The Documentation Center has provided around 500,000 documents to the tribunal since its inception.
Meanwhile, the US is making diplomatic efforts to improve its relationship in Cambodia.
Thirty-eight people remain in unlawful detention after they were seized by authorities as they protested outside City Hall this week.
Hor Namhong told reporters Thursday that Asean leaders could help ministers of North and South Korea meet on the sidelines.
Jailed Khmer Rouge leader Khieu Samphan refused to answer questions from the UN-backed tribunal on Thursday.
The demonstrators were seized Wednesday, where they had demanded the courts release eight representatives arrested earlier this month.
Around 300 families lost their homes in the Jan. 3 forced eviction of Borei Keila.
An estimated 20,000 Cambodians are trafficked throughout the region each year.
A UN spokesman said the organization was “aware of this development” but declined to comment further.
A US Embassy spokesman confirmed Baer had met with government and opposition officials, but declined to elaborate.
Nuon Chea’s portion of the hearing lasted just a half a day Tuesday.
Cambodia and other Asean countries have adopted a draft of a charter for human rights that will see rigorous debate next month.