Mr. Lim is a Cambodian refugee, high-school teacher, and volunteer at the Cambodian Association of Illinois. In 1975, he was driven out of his home at gunpoint, alongside the rest of the nation, and forced to work the land under a communist regime led by Pol Pot and Nuon Chea now called the Khmer Rouge.

New demographic studies released Wednesday by the Khmer Rouge tribunal—a UN-backed court now gearing up to try Nuon Chea for crimes against humanity and genocide of Cham Muslims and ethnic Vietnamese—suggests that the death toll under the communist regime is slightly higher than previous estimates. Between 1.75 and 2.2 million people perished between 1975 and 1979, the Phnom Penh Post reports. Of these, between 800,000 and 1.3 million were violent deaths.

Few answers to the obvious question—Why?—have ever been found. Still, a very smart reporter for the same paper mentioned above decided to ask it anyway. Thet Sambath’s unbelievable film, Enemies of the People, opens tonight at the Gene Siskel Film Center. In Nuon Chea’s own words, you’ll hear why, and how, his regime killed so many—approximately 18.7 percent of the ethnic Khmers living in Cambodia between 1975 and 1979.

But as Mr. Lim explains, this was by no means the only damage the regime inflicted on the country. Nor were the Khmer Rouge the only ones making what life remained quite difficult for survivors.

I joined millions of them to leave home to the labor camp. And I tell you that I witnessed, umm … children, elderly people, patients driven from their beds in the hospital, physically disabled people, abandoned along the way. At that time, a family had no time to properly bury the lost ones. So they basically, they just did the best they could. Cover the body and let them behind.

By the time you reached labor camp, you were exhausted already. And you were forced to work in the labor camp. I worked for—and everybody else, too—from 5, 6, 7 in the morning until 7, 8 o’clock at night, sometimes until 9 o’clock at night, and you were given only handfuls of rice to eat. Per day.

I was extremely exhausted. I was hungry all the time, and this was going on for almost four years. There was no medical care available whatsoever. I witnessed also people that died from hardship, from starvation, malnutrition, disease, execution. I saw them all. Including myself, that I experienced the hardship with the disease and those kinds of things. Except I was one of the lucky ones. I was not executed. I survived.

Vietnam invaded Cambodia in late December 1978 and early January 1979. During that time was a chaos, another chaos in the country, because of another war. During that time, you had a chance to move around in the country. During the Khmer Rouge regime, you couldn’t travel, you could travel only from one village to another, but you needed permission to do that. But during the Vietnamese invasion, you had the chance to come back to your hometown if you wanted to, especially the area that I lived in, which was Kampong Thom. It’s in the near northeastern zone of the country, right near the border of Cambodia and Thailand. A very remote area.

I came back to my hometown. It took me almost two weeks to reach my hometown. And then I found out that all my parents, my siblings, my family—were all executed. There was nobody left except three that lived in Phnom Penh that survived during the labor camp.

So we came back to our hometown, and I decided that I could not live with another form of communist type of government. I see no future whatsoever, a lot of uncertainty. A country with no rule or law. So I determined to leave the country, whether I survived or not, I was determined to leave. Six months after I arrived, I decided to escape Cambodia.

That’s what I did. I left Cambodia, I left my hometown and walked along the road and through the jungle to reach the Cambodian-Thai border. It took almost two weeks to reach the border because you could not walk fast. Because you don’t want to make yourself more visible to the Vietnamese soldier, to the government during that time, the regime during that time. You don’t want them to know that you’re escaping the country. During that time, the Vietnamese were in power. The Khmer Rouge had been pushed out to the jungle.

You try to blend yourself to the rest of the population, just move from one place to another without letting anybody know. You could not carry a lot of things, either. You have to travel on the road and off the road, at night, find a safe place to hide, under bushes or somewhere off the road, but not too far off the road because there’s a lot of mines out there. So do the best you can. At night, find bushes to hide underneath, and early in the morning continue your journey to the border. If you’re lucky, you have no people rob you or do anything to harm you. I survived.

At that time, I came with a few members of the family. I actually married before I left, so I came with my wife and a member of her family. So I reached the border and during that time the UNHCR [United Nations High Commissioner for Refugees] opened the Khao-I-Dang refugee camp on Thai soil, so the bus picked up the refugees from the Cambodian side and transported them to Khao-I-Dang, the Thailand side.