Khieu Samphan, a leading figure in Cambodia's genocidal Khmer Rouge regime in the 1970s, was arrested Monday and immediately brought before a U.N.-backed tribunal.
The former head of state who served under notorious Khmer Rouge chief Pol Pot was escorted to the tribunal from a Phnom Penh hospital where he had been undergoing treatment since Wednesday after suffering a stroke.
Officers physically supported the 76-year-old as they led him to a police car, which sped away in a heavily guarded convoy.
Khieu Samphan's arrest by the U.N.-backed tribunal had been widely expected. The tribunal, which was created last year after seven years of contentious negotiations between the United Nations and Cambodia, already has arrested four of his colleagues.
Most historians and researchers believe the radical policies of the Khmer Rouge, which sought a utopian communist state, led to the deaths of at least 1.7 million Cambodians through starvation, disease, overwork and execution.
Tribunal spokesman Reach Sambath, who announced the arrest, said Khieu Samphan would be formally charged by investigating judges later in the day. The statement did not say what charges he faced.
The arrests of the Khmer Rouge suspects come almost three decades after the group fell from power, and many fear the aging suspects could die before being brought to justice. After years of delays, the trial is expected to begin in 2008.
Khieu Samphan has repeatedly denied responsibility for any atrocities.
A week ago, authorities arrested Ieng Sary, the Khmer Rouge's ex-foreign minister, and his wife Ieng Thirith, its social affairs minister. Both were charged with crimes against humanity; Ieng Sary was also charged with war crimes. The genocide tribunal formally placed them in provisional detention for up to a year.
Two other suspects - former Khmer Rouge ideologist Nuon Chea and Kaing Guek Eav, also known as Duch, who headed the group's S-21 torture center - were detained earlier this year on charges of war crimes and crimes against humanity.
The tribunal is scheduled to open a hearing Tuesday on an appeal by Duch's lawyers against his detention. The hearing will mark the first-ever courtroom proceeding held by the tribunal.
From NPR reports and The Associated Press