For nearly four decades, has sat at the intersection of memory and mathematics. As the chief document examiner and senior investigator for the Documentation Center of Cambodia (DC-Cam) , his life’s work has been to count the uncountable: the 1.7 million to 2.2 million Cambodians who perished during the Khmer Rouge regime (1975–1979).
Chheng has testified at the ECCC as a factual and expert witness. During one cross-examination, a defense lawyer suggested the documents could have been forged. Chheng responded calmly: "I was there. I held the paper. The paper does not lie. Only people lie." The ECCC concluded its work in 2022 with only three convictions. For many Cambodians, the tribunal was a failure—too slow, too expensive, too limited in scope. But Chheng refuses to see it that way.
"The handwriting was beautiful," Chheng recalls in a rare 2018 interview. "The prisoners were teachers, doctors, poets. They wrote their own death warrants because they were told if they confessed, they would live. They never lived." Chheng’s unique skill is his ability to read between the lines of Khmer Rouge documentation. He doesn’t just translate the words; he decodes the subtext. A "confession" of spying for the CIA was almost always a fabrication. A note that a prisoner was "sent for re-education" was a euphemism for execution.
His meticulous cross-referencing helped build the evidentiary foundation for the —the UN-backed tribunal that finally tried senior Khmer Rouge leaders like "Duch" (Kaing Guek Eav) and Nuon Chea. ly chheng biography
One of his most haunting discoveries was a logbook from a cooperative in Kampong Cham. On a single page, the local chief had recorded the names of 47 people "transferred." In the margin, a tiny code—barely visible—indicated that all 47 were taken to a sandbar and killed with hoe handles. Chheng found the sandbar. Forensic teams found the teeth. To spend a day with Ly Chheng is to understand the psychological weight of his work. He does not cry. He does not raise his voice. He has developed the affect of a coroner: clinical, precise, detached. But the detachment is a survival mechanism.
He paused. Outside, Phnom Penh’s traffic roared—a city of skyscrapers, coffee shops, and teenagers on smartphones who never knew the Year Zero.
"Justice is not just about prison cells," he says. "Justice is about a daughter knowing what happened to her father. Justice is about a village building a stupa of bones so the spirits can rest." For nearly four decades, has sat at the
"I have seen the signature of the man who killed my cousin," he told a Phnom Penh Post reporter in 2012. "I have read the confession of the woman who lived next door to me in Battambang. She confessed to being a Vietnamese spy. She was a rice farmer. She was 22. She had a baby."
He turned back to his desk. On the screen was a scanned confession dated 1977. The prisoner had signed it with a shaky hand. Chheng adjusted the contrast, zoomed in on the signature, and added the name to a database.
Another ghost, accounted for. Another debt, noted. Another day in the life of the man who refuses to let Cambodia forget its dead. During one cross-examination, a defense lawyer suggested the
When prosecutors needed to prove that the regime’s policies amounted to genocide against the Cham Muslim minority and the Vietnamese, they turned to Chheng’s spreadsheets. He created a relational database that matched prison logs with mass grave coordinates. He proved, beyond a reasonable doubt, that the killing was not chaotic but systematic.
That changed in 1995 when Yale University opened the . For the first time, there was a systematic effort to locate, preserve, and digitize the paper trail the Khmer Rouge had left behind. The regime was famously bureaucratic: they kept records of arrests, confessions (often tortured), and executions.
By the time the Vietnamese army toppled the regime in January 1979, Chheng had lost most of his immediate family. He emerged from the camps weighing less than 40 kilograms, an orphan in a country that had been reduced to ash and bone. For a decade after the fall, Cambodia was a nation in shock. The surviving Khmer Rouge leaders retreated to the jungles along the Thai border, and the international community largely looked away. For survivors like Chheng, there was no justice—only the grinding work of rebuilding a life.
When he identified the handwriting of his own primary school teacher on a Tuol Sleng execution order, he closed the file and went for a walk. He did not return to the document for three weeks.
"I learned to watch," he once told a researcher. "If you watched the guards, you could see the violence coming. If you watched the rice, you knew if you would eat. If you watched the sky, you knew when the bombing would stop. Watching became my profession."