He attended the prestigious Lycée Sisowath in Phnom Penh from 1946 to 1952,[2] studied in France from 1953 to 1955, then returned to Cambodia to work in the Royal Treasury.
[4] He was appointed State Secretary for Finance but he publicly opposed the decision in November 1963 by Norodom Sihanouk to nationalize banks and foreign trade, and was forced to resign.
On 2 April 1974, he became one of four members of an executive board composed, in addition to Long Boret, of Lon Nol, Sisowath Sirik Matak and General Sosthene Fernandez.
When I personally went to see him on April 12, the very morning of our evacuation, to ask him to take his wife and himself and his young children out of Phnom Penh because I feared for his safety, he thanked me but [said he] thought his life was not in danger.
[7] Both General Sak and the journalist Jon Swain[8] reported that Long and his family were unable to board the last helicopter flying out of the city.
[9] In his memoir, Danger Zones, Ambassador Dean stated that: Long Boret had stayed in Cambodia, thinking that he could have some kind of dialogue with the Khmer Rouge.
Swain reported: ...a black Citroën[11] pulled up and Long Boret got out, his eyes puffy and red, his face empty of expression.
[8]Schanberg gave a more detailed description of the scene: Long Boret arrives in a car driven by his wife...he looks wretched.
[12]Soon after, Koy Thuon, a Khmer Rouge deputy front commander, organized the "Committee for Wiping Out Enemies" at the Hotel Monorom (11°34′12″N 104°55′05″E / 11.57°N 104.918°E / 11.57; 104.918).
11 March 1975 – President Lon Nol orders Prime Minister Long Boret to form a new cabinet and eliminates the post of commander-in-chief of the armed forces.
8 April 1975 – PM Long Boret holds unsuccessful peace talks with Khmer Rouge representatives in Bangkok.