His ability to paint portraits of the then-leader Pol Pot was why he was kept alive.
The Extraordinary Chambers in the Courts of Cambodia, a UN-backed tribunal that sought to try Khmer Rouge leaders for genocide and other crimes against humanity, said he died late Friday due to age-related illness.
"The passing of Mr Bou Meng represents the loss of an important historical witness to the grave crimes committed during the brutal Khmer Rouge regime, particularly to the history and tragedy that took place at the former S-21 Security Centre," referring to the prison, also known as Tuol Sleng, where he had been held for almost two years starting in 1977.
The Khmer Rouge, who ruled Cambodia from 1975–79, were accused of genocide for causing the deaths of so many of their countrymen and women from executions, starvation, and lack of medical care due to their radical policies.
An estimated 1.7 million Cambodians died from forced labour, starvation, medical neglect, and executions.
An estimated 16,000 women and children were kept at S-21 over the course of nearly four years before being killed. Now it serves as the Tuol Sleng Genocide Museum, named after the high school it had been before the Khmer Rouge takeover.
Bou Meng, along with two other survivors, artist Vann Nath and mechanic Chum Mey, testified in 2009 at the trial of Kaing Guek Eav, also known as Duch, who had been the S-21 commander.
Duch was found guilty of crimes against humanity, torture, and murder in 2010 and ultimately received a sentence of life imprisonment. He died in prison in 2020 at the age of 77.
In 2010, Bou Meng testified that painting larger-than-life images of Pol Pot and portraits of other communist icons helped save his life.
It took three months to complete his first outsized work. Kaing Guek Eav then ordered him to make three more Pol Pot paintings and portraits of other communist leaders. These included Mao Zedong of China and North Korea's Kim Il Sung, as well as one mocking Ho Chi Minh, the father of Vietnam's communist revolution.
"I was ordered to paint a picture of Ho Chi Minh's head on the body of a dog," Bou Meng told the UN-backed tribunal.
Cambodia's arch-enemy was neighbouring Vietnam, which eventually invaded to oust the Khmer Rouge in 1979.
Youk Chhang, head of the Documentation Centre of Cambodia, which has collected voluminous archives about the Khmer Rouge tragedy, said on Sunday that Bou Meng's life journey for justice has been documented and "will not be forgotten".
"I urge action to preserve stories of the millions who survived the Khmer Rouge and provide them with both mental and physical health support," Youk Chhang told The Associated Press.
Like many who were taken to Tuol Sleng, Bou Meng had joined the Khmer Rouge in its war from 1970–75 to unseat a pro-American government, but was detained in one of its many internal purges after victory. He was brutally tortured before being assigned his painting duties.
Bou Meng's first wife was arrested with him and disappeared from the prison, and presumably was executed. He never found their two children, who were taken to the countryside, where they were likely killed.
In his later years, Bou Meng, who remarried, often spent his days at the Tuol Sleng Genocide Museum, where he sold copies of a book about his experience.
