Core Activities


The OCP participates in the two stages of the investigation phase at the ECCC. In the preliminary investigation, the Co-Prosecutors carry out initial inquiries to determine whether there is evidence to indicate crimes under the jurisdiction of the ECCC have been committed. If the Co-Prosecutors have reason to believe that crimes have been committed, they may open a judicial investigation into these allegations by forwarding an Introductory Submission to the Co-Investigating Judges (“CIJs”). This submission is a request to the CIJs to investigate the allegations made by the Co-Prosecutors. 

The judicial investigation begins upon the CIJs’ receipt of the Introductory Submission from the OCP. In this stage, the CIJs are solely responsible for investigating the allegations made by the Co-Prosecutors. The Co-Prosecutors, civil parties and/or charged person(s) may request that the CIJs undertake particular investigative acts. At the end of the judicial investigation, the OCP prepares a Final Submission based on the evidence collected, either asking the CIJs to indict the charged person or, alternatively, to dismiss the case. The CIJs then issue a Closing Order to send the Charged Person(s) to trial or to dismiss the case. Throughout the judicial investigation phase, the Co-Prosecutors and other parties may request that the Pre-Trial Chamber review decisions of the CIJs.


The OCP participates in the trial and appeal phase of the judicial process. At the trial stage, before the trial commences, the Co-Prosecutors provide the Trial Chamber with a list of witnesses and experts they wish to testify and a list of documents they wish to admit as evidence. During trial, the Co-Prosecutors question witnesses, civil parties, experts and the accused, if the accused gives evidence, as well as present legal and factual arguments on the evidence and the charges. At the beginning and end of the trial, the Co-Prosecutors may give opening and closing statements summarising their case. They may also submit a written Closing Brief that comprehensively presents the evidence on all charges being considered by the Trial Chamber.      

In the appeal stage, following the judgment of the Trial Chamber, the Co-Prosecutors may appeal or respond to an appeal by the Defence to the Supreme Court Chamber. Parties may only appeal where an error of fact or law leads to a miscarriage of justice. The appealing party must provide a notice of the grounds of appeal and submit an Appeal Brief setting out the arguments and authorities in support of each ground. The Co-Prosecutors or other parties may respond to the appeals through a written Response Brief and oral arguments.


The OCP aims to promote reconciliation for the crimes committed during the Khmer Rouge period and help strengthen the rule of law and fair trial process in Cambodian courts through its outreach program. This involves participating in regular outreach activities communicating the work of the Court, both substance and procedural, to various audiences. These include interested Cambodian citizens travelling from Phnom Penh and provinces across the country, university and school students, law students, judicial trainees and judges and prosecutors from Cambodia and abroad. They also include government and NGO representatives, particularly those dealing with mass crimes, transitional justice and human rights. All staff participate in these activities and, whenever possible, interns are also encouraged to become involved.

Capacity Building

A core goal of the OCP is to promote capacity building with national and international staff and interns.  In this hybrid office, national and international staff build each other’s capacity in their areas of expertise, whether it be Cambodian or foreign legal traditions, technology, cross-cultural skills, or advocacy. Similarly, the national and international OCP interns work closely with experienced staff members, enabling each intern to further develop their legal skills and understanding of international criminal justice.