Ieng Sary, who served as foreign minister in Cambodia's brutal Khmer Rouge regime, was brought before the country's U.N.-backed genocide tribunal with his wife Monday to face charges of crimes against humanity and war crimes.

Ieng Sary and his wife Ieng Thirith, who was minister for social affairs in the 1975-79 Khmer Rouge government, were served with arrest warrants at dawn at their comfortable residence in the Cambodian capital Phnom Penh, and driven to the tribunal's office. They are being held overnight pending further questioning.

Their detentions bring to four the number of people arrested by the tribunal, officially called the Extraordinary Chambers in the Courts of Cambodia.

The radical policies of the communist Khmer Rouge are widely blamed for the deaths of some 1.7 million people from starvation, disease, overwork and execution. None of the group's leaders have faced trial yet.

The arrests came almost three decades after the Khmer Rouge fell from power, with many fearing that the aging suspects may be claimed by death before they ever see a courtroom. Trials are expected to begin next year.

At a trial conducted in 1979 under the auspices of Vietnam, which invaded Cambodia to oust the Khmer Rouge, Ieng Sary was sentenced to death in absentia. But the proceedings, in the fashion of a Soviet show trial, served the purposes of propaganda more than justice.

Because the U.S. and China opposed the government installed by the Vietnamese in 1979 — and supported a resistance coalition in which the Khmer Rouge played a part as the country's official representative at the United Nations — there was little significant backing for a genocide trial of Khmer Rouge leaders, even as the scale of the horrors they perpetrated became more obvious.

Only when the Khmer Rouge failed to honor a 1991 U.N.-brokered peace agreement and became more clearly an international pariah did the idea of an international genocide trial gain traction. When the ultimate downfall of the guerrilla group became obvious in 1997 — and Prime Minister Hun Sen felt secure against other rivals — Cambodia finally broached the idea.

The U.N.-assisted tribunal was created last year after seven years of contentious negotiations between the United Nations and Cambodia.

Ieng Sary and his wife were members of the inner circle of the communist ruling group, French-educated like its charismatic leader, the late Pol Pot, whose radical vision resulted in waves of deadly political purges. The connection was made intimate by marriage: Ieng Thirith's sister Khieu Ponnary was Pol Pot's first wife.

Besides being deputy prime minister and foreign minister, Ieng Sary was a member of the policy-making central committee. But he has also been accused of being personally responsible for luring home diplomats and intellectuals from overseas to join the revolution after the 1975 Khmer Rouge victory over a pro-American government.

The returnees were arrested and put in re-education camps, and most were later executed.

Ieng Sary, "promoted, instigated, facilitated, encouraged and/or condoned the perpetration of the crimes" when the Khmer Rouge held power, according to a July 18 document presented by the tribunal's prosecutors to its investigating judges, a copy of which was obtained by The Associated Press. The tribunal is being conducted under Cambodian law, which follows the French model.

It said there was evidence Ieng Sary helped plan, direct and coordinate the Khmer Rouge "policies of forcible transfer, forced labor and unlawful killings."

"I have done nothing wrong," Ieng Sary, 77, told The Associated Press in October in Bangkok, Thailand, where he was visiting for a medical checkup.

"I am a gentle person. I believe in good deeds. I even made good deeds to save several people's lives (during the regime). But let them (the tribunal) find what the truth is," he said without elaborating.

The alleged crimes of his wife, Ieng Thirith, who is believed to be 75, included her participation in "planning, direction, coordination and ordering of widespread purges ... and unlawful killing or murder of staff members from within the Ministry of Social Affairs," the prosecutors' filing said.

When the Khmer Rouge lost power in 1979, Ieng Sary retreated with them to the jungles, their base for a guerrilla war. In 1996, with the group's forces in sharp decline, Ieng Sary defected to the government with a large coterie of followers, effectively setting the stage for the total collapse of the Khmer Rouge two years later.

The decision to break away from his comrades-in-arms earned Ieng Sary a limited amnesty from then-King Norodom Sihanouk — but one that officials have declared does not apply to the tribunal's charges.

Youk Chhang, director of the Documentation Center of Cambodia, an independent group documenting Khmer Rouge atrocities, said that prior to his arrest, Ieng Sary had been "the most politically untouchable Khmer Rouge leader."

The other Khmer Rouge in the tribunal's custody are Nuon Chea, the group's former ideologist, and Kaing Guek Eav, also known as Duch, who headed the Khmer Rouge S-21 torture center. They were charged with war crimes and crimes against humanity after being detained earlier this year.

According to the prosecutors' papers made available to the AP, the fifth suspect they seek to charge is Khieu Samphan, another veteran communist who had been the nominal head of state of the Khmer Rouge.