PHNOM PENH, Cambodia (AP) — Former Khmer Rouge leader Nuon Chea denied all charges against him Thursday on the last day of a trial for the surviving leaders of the 1970s Cambodian regime widely blamed for the deaths of some 1.7 million people.

The ailing 87-year-old Nuon Chea, the Khmer Rouge’s chief ideologist and No. 2 leader, and 82-year-old Khieu Samphan, its head of state, are charged by the Khmer Rouge tribunal with genocide and crimes against humanity. The charges include torture, enslavement and murder for their roles in the radical communist regime nearly 40 years ago.

Nuon Chea, left, who was the Khmer Rouge's chief ideologist and No. 2 leader, waits before his final statements at the U.N.-backed war crimes tribunal in Phnom Penh, Cambodia, Thursday. Pic: AP.

Hundreds of survivors and onlookers crowded the courtroom and the tribunal’s grounds to hear the two aged defendants speak. Khieu Samphan is expected to make his statement later Thursday. A verdict is expected in the first half of 2014, more than two years after the trial began.

Deaths due to execution, disease, torture and starvation were widespread during the Khmer Rouge’s brutal rule in the 1970s, when the communist ideologues emptied cities and forced virtually the entire population to work on farm collectives.

Nuon Chea sat before the court Thursday and denied that he had ordered Khmer Rouge cadres to commit any crimes.

“I never educated or instructed them to mistreat or kill people to deprive them of food or commit any genocide,” said the frail former leader, speaking steadily as he read from pages of notes.

“Through this trial, it is clearly indicated that I was not engaged in any commission of the crimes as alleged by the co-prosecutors,” he said. “In short, I am innocent in relation to those allegations.”

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 declared unfit for trial in September 2012 after being diagnosed with dementia. The group’s top leader, Pol Pot, died in 1998.

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 in 2011. His case was known as 001.

The current trial, Case 002, against senior leaders of the regime, opened in November 2011.

To make a massive indictment more manageable, the court split Case 002 into smaller trials and is examining the evidence in rough chronological order. The present trial’s focus is on the forced movement of people and excludes some of the gravest charges related to genocide, detention centers and killings. The next trial, on genocide and other charges, will begin as soon as possible, but the tribunal has not set a date.

Many fear further trials will never take place, given the slow pace of the proceedings and the poor health of the aging defendants.

Two further cases against a Khmer Rouge military commander and three mid-level cadres are still in the investigation stages, having been obstructed by the government of Prime Minister Hun Sen. The premier counts surrendered Khmer Rouge leaders among his political allies, and he himself defected from the group part way through its time in power.