Khmer Rouge tribunal judges outlined some of the progress they’ve made in investigating the second case against jailed leaders of the regime, urging victims to continue to file as witnesses and complainants.

The investigation has covered 16 provinces, as well as the capital, and will group the five jailed leaders together, including Kaing Kek Iev, or Duch, who has been undergoing a separate trial for his role as chief of Tuol Sleng prison.

Nuon Chea, Khieu Samphan, Ieng Sary and Ieng Thirith are also being investigated under Case No. 002.

Tribunal officials said Thursday the investigation had found instances of forced labor in six provinces, as well as 13 detention centers and execution sites in 10 provinces. Investigators are also looking into forced evictions and marriages and crimes against ethnic minorities, Muslims and Vietnamese.

Thursday’s discussion was the first unveiling of the tribunal’s investigatory workings, and tribunal officials encouraged more people to file with the Victims Unit of the UN-backed court, to help further.

“If they want to become a civil party, they need to apply as soon as possible,” said Lars Olsen, a spokesman for the UN side of the court.

Helen Jarvis, head of the Victims Unit, said the tribunal has received more than 5,000 complaints from victims in cases No. 001 and No. 002. Around 1,482 have filed complaints as victims for the upcoming case.