The tribunal has spent around $150 million since 2003, and began operation in 2006.
Court officials have denied any political influence in cases 003 and 004.
Former leaders Noun Chea, Khieu Samphan, Ieng Sary and Ieng Thirith have all denied atrocity charges.
Now 69, she suffers from knee problems, poor eyesight and insomnia, according to her lawyers.
The Center for Justice and Accountability is helping organize applications for victims of the regime who fled to the US.
Khieu Samphan acknowledged the Cambodian people had a pressing need to know what had happened.
Khieu Samphan also pleaded with the court to allow the witnesses submitted by his defense team.
A preliminary hearing this week has brought the amnesty deal made in 1996, to the forefront.
In his award-winning documentary, “Enemies of the People,” Thet Sambath faces Nuon Chea and asks why some people were killed.
During the Khmer Rouge rule, fear descended on villages as people were accused of being counter-revolutionaries and began disappearing.
In one of the last strongholds of the Khmer Rouge, some Cambodians still consider Pol Pot a powerful figure to be worshipped.
All four have said they are innocent of the charges against them, including war crimes, crimes against humanity and genocide.