A former guard at Tuol Sleng prison told the Khmer Rouge tribunal he had suffered much and feared for his life at the prison, as other guards disappeared, in testimony that was roundly rejected by the defendant, Duch, on Monday.

Kok Sros, 59, told judges at the UN-backed court he and other guards “tried to work hard and waited for whatever would happen to us.”

Kok Sros said he worked as a security guard at Tuol Sleng, known to the Khmer Rouge as S-21, where prosecutors say 12,380 people were sent to their deaths under Duch, whose real name is Kaing Kek Iev.

“I had too much suffering while working at S-21, but we did not know where to escape,” Kok Sros said.

While on guard at the prison from 1975 to 1979, Kok Sros said he had seen many prisoners hand-cuffed in single cells and heard from other guards that some inmates had committed suicide.

Tuol Sleng was a main torture facility for perceived enemies of the ultra-Maoist revolution, and Kok Sros said some of its victims asked him to help them. He told them he could not.

Nor was the prison safe even for guards. Two of his crew of 10 disappeared from the prison, Kok Sros said, adding that their disappearances made him fearful and that he worried he himself would be killed.

Duch, whose real name is Kaing Kek Iev, rejected the testimony, saying he did not believe Kok

Sros was a guard at the prison. He said he never visited detention rooms as described by the witness.

Duch is facing charges of war crimes, crimes against humanity, torture and murder for his role as prison administrator, in a trial that has been running for more than three months now.

He is the first of five jailed leaders of the regime to face trial at the joint UN-Cambodia court.