Cambodia's Khmer Rouge tribunal began hearing closing statements Wednesday in its first trial of top leaders of the 1970s communist regime widely considered responsible for the deaths of an estimated 1.7 million people.

Nuon Chea, the regime's chief ideologist, and Khieu Samphan, its head of state, are charged with genocide and crimes against humanity — including torture, enslavement and murder — for planning and implementing the group's brutal policies.

The first statements will be from lawyers for "civil parties" participating in the trial to represent the victims. Statements from the prosecution and defense are scheduled through the end of October, and a verdict is expected in the first half of 2014.

The Khmer Rouge, in power from April 1975 to January 1979, emptied the country's cities, forcing Cambodians into backbreaking work in rural collectives and executing any it suspected of dissent.

Torture and death by starvation, lack of medical care, overwork and execution, were endemic under the secretive Khmer Rouge, who virtually sealed off their country from the rest of the world. The present trial's focus on the forced movement of people excludes some of the gravest charges related to genocide, detention centers and killings.

To make a massive indictment more manageable, the court decided in 2011 to split the case into smaller 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.

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 dropped from the trial in September 2011 after being diagnosed with dementia.

The tribunal has ruled that the next trial, to hear the charges of genocide, will begin as soon as possible after the present trial's closing statements, but tribunal spokesman Lars Olsen said no schedule had been set.

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. Cambodia has no death penalty.

Proceedings have been hampered by underfunding, and obstruction by the government of Prime Minister Hun Sen, who counts surrendered Khmer Rouge leaders among his political allies. He himself defected from the group at an early stage.

Since the current trial's opening statements in November 2011, the court has heard testimony from 92 individuals over 212 days. By the court's estimate, nearly 100,000 visitors have attended the proceedings, largely Cambodians the court bused from the countryside as part of a broad effort to promote awareness of the justice process.