The Co-Prosecutors must file their full appeal brief before Sept. 10. The defense will then have 15 days to respond, said court spokeswoman Helen Jarvis. The Pre-Trial Chamber will make the final decision involving the scope of Duch's criminal liability.

While the closing order currently contains charges that could lead to Duch's conviction, it is the court's mandate "to ensure the recording of a full and truthful account of the crimes of the Khmer Rouge and the individual criminality of those responsible for them," according to the Co-Prosecutors.

Jarvis said she did not believe the appeal "would significantly impact" the start of Duch's much-anticipated trial.