopia.
At least two million people were executed in the notorious "Killing Fields" or died from starvation and overwork before Vietnamese-backed forces toppled the government.