The first testimony relating to charges of the alleged genocide of ethnic Vietnamese were heard yesterday at the Khmer Rouge tribunal, with witness Sien Sung telling the court of atrocities he witnessed in Siem Reap’s Chi Kraeng district as a teenager.

Sung was 15 years old when the Khmer Rouge took control of Cambodia in 1975. In a village in Chi Kraeng’s Sangvoeuy commune, he recalled witnessing the massacre of ethnic Vietnamese who were brought to the nearby Wat Khsach pagoda.

“I was in a mobile [work] unit and on the way home I witnessed what happened there,” he said, when asked by prosecutor Vincent de Wilde whether he knew of a massacre at the pagoda in 1978.

Sung said he lived near the pagoda, which was used as temporary housing for workers before the massacre.

“I saw Vietnamese people being killed and dropped into a pit,” he said.

Sung said he had heard that people “were transported by ox carts” to the pagoda, and that those people were Vietnamese.

“They were killed the night they arrived,” he added.

Observing the massacre that night from a pit, at a distance of 30 metres, Sung said he heard crying. When asked by de Wilde whether he was concerned about putting himself at risk, Sung said he “knew it was risky”.

There had also been an adult watching alongside him, he later added, and it was “with his presence that I dared to look at the incident”.

Illuminated by kerosene lamps, the killing could be seen clearly, Sung said, although he couldn’t make out the facial expressions of the victims.

According to Sung, cadres asked the victims whether they were Chinese or Vietnamese.

“Those that said they were Vietnamese, they were killed at the pit,” he said, while those claiming to be Chinese were taken away and later released.

Victor Koppe, Nuon Chea's defender, then interjected to request that Sung’s wife, practically the only person in the audience, be removed from the courtroom, as he held she could potentially be called later to testify herself, causing a possible conflict of interest.

Wilde, however, dismissed Koppe’s reasoning as “flimsy”, and the judges denied the request.

Sung testified that the victims, including children, were killed using “bamboo sticks around 70 centimetres in length”, but some of the children were killed by other methods.

“Children were thrown up into the air, and when they fell down into the pit, they fainted and collapsed, and perhaps they died afterwards.”