The Khmer Rouge tribunal on Wednesday rejected two segments of documentary film provided by the Vietnamese government from the regime’s 1979 ouster, claiming it had gathered enough evidence in the atrocity crimes trial for Duch.

Duch’s notorious Tuol Sleng prison was liberated by Vietnamese forces in January 1979, as combat camera crews recorded the conditions of the facility as they entered. Tribunal prosecutors had entered the films as evidence, but the Trial Chamber of the UN-backed court said Wednesday it would not use them.

“The Trial Chamber finds that the footage in question is likely to have little impact on the trial, as the information it is supposed to provide has already been established though other testimonies and evidence,” according to the court decision. “The Trial Chamber also finds that verification of the reliability of the footage is unlikely to be obtained within a reasonable time.”

The first segment of the footage depicts the overview scenes of the interior of the compound of S-21, including of various types of cells and restraints, as well as images of decapitated corpses chained to beds. The second shows Vietnamese troops helping surviving children leave the prison.

Duch, 66, whose real name is Kaing Kek Iev, is undergoing an atrocity crimes trial for his role as administrator of the prison and torture center, where prosecutors say 12,380 people were sent to the their deaths. He has been on trial for war crimes, crimes against humanity, trial and murder since March 30.

Long Panhavuth, a program officer of Justice Initiative in Cambodia, part of the Open Society Justice Initiative, said the court did not need to add evidence that could slow down the proceedings.