LOWELL -- In a dark movie theater, three generations searched for answers.
Why did nearly two million people have to die?
From 1975 to 1979, the Khmer Rouge regime under the notorious Pol Pot carried out mass genocide in Cambodia. Thirty-five years later, the real story behind the murders remained shrouded in secrecy.
Investigative journalist Thet Sambath -- whose mother, father and brother perished in the genocide -- spent the past 10 years digging for the truth. In his documentary, Enemies of the People, which he co-directed with Rob Lemkin, Sambath interviews everyone from foot soldiers who slit throats to Pot's second in command.
The film, which marks the first time a top Khmer Rouge leader has admitted to executing orders for killings, was the fifth-highest grossing movie at Showcase Cinema in Lowell over the weekend.
in a crowded theater Sunday night, there were moments when the Mom family held their breath as the untold story of their past played out in front of them. "It's unreal," said Chanvon Mom, 29. "I've lived in Lowell for over 28 years, and I've been coming to this movie theater since it's been here. I never thought I'd be able to sit here and watch my personal history come to life on screen like this.
"It's still very hard for my own family to share the details of what happened," she added. "There was so much death. This film shows us a side that we have never seen before."
There were only two men at the top of the Khmer Rouge: Pol Pot, who was called Brother No. 1, and Nuon Chea, Brother No. 2.
Since Pot's death on April 15, 1998, Sambath said only Chea can answer why the killing happened.
To get those answers, Sambath found the 82-year-old Chea living in a cabin deep in a forest. Now an old man with missing teeth, Chea refused to speak a word to Sambath for three years. Still, Sambath continued to visit the old man, working to earn his trust.
And after several years, Chea began to open up. Throughout the interviews, Sambath kept his own family tragedy a secret to avoid breaking Chea's trust.
"I think only a real killer can tell the truth," Sambath tells the camera.
The journalist also forges close relationships with ex-assassins, Khoun and Soun, who give chilling accounts of how they murdered thousands, piling bodies in ditches, rivers and ponds.
Talking to Sambath in the rural fields northwest of Cambodia, the two men point out exact places where the murders took place. Thousands of bodies decomposing in the river made the water look like it was boiling, one woman recalled.
In another scene, Soun demonstrates how he committed the murders by placing a plastic knife against the throat of an uncomfortable-looking subject. Soun said he did it so much his hand ached, so he switched to stabbing his victims in the neck.
Koun said the plan was to wipe out all ethnic minority people. He tells Sambath about children crying when they see their father being smashed into a ditch.
"Then we took the kids and killed them, too," he said.
Visiting the fields at night, when most of the executions happened, Soun admits to carrying around a human gallbladder that he drank from regularly.
Mom's sister, Chandavy, fidgeted in her seat during that moment. Chandavy Mom was about 13 when the genocide was taking place.
She remembered a man offering her a human liver to eat. She leaned over and told her sister about the terrifying moment.
Sambath's visits with Chea ultimately reveal a recorded confession.
"Criminals," Chea says, referring to the people who were murdered.
"If we let them live, the party would have been hijacked," Chea tells Sambath. "It was the correct solution. The country was in danger of being taken over by Vietnam."
But when asked about killing Cambodians, Chea tells Sambath that "it was USA and Vietnam, not Cambodia killing Cambodian people."
Mom's father, Chhann Mom, was 35 in 1975. He had to hide his identity from Khmer Rouge foot soldiers. He saw the bodies of the dead.
The eldest Mom said the most disturbing part of the film was hearing Chea put the blame on the United States and Vietnam.
"The entire movie was difficult to watch for me," Chhann said, his daughter, Chanvon, translating. "I consider myself to be very lucky because I did not lose any immediate family members. I am so sad for those families that have been torn apart by the Khmer Rouge."
He calls Sambath a "true hero for all people."
"This movie is a great starting point for the younger generation," he said. "I hope to see this movie used in the school systems, especially in communities with Cambodian people. Education is the key to rebuilding Cambodia."
Lemkin attended showings over the weekend at Lowell's Showcase Cinema to meet viewers and answer questions.
Out of hundreds of hours of video footage and more than a thousand hours of audio tapes, Lemkin said he and Sambath expect to create another documentary next year that delves more heavily into the politics that propelled the genocide.
Enemies of the People, now showing worldwide, has swept several awards, including the Sundance Film Festival's 2010 Special Jury Prize and the Human Rights Watch Nestor Almendros Award for courage in filmmaking.
"It's unbelievable that Sambath was able to gain this kind of insight to a very secret and dark time," Lemkin said. "Hopefully, it's opening a door and taking the Cambodian people to new places in their lives. It was very important to Sambath to help his country move forward."
The film will play at Showcase Cinema in Lowell until Nov. 23. For more information about the documentary, visit enemiesofthepeoplemovie.com.