A former radio communications worker and interrogator at the Au Kanseng security centre was questioned at length by prosecutors on internal meetings and “re-education” techniques at the Khmer Rouge tribunal yesterday.

Dressed in a striped white shirt and oval glasses, the anonymous witness gave his testimony via video link in the current Case 002/02 against former Khmer Rouge leaders Noun Chea and Khieu Samphan.

The witness – who was only identified as Witness 2-TCW-900 – detailed how he took notes during interrogations at the prison, where he estimated hundreds of people were killed between 1977 and 1978 while he was stationed there.

Although he said he could not recall the precise number of those who perished at the “re-education centre”, he said only a handful – about 10 – died of illnesses such as malaria or dysentery, while the vast majority of the deceased were “smashed”.

When asked whether he had seen or read written confessions used by the chief interrogator, the witness spoke of the culture of fear, paranoia and distrust within the centre.

“I myself had to be careful in what I said or what I asked,” he said. “If I wanted to know more about … other people, it means I put my security at risk.”

The witness said he became a revolutionary solider in 1970 and was transferred to the prison in 1977, after a stint establishing radio communication posts for the Khmer Rouge in Phnom Penh.

As previous prisoners have testified, the witness confirmed some 100 ethnic Jarai people were brought to the cramped Au Kanseng centre before being executed en masse.

“I can recall the instruction about the ethnic Jarai . . . After hearing the report, [my superior] summed up the report and said, ‘Please solve it’,” the witness said.

“It was our understanding that that the words ‘solve it’ meant ‘kill’.”

Prior to the witness taking the stand, the prosecution asked the court to consider including two more witnesses to give additional testimony on the topic of the Phnom Kraol security centre, as half of their intended witnesses were now deceased.

But Anita Guisse, defence counsel for Khieu Samphan, objected, stating it was a “tardy” attempt by the prosecution to “adjust” the evidence and “prolong indefinitely” the proceedings.

The trial continues today.