UN-backed Khmer Rouge tribunal is starting full hearing on genocide trial

In this photo released by the Extraordinary Chambers in the Courts of Cambodia, Nuon Chea, who was the Khmer Rouge's chief ideologist and No. 2 leader sits in a court room of the U.N.-backed war crimes tribunal, in Phnom Penh, Cambodia, Thursday, Jan. 8, 2015. The U.N.-backed war crimes tribunal on Thursday began its evidence hearing in the second trial against the two most senior surviving leaders of the Khmer Rouge regime, Khieu Samphan, former Khmer Rouge head of state, and Nuon Chea, who was the Khmer Rouge's chief ideologist and second in-command. The two octogenarians are facing charges of genocide, war crimes and crimes against humanity. (AP Photo/Extraordinary Chambers in the Courts of Cambodia, Nhet Sok Heng) (The Associated Press)

In this photo released by the Extraordinary Chambers in the Courts of Cambodia, Khieu Samphan, former Khmer Rouge head of state, sits in a court room of the U.N.-backed war crimes tribunal, in Phnom Penh, Cambodia, Thursday, Jan. 8, 2015. The The U.N.-backed war crimes tribunal on Thursday began its evidence hearing in the second trial against the two most senior surviving leaders of the Khmer Rouge regime, Khieu Samphan, former Khmer Rouge head of state, and Nuon Chea, who was the Khmer Rouge's chief ideologist and second in-command. The two octogenarians are facing charges of genocide, war crimes and crimes against humanity. (AP Photo/Extraordinary Chambers in the Courts of Cambodia, Nhet Sok Heng) (The Associated Press)

Court officer Neth Pheaktra, right, gives a court pass to participants as they line up in front of an entrance at the U.N.-backed war crimes tribunal in Phnom Penh, Cambodia, Thursday, Jan. 8, 2015. The U.N.-backed war crimes tribunal on Thursday began its evidence hearing in the second trial against the two most senior surviving leaders of the Khmer Rouge regime, Khieu Samphan, former Khmer Rouge head of state, and Nuon Chea, who was the Khmer Rouge's chief ideologist and second in-command. The two octogenarians are facing charges of genocide, war crimes and crimes against humanity. (AP Photo/Heng Sinith) (The Associated Press)

Cambodia's Khmer Rouge tribunal restarted genocide hearings Thursday against the former regime's most senior surviving leaders, with the first witness being called to testify against the ailing octuagenarians.

Proceedings had been postponed since November after defense lawyers threatened a boycott because they said they were still working to appeal an earlier verdict.

Khieu Samphan, the 1970s regime's head of state, and Nuon Chea, a right-hand man to communist group's late leader, Pol Pot, were sentenced to life in prison in August after being found guilty of crimes against humanity. They are now on trial on separate charges of genocide against minorities, and rape and forces marriages — the first time such accusations have been put to trial.

Some 1.7 million people are estimated to have died from starvation, disease and execution due to the group's extremist policies, and there is growing concern that the two men could die before the genocide trial can be completed.

Thursday's hearing ended early, at midday, because Khieu Samphan, 83, was dizzy and suffering from high blood pressure. Nuon Chea, 88, did not appear in court and watched the proceedings via a video link from a holding cell due to his poor health.

The witness who testified on Thursday, 55-year-old Meas Sokha, was one of several dozen survivors who are expected to give their accounts before the court.

Responding to questions from prosecutors, Sokha said 12 of his relatives, including his parents, were arrested. He said several of them were executed by authorities.