After witness testimony, former S-21 chief says he is 'top criminal' solely responsible for atrocities committed at Tuol Sleng prison.

IN RESPONSE to witness testimony, former Tuol Sleng prison chief Kaing Guek Eav, alias Duch, declared himself to be the "top criminal" responsible for atrocities committed at the secret detention facility.

"I am the top criminal responsible for all crimes committed at S-21, responsible for the lives lost at S-21," Duch said, adding that he was "committing myself firmly to be responsible solely before the law".

His statement came after the court heard further testimony from Sous Thy, 58, who said on Monday that he had been tasked with registering detainees as they arrived at the prison.

Sous Thy told the court on Tuesday that he felt regret for the people who were killed at the prison.

He also said that S-21 staff "disliked" working at the prison but obeyed orders out of fear.

"S-21 staff disliked their regime at the time, and that is the truth," Sous Thy said.

"What I did at S-21, it was under instructions from the upper echelons.... I needed to perform, and if I did not do it, I would be punished. I am really regretful and pitiful of those people who were arrested and killed."

Duch, who was called on to make observations on the witness's testimony, said Sous Thy's comments "reflected the truth", and that he admired the witness for bringing honesty to the chamber.

"I really appreciated his spirit of honesty to the chamber by speaking out the truth," he said.

Prisoners 'malnourished'

Speaking on the second day of his testimony, Sous Thy told the tribunal that the detainees at Tuol Sleng prison were starving and living in misery.

"When I would go to verify the list of prisoners inside the prison cell, I did not pay great attention to their condition, although I knew that they suffered a great deal because most of them were very thin and the majority of them were so skinny and malnourished," Sous Thy said.

"I may say there was not significant ventilation or air circulation inside the room," he added.

But Sous Thy said he had tried to focus primarily on his job, and that the bulk of his observations stemmed from the brief periods in which prisoners were herded from their cells into trucks for execution.

"I could only see that they were very weak," he said.