Witness Him Huy, chief of the security unit at the infamous S-21 prison, continued testifying before the Khmer Rouge tribunal yesterday, recounting the processing of victims and waffling on prior accounts of the security centre’s chain of command.

Under questioning from prosecutor Travis Farr, Huy said he was “selected to become an interrogator”, but told his superiors that he did not know how to write and therefore could not “make a report of the confessions”.

Instead, he was assigned to be a guard and “saw those people who were arrested and brought to centre”, which he later said included infants and children.

“Children were detained along with their mothers,” he told the court, going on to recall that they were executed behind the prison.

Admitting to carrying children away to be killed, Huy then clarified, “they were babies; they were . . . between 1 month and 7 or 8 years old”.

Farr then moved on to the alleged killing of Vietnamese, reading out the written record of an interview with Huy in which he said that his guard group and that of a cadre named “Peng” carried out executions of Vietnamese soldiers. In court yesterday, however, Huy seemingly distanced himself from such killings, saying his group was simply told to send them away.

Earlier, Huy recalled the study sessions at “the political school located next to Duch’s house”, referring to the former S-21 chief convicted in Case 001, Kang Geuk Eav.

The study sessions included the S-21 staff and workers from nearby rice fields, he said.

Farr also pressed Huy on the S-21 chain of command, starting with Khmer Rouge senior official Son Sen, who purportedly left the prison in 1977. “Son Sen used to come and conduct study sessions for us; we knew that he was Duch’s superior. Later on, he took the forces to fight against the Vietnamese,” he said.

At first claiming he did not know who Duch’s superior was thereafter, Huy later said that Son Sen must have remained above Duch because Duch “made no announcement” to the contrary.

Huy recalled that while at S-21, Duch said that “Brother Number One was Pol Pot and Brother Number Two was Nuon Chea” – one of the defendants, along with former head of state Khieu Samphan, in the current Case 002/02.

Pressed by Farr for details, Huy said this was mentioned at training sessions. Confronted by previous testimony in which he had said brothers number one and two were Duch’s superior, Huy yesterday appeared to change his position.

“I did not hear him say that the two brothers were his superiors,” he said. Before ceding the floor, Farr asked Huy what he knew about Office 870, from which Pol Pot allegedly ordered killings.

“[Duch] mentioned Office 870 in training sessions,” Huy said, but claimed he did not know why. “It was not my responsibility at the time; it was his responsibility.”