Nuon Trech was born in Trapeang Chuk Village in Steung Trong District, Kampong Cham Province. He joined the army when he was 15. Oeun was his Division 310 commander and Voeung his deputy. He worked as a medic before 1975, although he never received any training. He worked at the district hospital at Chamkar Leu. In 1975, he was transferred to the Zone General Staff Hospital. When Phnom Penh was liberated, he was transferred to K-99, and then to a military hospital. He was responsible for treating wounded soldiers and people with malaria. He worked there for nearly one year and was then transferred to Battalion 314. He was arrested at this place, being accused of treason.
According to the witness’ recollection, Battallion 314 and other regiments were convened to a meeting at a school north of Wat Phom. They were told that their leaders were traitors and that they should remain calm. They heard over a loudspeaker a confession of Commander Oeun. Trech returned to his unit and leaders were arrested from time to time, alongside their wives. They were told that they were reassigned to other locations. He first thought that he himself was simply reassigned to another location and not arrested. He was sent to a cell, believed to be in Tuol Sleng, until Yeat took him out. He then went back to continue working as a medic.
Afterwards he was linked to the “enemy network” and transferred to Kampong Chhnang Airfield for re-fashioning. As a prisoner, he was also told to burn explosives in the mountain and break stones to build the airport. Other prisoners working were badly injured and even killed by the explosives. They worked from 4am until 11am. They had a break for an hour and then worked from 12pm until 5pm. They worked every night from 6pm until 10pm. He never returned to Tuol Sleng after 1979.