The UN-backed Extraordinary Chambers in the Courts of Cambodia (ECCC) commenced appeal hearings for two former Khmer Rouge leaders on July 2 who were accused of crimes against humanity last year.
Nuon Chea, 88, and Khieu Samphan, 83, were among the first top leaders of the regime responsible for the deaths of up to two million Cambodians from 1975-1979 to be jailed.
The court will hear from three new witnesses by the request of defence counsels.
As scheduled, there are two hearing sessions this week and two others next week.
The ECCC is expected to make appeal judgements in the first quarter of 2016.