One of the earliest accounts of life under the Khmer Rouge was written in 1973 by a school administrator, Ith Sarin, who had joined the movement after becoming disillusioned with Lon Nol and the Khmer Republic, then rose to the status of candidate member of the KCP, but left the party and returned to Phnom Penh after nine months in the underground. His work, Regrets for the Khmer Soul (in Khmer, Sranaoh Pralung Khmer), it revealed the secrecy with which the Khmer Rouge concealed the existence of the communist party, which they referred to by the sinister term Angkar Loeu (High Organization), or simply, Angkar. The KCP Central Committee was referred to as the Kena Mocchhim (or Committee Machine, mocchhim being derived from the Western term, "machine").

Territories under Angkar control were well organized. Ith Sarin described a five-level hierarchy of Angkar-controlled bodies reaching from the six areas, or phumphaek (see Glossary) into which the country was divided down to the hamlet, or phum level. The Angkar imposed a grim regime in which hatred for Lon Nol, the Americans, and, at times, the North Vietnamese "allies" was assiduously cultivated. Expressions of support for Sihanouk were firmly discouraged and people were encouraged to spy on each other. Discipline was unremittingly harsh. Ith Sarin concluded from his experience that the great majority of the people did not like the Angkar and the collective way of life it imposed, that they despaired that Sihanouk would ever return to power, and that they would support the Khmer Republic if it carried out genuine reforms. Oddly, Lon Nol's security forces banned the book for a time on the grounds that it was "pro-communist." Although this was not true, it did provide a foretaste of what the entire Cambodian population would endure after April 1975.

Disturbing stories of Khmer Rouge atrocities began to surface as the communists prepared to deal the coup de grace to the Khmer Republic. In March 1974, they captured the old capital city of Odongk north of Phnom Penh, destroyed it, dispersed its 20,000 inhabitants into the countryside, and executed the teachers and civil servants. The same year, they brutally murdered sixty people, including women and children, in a small village called Sar Sarsdam in Siemreab Province. A similar incident was reported at Ang Snuol, a town west of the capital. Other instances of what one observer, Donald Kirk, described as a "sweeping, almost cosmic policy" of indiscriminate terror, were recounted by refugees who fled to Phnom Penh or across the Thai border. Kirk contrasted this behavior with the Viet Cong's use of "a modicum of care and precision" in applying terror in South Vietnam (for instance, assassination of landlords or of South Vietnamese officials). Atrocity stories, however, were considered to be anticommunist propaganda by many, if not most, Western journalists and other observers; nevertheless, Phnom Penh's population swelled to as many as 2.5 million people as terrified refugees sought to escape not only the United States bombing and the ground fighting, but the harshness of life under the Angkar.

Data as of December 1987