The Khmer Rouge’s Tuol Sleng prison chief Kaing Guek Eav, better known as Duch, was discharged from hospital on Monday and is back at the Kandal provincial prison.

He had spent three weeks at the Khmer-Soviet Friendship hospital with respiratory problems.

In 2012, Duch was sentenced to life imprisonment by the Supreme Court Chamber of the Extraordinary Chambers in the Courts of Cambodia (ECCC) for crimes against humanity and grave breaches of the Geneva Conventions of 1949.

He was transferred to Kandal provincial prison in 2013.

Kandal provincial prison chief Chat Sineang said on Tuesday that he had requested his superiors to allow two fellow inmates to stay with Duch to help take care of him.

“On Monday, the hospital issued a letter to allow us to return him to the prison because his health is better.

“He had respiratory problems and the hospital gave us the prescription to buy medicine for him. But they told us to bring him to the hospital immediately if anything happened,” Sineang said.

“In the past, we had put him in a single cell. But because of his health problems, [on Monday] I made phone calls to the prosecutor, the director of the General Department of Prisons and a secretary of state at the Ministry of Interior.

“I asked for permission to let two prisoners with light sentences and who have nearly served their prison terms to stay with him, to take care of him if he is not well. We have to be careful with him because he is [an internationally infamous] prisoner,” Sineang said.

The prison director said he had additionally installed a camera in his cell in case his two prison companions were not alert to any problems.

“I did not hope he would survive,” Sineang told AFP.

“But he has recovered from the illness and he arrived back at the prison on Monday evening.”

However, he said that Duch – who turns 76 in a few days – was still weak and needed help from guards when he wanted to use the bathroom.

The former mathematics teacher who became director of the Khmer Rouge’s S-21 interrogation centre in a former school in the capital’s Chamkarmon district, was the first member of the Khmer Rouge to come before the ECCC, where an appeal in 2012 extended his original 30-year sentence handed down in 2010 to life.

Only 14 people are known to have survived Tuol Sleng, which under Duch’s meticulous and rigid hand evolved into an efficient killing machine that came to symbolise the worst excesses of the Khmer Rouge.

Entire families were imprisoned for the alleged crimes of a single member.

On a single day in 1977, Duch ordered the executions of 160 children.