Khieu, now 41, has a hard time talking about his role in one of the worst genocides in human history. Standing in a paddy field near his home in Kampong Tralach, two hours north of Phnom Penh, the wiry farmer vividly recalls his conflicted feelings as a child soldier: the thrill of joining the Khmer Rouge, the fear of offending his ruthless commanders, the shock of returning to a ravaged home. But when the conversation turns to S-21–the nerve center of the Khmer Rouge killing machine–Khieu’s mind goes fuzzy and his voice rises in agitation. “If I didn’t obey orders, I would’ve been killed!” he says. “I didn’t know anything, OK? I was just a child.” His pleas of innocence are understandable. Of the 14,000 men, women and children imprisoned at S-21, only seven survived–including one who would return, 24 years later, to haunt Khieu’s memory.

Like Khieu, Cambodia has never really come to terms with its traumatic past. During Pol Pot’s four-year reign of terror, an estimated 1.7 million people died–one fifth of the country’s population. More than a million fell victim to disease, starvation and forced labor. The rest, starting with those who wore glasses (the educated classes), were executed in cold blood. Pol Pot and his henchmen, the same men who may soon face trial for their actions, ordered the country to return to the blankness of “Year Zero.” But the executioners themselves were often uneducated child soldiers who were conditioned to commit acts of unspeakable cruelty. Were they perpetrators or victims, too? Today several hundred thousand of these former cadres–now in their late 30s and early 40s–live in villages across Cambodia, among people who could easily have been their victims. They are powerful metaphors for their country. In them, the threads of guilt, denial, horror and memory are hard to disentangle.

How does a society move toward the future when the past is such a heavy burden? More than two decades after the Cambodian genocide, none of the Khmer Rouge leaders has been brought to justice. But next week, King Norodom Sihanouk is expected to approve a tribunal to try “those most responsible” for the killing. Like the ongoing prosecution of war crimes in Rwanda and Yugoslavia, a Khmer Rouge trial could be a crucial step toward healing a traumatized country.

But the road ahead is treacherous. The tribunal, to be jointly run by local and international judges, will be held on Cambodian soil, where the Khmer Rouge, though spent as a military force, still looms large in government and in daily life. And that raises more questions: How will a trial deal with the past without unleashing new demons? How will it balance the desire for justice and the need to preserve peace? And how will Cambodia handle the deeper issues affecting every village, where victims and perpetrators still live side by side?

More than two decades later, Cambodians remain deeply ambivalent about bringing Khmer Rouge leaders to trial. It’s not that they’re suffering from amnesia; beneath the surface, nearly every family has searing memories of life–and death–under Pol Pot. Nor is it simply that Buddhism, the religion practiced by most Cambodians, does not revolve around concepts such as confession, forgiveness and retribution. The main reason: Cambodians worry that a tribunal might endanger the only period of peace and stability they have had in 30 years. With the death of Pol Pot in 1998 and the surrender of other top commanders, there is little threat of a renewed civil war. But Cambodians still fear selective terror and a spiral of vengeance. “Witnesses may be safe in front of all the cameras in Phnom Penh,” says opposition leader Sam Rainsy. “But what happens back in their village in the middle of the night?”

Such fears are only exacerbated by widespread doubts about the government’s commitment to a rigorous trial. Prime Minister Hun Sen is a former Khmer Rouge member, as are many in his administration, and he has cut deals with several aging Khmer Rouge leaders in exchange for their surrender. A few years ago Hun Sen advised Cambodians to “dig a hole and bury the past.” Now, after receiving $600 million in aid pledges in June from foreign governments that strongly support a tribunal, he favors a trial. But he insists that the United Nations cannot dictate its terms. “I’m displeased with the way they are working,” he told NEWSWEEK in an interview. “They are a god without morals”.

The Khmer Rouge, of course, were the ones who twisted morality to their own maniacal ends. In their attempt to build a new communist society, they recruited and indoctrinated hundreds of thousands of rural youth to serve as their revolutionary vanguard.

There are no easy answers, especially when the worst atrocities were carried out, in effect, by mere children. Were these boys and girls perpetrators or victims, too? The Khmer Rouge recruited hundreds of thousands of rural youth to serve as its revolutionary vanguard. When Khieu joined the movement in 1975, he was the ideal tabula rasa on which to write a revolution: he was young (15), illiterate and filled with anti-imperialist hatred. Back home in Kampong Tralach, Khieu guides a visitor across the rice fields to a crater, 30 meters in diameter, now covered in lotus pads. “This was caused by an American bomb,” Khieu says, explaining why the Khmer Rouge had allure for him and other rural kids to explain why he was drawn to the Khmer Rouge. “A lot of peasants around here got killed by the American imperialists.”

At first, Khieu and his friends were proud to join the Khmer Rouge. The training was grueling, and they missed their families. But when they rode on a military truck to the capital–for many, it was their first ride in a motor vehicle–the kids felt almost omnipotent in their black uniforms, rubber sandals and red-checked scarves. They sang, laughed and told stories, unaware that they were being taken to the heart of darkness. “We were young,” says Phlong Kheng, a former S-21 cadre from Baribo province who joined the Khmer Rouge at 13. “We didn’t know how to be afraid.”

They learned about fear in S-21. The Khmer Rouge had 169 prisons around Cambodia that were equally brutal, but S-21 was the center of its security and intelligence operations. Its director, a former schoolteacher named Kang Kech Ieu, a.k.a. Duch, kept fastidious records of every prisoner and comrade and ran the place with murderous efficiency. The young cadres knew their survival depended on absolute obedience to Duch and “the Organization.” Any violation of his strict rules–no talking, sitting, sleeping or smiling on the job–could result in imprisonment, even death.

Nobody, however, was ever punished for treating prisoners too cruelly. Hundreds, sometimes thousands, of starving prisoners were jammed into the four main buildings at S-21. None of the former cadres NEWSWEEK interviewed would admit they were involved in torture or killing. But Kheng, a guard assigned to Building C, can’t forget the screams of torture victims at night. Cheam Soeu, a perimeter guard who joined the Khmer Rouge at the age of 12, remembers seeing two Caucasian prisoners being burned alive. Khieu, for his part, insists he was not a killer, but he says “sometimes I beat prisoners who didn’t follow my orders.”

Khieu feared for his own life, though, when the revolution began devouring its children. In a frenzied purge of Khmer Rouge cadres three years after he joined, dozens of his S-21 comrades were imprisoned, tortured and executed. “The more you knew, the more you were in danger,” says Khieu. He says he came under suspicion when a friend named Heng was interrogated and killed. “When the commander came into my room, I was so afraid that I didn’t even dare to look at him in the face,” he says. “If you did something wrong, they wouldn’t just kill you. They’d kill four or five of your friends and relatives, too.” Khieu survived. But when he returned home after the Vietnamese invasion in January 1979, his words seemed like prophecy: the Khmer Rouge had killed four members of his family. “I joined [the Khmer Rouge] to help my country, but they destroyed my family,” he says.

Khieu’s loss, ironically, helped him win a measure of peace. His neighbors, all of whom suffered under the Khmer Rouge, know about his past at S-21. But they haven’t confronted him, either because they prefer not to remember or because they see him as something of a victim, too. Over the years, Khieu has built a life on the rice fields, marrying a local girl, raising five children and slowly regaining the villagers’ trust. He is now the development chief of his small commune, overseeing the construction of a dirt road across the paddies. But the serenity is deceptive. Khieu still seeks out the company of his former comrades, including Cheam Soeu, who lives nearby. Sitting near his thatch-roofed home, Khieu is edgy and evasive, his voice stuttering like a machine gun as he protests his innocence. It is midmorning, but his eyes are glassy from a bout of drinking. When asked if he’s haunted by memories of S-21, Khieu abruptly stands up and walks away. “I’ve answered enough questions,” he says.

The past, when it is horrible beyond comprehension, can be easier to forget than to remember. Some former child soldiers are willing to talk, even if only obliquely, about their experience in the Khmer Rouge. But for many, the past is as concealed and dangerous as the unexploded land mines in their fields. (Rank-and-file revolutionaries have a harder time than Khmer Rouge leaders, many of whom cut deals with the government or became gem and timber traders in the rebel-run frontier town of Pailin.) Earlier this year a researcher trying to contact one former cadre showed neighbors the man’s 1977 mug shot from S-21. Word flashed through the village that a former S-21 torturer lived in their midst. The angry villagers marched on the former cadre’s home, harassing and threatening him as he cowered in his hut. Cambodia has never fully faced its past in part because of this–the danger of pitting neighbor against neighbor.

For all their fear of chaos, most Cambodians still see the need to have a reckoning with the past. The shadow of genocide still hangs over Cambodia, from the widespread culture of impunity to the motocab drivers tempting tourists with a ride to the “Kee-leen Feel.” The tribunal is meant to be the first step toward healing the wounds of the past. But how far will it go? Proceedings will most likely focus on six or seven high-level Khmer Rouge leaders, including Duch, a born-again Christian who has already confessed to crimes he committed at S-21. The big question will be whether Ieng Sary, Pol Pot’s foreign minister, will be forced to stand trial. A key architect of Khmer Rouge policy, he was granted an amnesty by King Sihanouk after surrendering to Hun Sen. If ordered to arrest Ieng Sary, will Hun Sen oblige?

Khieu Ches at least can breathe easily. The one thing everybody agrees on–including Hun Sen and the United Nations–is that the trial will not drag in lower-level cadres who carried out their commanders’ orders. “We are living and working among our killers. What do we do?” says human-rights worker Kassie Neou, who spent six months in a Khmer Rouge prison. “Can we put the whole country on trial? No, that’s impossible. We have to find a way to live together. We have no choice.”

Nobody believes the tribunals will be perfect. Even if the United Nations participates–negotiations should conclude later this month–there will be the question of how the three Cambodian judges and two international judges can agree on international law. (Cambodia’s judiciary was so decimated by the Khmer Rouge that even today only 21 of Cambodia’s 170 judges have finished law school.) The important thing, says Cambodia’s top genocide researcher, is to begin the process. “This may be our last chance to judge the [aging] leaders of the Khmer Rouge,” says Youk Chhang, the director of the Documentation Center of Cambodia, which will provide documents to both the prosecution and the defense teams. Every step, he says, will help bring closure to the victims and contest the argument that might makes right in Cambodia. “We are a shattered country,” he says. “We must rebuild by putting it back together piece by piece, person by person.”

Vann Nath has his own black-and-white mug shot from S-21. He wasn’t a Khmer Rouge guard, however; he was one of the shackled prisoners in the third-floor classroom of Building D. One of the seven survivors from S-21, Vann Nath remembers Khieu Ches as a young guard who ruled supremely over the antechamber of death. Khieu was 16; he was 32. Vann Nath, a painter by profession, arrived at S-21 in January 1978 from Battambang, where he was detained for a week and tortured for phantom crimes that neither he nor his interrogator could identify. On Khieu’s watch, Vann Nath was stalked by starvation and a sense of powerlessness. Khieu says he was a “servant of the prisoners,” giving them food, water and showers. But Vann Nath only remembers being shackled by leg irons in a prone position and eating so little–two bowls of gruel a day –that he craved the insects crawling on the ceiling above.

Vann Nath’s life was saved by a stroke of luck. About a month after his arrival, Duch, the S-21 director, recruited him to paint heroic portraits of a jowly, smooth-skinned man he later learned was Pol Pot. “If I didn’t know how to paint, I would not be talking to you today,” says Vann Nath, sitting in his home in Phnom Penh. “I would be just another skull in the Killing Fields.” Not long after Pol Pot fell, Vann Nath found a document in the S-21 archives ordering that his fellow prisoners in Building D–the ones under Khieu’s control–be taken away and killed on Feb. 16, 1978, just days after he began painting.

Since emerging from S-21, Vann Nath has tried to honor the dead by forcing himself–and Cambodia–to look hard at the past. He has strived to live a normal life, raising three children, running a restaurant, painting in his open-air studio upstairs. But the memories never loosened their grip. “I tried to forget, but I can’t,” he says. Now 56 years old, with a shock of white hair over his broad features, he strolls through the tranquil grounds of S-21, preserved as the Tuol Sleng Museum of Genocidal Crimes. The walls are covered with thousands of black-and-white photos of prisoners, their eyes staring accusingly back at the visitor. Vann Nath’s own paintings, hung in Building D, depict the gruesome forms of torture practiced at S-21. As he talks to a friend, three schoolgirls in white blouses and blue pinafores skip into the room. They stop to stare at a painting of a child being ripped from her mother’s arms. “There is a danger the young generation will forget,” says Vann Nath. “That’s why I painted these: so history wouldn’t repeat itself.”

The first time Vann Nath bumped into one of his former tormentors, he shook with fear and rage. One of his former guards had come back with friends to take a look at S-21, covering his face with a scarf. Vann Nath pulled the former guard into a room and threatened to kill him. “But I let him go,” he recalls. “I wanted to show him that I was not like him, that I wouldn’t kill for no reason.” Over the years, Vann Nath’s desire for vengeance has transmuted into a simple, aching need to understand the horror. The images of torture in his painting have disappeared, replaced by more bucolic scenes–a fisherman casting his net on a glistening river, buffalo carts moving down a rural road.

But the only way Vann Nath can get to those places in his own mind is by facing down his past. Unlike most Cambodians, he has made a point of tracking down his former tormentors–not to carry out a vendetta or hold a tribunal, but to have a face-to-face talk. When Vann Nath heard, earlier this year, that researchers had located Khieu, he arranged a visit to Kampong Tralach.

Khieu welcomed the former prisoner to his home among the paddies. But he didn’t apologize for his actions in S-21. He even tried to argue that he, too, was a victim of the Khmer Rouge. Vann Nath quietly objected. “They say they are victims, but I saw them,” he said later. “They liked torturing prisoners. They did it willingly.” Still, he and Khieu realized that, in many ways, they were not so different. Neither of them had much control over the events that scarred their lives. And here they were, two grown men sitting down together on the dirt and talking, civilly, about a horror neither they nor Cambodia can forget.