"We ask you for justice justice for the victims who perished, justice for the victims who survive today, who had to live through such a vicious and cruel regime," she said. "The prosecution requests the trial chamber and your honors to punish the accused Nuon Chea and Khieu Samphan with life imprisonment."
The U.N.-backed trial is scheduled to conclude this month after closing arguments from defense lawyers and possible statements from the defendants themselves. A verdict is expected in the first half of 2014, more than two years after the trial began.
Death and disability have robbed the tribunal of other defendants. Khmer Rouge Foreign Minister Ieng Sary died in March, and his wife Ieng Thirith, the regime's social affairs minister, was declared unfit for trial in September 2012 after being diagnosed with dementia. The group's top leader, Pol Pot, died in 1998.
The tribunal, launched in 2006, so far has convicted only one defendant, Khmer Rouge prison director Kaing Guek Eav, who was sentenced to life imprisonment in 2011. His case was known as 001.
The current trial, Case 002, against senior leaders of the regime, opened in November 2011.
To make a massive indictment more manageable, the court decided to split Case 002 into smaller "mini trials" that would examine the evidence in rough chronological order. It was feared that the aging, infirm defendants might not survive long enough to complete more comprehensive proceedings, depriving victims of even a modicum of justice.
The present trial's focus is on the forced movement of people and excludes some of the gravest charges related to genocide, detention centers and killings. The tribunal has ruled that the next trial, on genocide and other charges, will begin as soon as possible but has not set a date.
Hundreds of survivors and onlookers crowded the courtroom and the tribunal's grounds on Monday to hear the prosecutors' request.
Among them was 68-year-old Im Hun, who traveled to the capital from the eastern province of Prey Veng.
"They committed huge crimes and they deserve life imprisonment," said Im Hun, who lost his wife and 10 family members during Khmer Rouge rule. "But these two men are still lucky because they received a fair trial, unlike all the people the regime killed without allowing any of them to speak or defend themselves."