Khieu Samphan is one of five senior regime members facing trial on charges of war crimes and crimes against humanity before a United Nations-backed tribunal.
Khieu Samphan was the public head of the Khmer Rogue
He was head of state from 1976 until the Khmer Rouge’s downfall in 1979
After surrendering to the government in 1988, he was arrested on November 19, 2007, at a Phnom Penh hospital where he was being treated for a stroke
Has authored two books in which he denies claims of mass killings and says Pol Pot was responsible for all policies
The tribunal process has been criticised for the long delays in getting started, with critics saying many of the accused and essential witnesses may die before the trials finally begin.
The former Khmer Rouge boss is thought to have suffered another stroke last November.
An estimated one-point-seven million people died of starvation, overwork and execution under the Khmer Rouge.
Pol Pot, the group’s former top leader and so-called Brother Number One died in his jungle hideout in 1998.