A former messenger yesterday told the Khmer Rouge tribunal he had happily driven his superiors to a plane bound for Phnom Penh, only to learn later some of them were being flown to their deaths.

The witness, whose name remains confidential because of his role in ongoing investigations into cases 003 and 004, said 11 of his leaders in Kratie district were summoned to the capital in a mysterious letter from the communist party’s leadership.

“I was so delighted after my leaders had gone away, since I had time to go and visit Mondulkiri [for two days],” he said, adding as he was quite young, he relished the free time. But when he returned to Kratie, he was shocked to find his commanders had been replaced.

Meas Muth, the defendant in Case 003, who the witness yesterday named as the deputy commander in chief of the general staff and navy official, then convened a meeting with 70 other cadre.

“We were told all our leaders were traitors,” the witness said.

The prosecution produced documents showing six of the 11 were sent to S-21 in December 1978 and executed – just weeks before Vietnamese forces arrived in Phnom Penh and forced the Khmer Rouge to flee.

Others, the witness said, were rumoured to have been sent to a worksite at Kampong Chhnang airport. According to the witness, Muth said his superiors had not fought viciously enough against the encroaching Vietnamese troops.

“Back then, we did not dare to protest [against Muth] … [even though the Vietnamese] had new and modern weapons and . . . bigger forces,” he said.

After hearing the message from Muth, the witness said “we felt hatred in our hearts” and they fought harder at the border. “Our units were trying our best; we really wanted to defeat the yuon,” he said, using term for the Vietnamese considered derogatory by some.

The witness, who remained in the Khmer Rouge until the late ’90s, said he was close to former leader Ta Mok, who died in 2006 awaiting trial. He defended Ta Mok against the nickname by which he has become known in the popular imagination – “the butcher”.

“He was not a killer or executioner,” the witness said, after he testified on Tuesday that Ta Mok was “loved” by soldiers and ordinary people alike.