SAN JOSE, CALIF. - Sophany Bay's three young children died in her arms, one after the other, during Cambodia's genocide.

Sarem Neou lost her two daughters to starvation and disease; her mother was dragged to death by a horse after she was suspected of stealing food for one of the girls, and her husband died after learning of the horrific deaths of his children.

Kelvin So's brother, a surgeon, was one of thousands of professionals executed by Khmer Rouge soldiers.

Collectively, the three survivors lost hundreds of relatives -- aunts, uncles, cousins, nieces, nephews -- during the reign of terror from 1975 to 1979 in Cambodia when an estimated 1.7 million people died, about a quarter of the small Southeast Asian country's population.

Now Bay, So and Neou are among 45 Cambodian-Americans getting the opportunity to see justice done. When opening arguments started Monday in Phnom Penh in a trial of former Khmer Rouge leaders charged with crimes against humanity, Bay and Neou were sitting in the gallery alongside other witnesses to genocide. They and the other Cambodian-Americans are being legally represented in the trial. "I want to see justice before I die," said Bay, 66, a San Jose mental health counselor. "I want to see those killers and ask them, 'Why? Why did they kill so many people? Who stood behind the killing fields?' Before I die, I want justice."

The United Nations-backed tribunal, the second prosecution of Khmer Rouge leaders, is simultaneously a criminal and civil proceeding that could last more than two years. Its mandate is to try leaders responsible for the killing of hundreds of thousands of Cambodians. Civil claimants seek reparations, perhaps a permanent memorial in Cambodia, and the chance to face those who unleashed ineffable brutality on their lives.

The defendants are Ieng Sary, who was foreign minister; Khieu Samphan, a former head of state; and Nuon Chea. A fourth defendant, Ieng Thirith, has dementia and last week was declared unfit to be tried and ordered freed from detention. The regime's top leader, Pol Pot, died in 1998. In the first trial, Kaing Guek Eav was sentenced to 19 years in prison for the torture and death of at least 14,000 people.

The Khmer Rouge took control in 1975 after the war in next-door Vietnam spread to Cambodia. Khmer Rouge leaders evacuated cities and banned modern technology to create an agrarian culture to purify the nation as a foundation for a new Communist society. This included killing countless Cambodians, particularly the educated.

Neou was in Paris on a scholarship when Pol Pot took over the country April 17, 1975, but returned because she was unable to bear the thought of her children and husband facing these horrors while she was safe. She was placed in a work camp.

Those who survived did so because of luck, cunning, faith and a fierce drive to live, the survivors say. "I don't know if I am strong or weak," said Neou, 71. "But I have a willpower."

So, whose position as a police inspector should have led to his quick execution, was beaten with an ax handle during an interrogation. He finally confessed to being a police inspector, but used a formal term not understood by the soldiers, who most likely were illiterate. It saved his life.

Bay's husband, Sarit Bay, a military officer, was being trained in the United States when the Khmer Rouge charged through Phnom Penh, ordering everyone to the countryside. Sophany Bay left with her three young children and few supplies.

With little food and no shelter, her infant daughter fell severely ill. One day Bay carried her 5 miles to an infirmary, where a soldier injected a lethal substance into the baby's head.

"Instead of saving her, he killed her," she recalled, her body shaking at the memory.

Bay's other two children were interrogated and beaten by soldiers seeking the identity of their father. The boy, 6, died silently in her arms one night, while her 5-year-old daughter "talked until the last minute," Bay said. "They killed my whole family," she said. "Nobody is alive, only me and my husband."

Neou, who now lives in Silver Spring, Md., didn't learn about the death of her family until after Vietnamese soldiers invaded Cambodia, ending the reign of the Khmer Rouge.

Even though they were deposed by Vietnamese forces in 1979, Khmer Rouge leaders remained free from prosecution for decades. Wrangling between the tribunal and the Cambodian government, which includes former members of the Khmer Rouge, has dampened enthusiasm for the trial. Prime Minister Hun Sen was a low-ranking Khmer Rouge member before joining the government created by Vietnam while Cambodia was under Vietnamese military occupation.

The international prosecutor for the tribunal wants to bring at least two more cases against former leaders of the regime, but the Cambodian government, which has been accused of tampering with the process, has resisted. Observers say the government fears current political leaders could be affected.