Judges at the UN-backed Khmer Rouge tribunal halted proceedings in the trial of prison chief Duch Wednesday, after a clerk began reading documents with witness’ names that were supposed to be concealed.

The atrocity crimes trial for Duch, whose real name is Kaing Kek Iev, will resume next week, as court officials seek to protect the identities of witnesses that they fear could be compromised if their true identities were known.

Judge Nil Nonn, head of the tribunal’s Trial Chamber, said the names of the witnesses will have to be changed in documents before their testimony is read in court. He postponed proceedings until Aug. 3.

Tribunal spokesman Reach Sambath said Wednesday the court “respects the rights of the witnesses who do not want to be named in a public hearing.”

Some witnesses had asked that their identities be disguised, and the court would now “prepare all the records to hide the identities of the witnesses,” he said.

Kong Sam Onn, a lawyer for the defense unit, said witnesses could suffer from pressure outside the court if they are identified, potentially compromising their neutrality.

“The court stopped reading the record because it could affect the safety and security of the witnesses,” he said.