Three civil parties told the Khmer Rouge tribunal yesterday of the murders of numerous family members by the regime that ruled Cambodia between 1975 and 1979.

Former Khmer Rouge cadre Chhay Heab, 55, testified that five of his eight siblings were killed at Phnom Penh’s notorious S-21 prison. Among them were his eldest brother Heay, a fellow revolutionary, who was accused in 1977 of being a traitor when the regime’s far-reaching internal purges were underway.

“It was not long after the arrest of my brother that his wife and children were also arrested,” Heab said, explaining that they were taken away “just because their father was arrested”.

“We were unfortunate to be born and live through such a regime,” the former child soldier said.

The UN-backed tribunal is hearing evidence in the second part of its lengthy case against the two surviving senior leaders of the Khmer Rouge: Nuon Chea, who was deputy leader, and former head of state Khieu Samphan. Both defendants, who are in their eighties, have denied all charges.

In recent weeks, the tribunal has heard testimony about the extensive internal purges that saw Pol Pot’s paranoid government murder its own supporters and, in many cases, their families, too. Most of the prisoners taken to S-21, for instance, were Khmer Rouge cadres who came under suspicion.

Phuong Yat told the court how she lost most of her siblings. One sister disappeared, and four brothers were executed at S-21. When she saw their pictures at the prison, she said, “I wept to the point that I almost lost consciousness.” Another of Yat’s sisters fled and was hidden by villagers after cadres ordered her to marry against her will.

The third civil party, Ros Chuor Siy, testified she was living in Paris with her family when Phnom Penh fell in 1975. Khmer Rouge foreign minister Ieng Sary, who died in 2013 while on trial, regularly travelled abroad asking Cambodians to return on the duplicitous grounds that they would help rebuild the country. Siy said Sary managed to convince her and her husband to come back.

Siy’s husband, who had previously been the director of Phnom Penh’s airport, was put to work doing manual labour at the Boeung Trabek camp in the capital. He became emaciated and weak, she said, and was ordered to be “relocated”. After the regime was driven from power in 1979, Siy went to S-21.

“I saw people that I knew amongst the photos. Then I saw my husband,” she testified. “I saw torture instruments that I’d rather not describe. I could not imagine what harm, torture and suffering was inflicted upon him before his death.”