In a bland courtroom on the outskirts of Phnom Penh next week the justice that most Cambodians believed had passed them by will finally begin to creak into motion.

Three decades after the fall of Pol Pot, the first trial of the leaders of his genocidal Khmer Rouge regime is to begin before a UN-backed tribunal - the Extraordinary Chambers of the Courts of Cambodia (ECCC).

On Tuesday a thin, elderly former schoolmaster will stand in the dock accused of crimes against humanity committed 30 years ago.

Kang Kek Ieu, known as Comrade Duch, was the director of the infamous Tuol Sleng prison, the torture and interrogation centre in Phnom Penh where thousands of innocent people were sent to die.

His trial will be followed by those of Pol Pot's inner circle: Nuom Chea, or “Brother Number Two”, who was in charge of security; Ieng Sary, the former foreign minister and his wife Ieng Thirith, and Khieu Samphan, the former head of state.

The trials will be a watershed for Cambodians, most of whom had lost hope that the men and women who destroyed their lives would ever be brought to justice. “I never thought this day would come,” Vann Nath, one of only three remaining survivors of Tuol Sleng, told The Times. “There has been no hope for so many years.”

Robert Petit, the Extraordinary Chambers co-prosecutor, said: “There is a great need for justice in this country. Many Cambodians still don't understand why they were persecuted”.

The party leaders presided with Pol Pot over an ultra-Maoist regime whose four years in power turned a peaceful, sleepy Asian nation into a slave state. More than 1.7 million Cambodians, nearly a quarter of the population, died of starvation and disease or were executed for counter-revolutionary “crimes”.

Duch, who converted to Christianity in the 1990s, was arrested in 1999 after a journalist tracked him down in Thailand. Although Pol Pot died peacefully in 1998 after being sentenced to life imprisonment by a “people's tribunal” of his former colleagues, other senior cadres continued to live in comfort, many in Phnom Penh and on the Thai border.

Hope that they would be brought to justice was first raised in 1997 when the Cambodian Government and the UN began discussions on the creation of an international criminal court. But even after the creation of the ECCC - a hybrid Cambodian and international tribunal - in 2007, negotiations continued to be mired in political wrangling.

Time is of the essence. The leaders and their victims are elderly - Ieng Sary, the oldest, is 84 and Duch, the youngest, is 66. Many have health problems and there is no certainty that they will all survive until the final verdict, which may still be years away

IN THE DOCK

Nuon Chea, 82 “Brother No 2”. The most senior surviving member of the Khmer Rouge regime. Pol Pot's deputy for 30 years, he presided over the deaths of hundreds of thousands of people in Tuol Sleng and other security centres

Ieng Sary, 84 “Brother No 3”. Studied with Pol Pot in Paris. After the Khmer Rouge victory in 1975 he appealed to wealthy expatriates to return home, where they were executed or imprisoned

Ieng Thirith, 78 Ieng Sary's wife and Pol Pot's sister-in-law. As minister of social affairs she ordered widespread purges, including those of her own ministry staff

Khieu Samphan, 77 Head of state of the Democratic Republic for Kampuchea. Was a faithful follower of Pol Pot's agrarian ideal but claims he was never directly involved in the party's atrocities. He took over from Pol Pot as leader of the Khmer Rouge in 1985

Kang Kek Ieu (Duch), 66 Ruled over Tuol Sleng with brutal devotion; under his rule all but 14 of the 17,000 inmates died. Fled Phnom Penh when the Vietnamese invaded, but was arrested in 1999 .

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