Those arrested were Khat Sovann, 54, Pum Vannak, 53, Pon Soeurn, 34, and an unnamed fourth suspect.
Rights workers estimated between 400 and 1,000 villagers in Broma village, Chlong district, were set to be evicted.
At least 10 parties have registered for elections, which will be held across 1,633 communes next month.
Family members say Chan Samnang died because of exposure to poor living conditions at a relocation site outside the city.
An attorney for the three women, called the summons “a good opportunity” that would allow the women to “tell the true story."
Villagers say they have been pushed off nearly 1,500 hectares of land to make way for the senator’s sugar cane crops.
The study interviewed 1,522 people in Phnom Penh and the provinces of Kampong Speu, Prey Veng and Takeo.
Joel Brinkley, a professor of journalism, spoke to VOA Khmer recently about his book and possible solutions to Cambodia’s “curse.”
An estimated 2.3 million hectares were given over as concessions to private companies in recent years, Adhoc recently reported.
The 27-minute film follows the work of a leading NGO working to rally support for an end to widespread land grabbing in Cambodia.
A United Nations-appointed rights watchdog is calling on Cambodia to bridge the widening gap between the rich and the poor.
A Cambodian-American group in the US has begun lobbying Washington institutions in an effort to affect political change in Cambodia.