Former S-21 prison chief Kaing Guek Eav was probed on the arrests of upper level Khmer Rouge cadre suspected of spying for Vietnam and planning a coup d’état against the Pol Pot regime at the Khmer Rouge tribunal yesterday.

Touching on an issue key to the defence of co-accused Nuon Chea – the regime’s former “Brother number two” – Eav, better known as Duch, was confronted with questions about alleged Vietnamese infiltration into the ranks. The Chea defence has argued that the Khmer Rouge was riven by competing factions, and faced a legitimate threat from Vietnam – a threat that Duch obliquely acknowledged.

Questioning briefly touched on former North West Zone secretary Koy Thoun, who was arrested in early 1977 and upon whose confessions of plotting against the regime later purges were allegedly based.

Duch said he had personally interrogated Thuon without resorting to torture.

“It was an absolute order not to commit torture . . . against him,” Duch said. “Since I was once his subordinate . . . I was ordered not to be convinced by Koy Thuon and I had to be strong in my stance.”

He said Koy Thuon was permitted to sit on a bed while questioned, and Duch ordered guards to watch over him after Thuon “became very angry, and broke the eyeglasses and threw away the pen”.

“I ordered them not to inflict any torture, and prevent him from committing suicide,” Duch said.

But when Nuon Chea defender Victor Koppe asked Duch if he knew the reasons for Koy Thuon’s arrest and execution, Duch deferred to the party line.

“The reason, during the Khmer Rouge regime, was simply anyone who [was] considered an enemy was to be smashed,” he said.

Koppe again cast doubt on the extent of Duch’s knowledge, pointing out that Duch was holed up in his house day and night, trawling through the reams of “confessions” extracted from prisoners.

Duch, referring to himself in the third person, admonished the implication.

“Head of S-21 was not a stupid person . . . head of S-21 knew everything,” he said.

Koppe then turned to an assessment by academic William Duiker, who wrote that Vietnam, after it had planted seeds for a general uprising that was thwarted by the death of Khmer Rouge East Zone leader Sao Phim, opted for an outright invasion of Democratic Kampuchea.

“Rebel forces in Cambodia would take part in the attack and provide a cloak of legitimacy,” Duiker wrote. Duch said the statement was “consistent with the true situation of the time”.