Around 2,120 victims who have registered as civil party complainants have been accepted from more than 4,000 applications.
Under the Pol Pot regime, people were taught to keep silent, and often their survival depended on that silence.
Hun Hean was removed from his post following the January 7 holiday celebrations.
Jan. 7 remains a contentious day for Cambodians, marking both the ouster of the Khmer Rouge and the beginning of Vietnamese occupation.
Hun Hean, the recently demoted police chief of Banteay Meanchey province is being held on suspicion of drug trafficking.
Critics say the proposed law creates tangles of red tape that could be used to attack groups that don't follow the government line.
Relatives of the defendants, reporters and Thai Embassy officials were barred from the courtroom in Phnom Penh on Thursday.
More than 700 people sought the free services of the doctors and medical staff on the first day, Monday.
Professor Sum Chhum Bun says the literature, arts and culture during the regime were used for Marxist-Leninist ideology.
Cambodia has a total nine mobile operators for its 6.3 million users.
The seven suspects, including a Thai member of parliament, were detained last week for allegedly crossing the border illegally.