Az ECCC khmer és nemzetközi vizsgálóbírói négy magasrangú volt vörös khmer vezetőt gyanúsítottak meg:
"Given the magnitude of the crimes committed under the Democratic Kampuchea regime, between 17 April 1975 and 6 January 1979 (which, according to the demographic survey produced during the investigation, resulted in millions of victims, including an estimated 1.7 to 2.2 million deaths, of which approximately 800,000 were violent), the Co-Prosecutors only seized the Co-Investigating Judges of a specific selection of sites and criminal activities. The judicial investigation thus focused in particular on the following issues:
- The displacement of the population (on three occasions) from urban to rural areas, then between rural areas;
- The establishment and operation of cooperatives and worksites (six sites);
- The reeducation of "bad elements" and the elimination of "enemies", in security centres and execution sites (eleven security centres and three execution sites);
- Crimes against specific groups, including the Cham, the Vietnamese and Buddhists;
- The regulation of marriage.
At the close of the investigation, the Case File contained:
- 46 written records of interview with the Charged Persons;
- over 1,000 written records of interview of witnesses and Civil Parties;
- 36 site identification reports, a demographic expert report, numerous medical reports, and
- over 11,600 pieces of documentary evidence relating to the facts of the case.
The whole Case File extends to over 350,000 pages, more than 223,000 of which relate to substance.
In addition, the Co-Investigating Judges have ruled on the admissibility of 3,988 Civil Party applications. 2,123 applications have been declared admissible . The remaining applications (which, for the most part, were not accepted because the harm suffered by the victims was not directly related to the specific facts of which the Co-Investigating Judges were seized) have been kept on the Case File for information, given the important details they contain, along with over 4,000 victims' complaints already placed on the Case File by the Co-Prosecutors."