AKA 'Brother Number One'. Birth name Saloth Sar.

Country: Cambodia.

Kill tally: One to three million (or between a quarter and a third of the country's population).

Background: Cambodia becomes a French protectorate in 1863. Complete independence is finally granted in November 1953, with Prince Norodom Sihanouk establishing a 16-year rule. The region is soon destabilised by the war in Vietnam. In November 1963 Sihanouk terminates an aid program run by the United States and in May 1965, as the war spills into Cambodia, breaks relations completely.

Meanwhile, domestic opposition to Sihanouk begins to mount. A ruthless clampdown on opponents forces many to go underground and take up arms, including the Khmer Rouge, the Cambodian communist insurgency movement led by Saloth Sar, later to be known across the world as Pol Pot.

The threat of the communist insurgents, the effects of the lack of US aid, an increase in incursions by the North Vietnamese and Viet Cong and the subsequent counterstrikes by US and South Vietnamese forces lead Sihanouk to reevaluate the country's relations with Washington. But by the time he turns back to the US in June 1969 it is too late. More background.

Mini biography: Born on 19 May 1925 in Prek Sbauv in Kampong Thum province, north of Phnom Penh. His father is a prosperous farmer and his family has connections to the Cambodian royal family.

1931 - At the age of six he moves to Phnom Penh to live with his brother, an official at the royal palace. He learns the rudiments of Buddhism during a brief stay at a pagoda near the royal palace before receiving his formal education at a number of French language schools and at a Catholic college, although he never obtains a high school diploma.

1946 - While serving with the anti-French resistance under Vietnam's Ho Chi Minh, he joins the outlawed Indochinese Communist Party.

1949 - Pol Pot wins a government scholarship to study radio electronics in Paris. He fails to obtain a degree but becomes enthralled by writings on Marxism and revolutionary socialism and forges bonds with other likeminded young Cambodians studying in the metropolis, including Ieng Sary, Khieu Samphan, Khieu Ponnary, Khieu Thirith and Song Sen. The members of this so-called 'Paris student group' are destined to become the leaders of the Khmer Rouge.

While in Paris Pol Pot also joins the French Communist Party and helps transform the Association of Khmer Students into a platform for nationalist and leftist ideas, openly challenging the Sihanouk government.

In a pamphlet titles 'Monarchy or Democracy' he writes, "(The monarchy) is a vile pustule living on the blood and sweat of the peasants. Only the National Assembly and democratic rights give the Cambodian people some breathing space. ... The democracy which will replace the monarchy is a matchless institution, pure as a diamond."

1951 - The Indochinese Communist Party, which is dominated by the Vietnamese, is reorganised in September into three separate units representing Vietnam, Cambodia and Laos, although the Vietnamese continue to supervise the smaller movements. The Cambodian unit is named the Kampuchean People's Revolutionary Party (KPRP).

1953 - After having his scholarship revoked Pol Pot returns to Cambodia and throws himself into work for the KPRP, first in the Kampong Cham province northwest of Phnom Penh and then in the capital itself. He also travels to the east of the country to meet with the Vietnamese communists.

He supports himself by teaching history and geography at a private school, where he is well liked and respected by his pupils.

1956 - Pol Pot marries Khieu Ponnary.

1960 - In late September Pol Pot and the 'Paris student group' take control of the KPRP, renaming it the Workers' Party of Kampuchea (WPK) and turning it away from its Vietnamese patrons. Pol Pot is elected to the number three position on the party's Central Committee, allowing him to build a strong faction.

1963 - In February Pol Pot is chosen as the WPK's general secretary, the highest position in the party, following the mysterious disappearance of the previous incumbent. In July he and most of the WPK Central Committee leave Phnom Penh to organise an insurgency base, 'Office 100', on the border with Vietnam in the country's northeast.

1965 - Pol Pot walks the recently completed 'Ho Chi Minh Trail' to Hanoi, the capital of North Vietnam, for consultations with the North Vietnamese communists, who are critical of his nationalist agenda and tell him to delay an armed struggle in Cambodia until the US is driven from Vietnam.

1966 - He receives a better reception when he makes his first visit to China, where the 'Cultural Revolution' has just been launched. He is influenced by the leading radicals supporting the movement and by Mao Tse-Tung's concept of a continuous revolution. He will return to Cambodia determined to further loosen ties with the Vietnamese communists.

The WPK changes its name again, to the Kampuchean Communist Party (KCP), though the Cambodian communists are now more commonly known as the 'Khmer Rouge'. The party's all-powerful Central Committee, headed by Pol Pot, is referred to as 'Angkar' (organisation).

1967 - Returning from a trip to North Vietnam, Pol Pot takes refuge in the northeast of Cambodia. He lives with a hill tribe and is impressed by their simple, non-material way of life, seeing it as a realisation of communist ideals.

Insurrection breaks out in the west of Cambodia at the start of the year. It is suppressed brutally but not completely and spreads. By the end of 1968 unrest is reported in 11 of the country's 18 provinces and by the end of the decade the Khmer Rouge almost completely control the mountainous regions on the border with Vietnam.

1968 - The Khmer Rouge establish the Revolutionary Army of Kampuchea in January. Aided by the US, the army launches a small and ineffectual insurgency campaign.

1969 - In March the US begins secret bombing raids on Vietnamese communist sanctuaries and supply routes inside Cambodia (dubbed the 'Menu Series'). Authorised by the newly installed US President, Richard M. Nixon, and directed by his national security adviser, Henry Kissinger, the raids are illegal, as the US has not officially declared war on Cambodia. In 14 months, 110,000 tons of bombs are dropped. When news of the raids is leaked Kissinger orders surveillance and phone tapping of suspects to uncover the source.

US bombing raids into Cambodia will continue until 1973. All told 539,129 tons of ordnance will be dropped on the country, much of it in indiscriminate B-52 carpet-bombing raids. The tonnage is about three and a half times more than that (153,000 tons) dropped on Japan during the Second World War.

Up to 600,000 Cambodians die but the raids are militarily ineffective. The Central Intelligence Agency (CIA) reports that the bombing raids are serving to increase the popularity of the Khmer Rouge among the affected Cambodian population.

1970 - Sihanouk travels abroad in January to solicit Chinese and Soviet assistance to stop North Vietnam from encroaching on Cambodian territory during the course of its war with South Vietnam and the US.

On 18 March Sihanouk's right-wing opponents within the government seize the opportunity, banning his return from China and installing Defence Minister Lon Nol as premier of the newly proclaimed Khmer Republic. The coup is supported by the CIA.

The new, US-backed government stirs anti-Vietnamese sentiment and initiates ineffectual military operations against the Viet Cong troops. Simultaneously, the Lon Nol government cancels an agreement allowing North Vietnam to use the port at Sihanoukville.

In April US President Nixon authorises the invasion of Cambodia by a joint US-South Vietnamese force of 30,000 troops. Tasked with destroying Vietnamese communist bases inside Cambodia, the force pushes the Vietnamese further into Cambodia but is otherwise ineffective and is forced to withdraw in June by the US Congress.

In China, Sihanouk forms a government in exile and builds an alliance with the Khmer Rouge. Both are intent on seeing the overthrow of the Lon Nol government.

The Khmer Rouge receive military aid and training from the North Vietnamese and support from China and are quickly transformed into an effective fighting force, expanding from a small guerilla outfit of less than 5,000 to an army of 100,000 in a matter of months.

By June the republic's troops have been swept from the entire northeastern third of the country. Areas in the south and southwestern parts of the country are also overrun. By 1973 the Khmer Rouge are able to launch independent and successful attacks against the Khmer Republic troops, taking control of nearly 60% of Cambodia's territory and 25% of its population.

1973 - In an attempt to prop-up the Lon Nol government, halt the Khmer Rouge assault and destroy North Vietnamese bases in Cambodia, the Nixon administration secretly intensifies the bombing of the country, without government authorisation, and despite having signed a peace agreement with the North Vietnamese on 27 January.

1974 - In March the Khmer Rouge capture the old capital of Odongk, north of Phnom Penh. In a foretaste of what is to come, the city is destroyed, its 20,000 inhabitants are dispersed into the countryside, and teachers and public servants are executed.

1975 - Now in control of most the Cambodian countryside, the Khmer Rouge surround and isolate the capital Phnom Penh, which has swollen with refugees fleeing the Khmer Rouge and the US bombers. The noose steadily tightens. On April 17, Phnom Penh falls. Within days the city's entire population of over two million is marched into the countryside at gunpoint.

Pol Pot declares 'Year Zero' and directs a ruthless program to "purify" Cambodian society of capitalism, Western culture, religion and all foreign influences in favour of an isolated and totally self-sufficient Maoist agrarian state. No opposition is tolerated.

Foreigners are expelled, embassies closed, and the currency abolished. Markets, schools, newspapers, religious practices and private property are outlawed.

Members of the Lon Nol government, public servants, police, military officers, teachers, ethnic Vietnamese, Christian clergy, Muslim leaders, members of the Cham Muslim minority, members of the middle-class and the educated are identified and executed.

Towns and cities are emptied and their former inhabitants are deemed "April 17th people" or "new people." The country's entire population is forced to relocate to agricultural collectives, the so-called "killing fields." Inmates exist in primitive conditions. Families are separated. Buddhist monks are defrocked and forced into labour brigades. Former city residents are subjected to unending political indoctrination. Children are encouraged to spy on adults.

An estimated 1.5 million are worked or starved to death, die of disease or exposure, or are summarily executed for infringements of camp discipline. Infringements punishable by death include not working hard enough, complaining about living conditions, collecting or stealing food for personal consumption, wearing jewellery, engaging in sexual relations, grieving over the loss of relatives or friends and expressing religious sentiments.

Khmer Rouge records from the Tuol Sleng interrogation and detention centre in Phnom Penh (also known as S-21) show that 14,499 "antiparty elements", including men women and children, are tortured and executed from 1975 to the first six months of 1978. Only seven of those detained at the centre will leave it alive.

At least 20 other similar centres operate throughout the country.

Terror and paranoia reign, reaching a climax in 1977 and 1978 when Pol Pot launches a bloody purge against the "hidden enemies, burrowing from within" and the Khmer Rouge cadres turn on themselves. At least 200,000 are executed.

1976 - The Khmer Rouge declare the new state of Democratic Kampuchea on 5 January. Sihanouk resigns as head of state on 2 April and is placed under virtual house arrest in Phnom Penh. Pol Pot is made prime minister, although his identity and the identities of other members of the 'Angkar' group are kept secret from non-members. To most inside and out of Cambodia he is a shadowy figure known as 'Brother Number One'. The subordinate leaders of the party are known as 'Brother Number Two', 'Brother Number Three', and so on.

It is not revealed that 'Angkar' is in fact the Kampuchean Communist Party until September 1977.

A four year plan is introduced that seeks to treble the country's agricultural output within a year.

1977 - Although almost the entire population is involved in agricultural production, Cambodia experiences food shortages, resulting in many more deaths. Conflicts along the Thai, Laotian and Vietnamese borders escalate. Relations with Vietnam are broken in December. At the same time, Vietnam begins to turn away from China towards the Soviet Union.

Pol Pot, meanwhile, makes a state visit to China, which promises ongoing support, including military assistance for any conflict between Cambodia and Vietnam.

1978 - Vietnam deploys division-sized units along the Cambodian border and sponsors the establishment of an anti-Pol Pot movement called the Kampuchean (or Khmer) National United Front for National Salvation.

On 25 December the Vietnamese launch a full-scale military invasion of Cambodia, rapidly pushing aside the Khmer Rouge. Phnom Penh is captured on 7 January 1979. Sihanouk flees to China on the last flight out of the capital. Pol Pot and the defeated Khmer Rouge retreat to the country's remote western regions from where they will stage a fitful guerilla war destined to last a further 20 years.

Between one and three million Cambodians, or about one quarter of the country's entire population of about seven million, have died during the three years, eight months and 20 days of Pol Pot's rule. On a per capita basis the Khmer Rouge "revolution" is easily the deadliest in modern Asian history.

1979 - Three days after the fall of Phnom Penh the Vietnamese occupying forces establish the People's Republic of Kampuchea (PRK), governed by the KPRP and headed by Heng Samrin, a former Khmer Rouge military commander.

Already at war with the Khmer Rouge, the PRK faces further resistance from two new insurgent movements - the noncommunist Khmer People's National Liberation Front (KPNLF) headed by Son Sen, and the National United Front for an Independent, Neutral, Peaceful, and Cooperative Cambodia (FUNCINPEC) headed by Norodom Sihanouk.

China also enters the dispute, launching a limited invasion of Vietnam in February and March in retaliation for Vietnam's incursion into Cambodia. China is, however, primarily concerned by the improving relations between Vietnam and the Soviet Union.

ASEAN (the Association of Southeast Asian Nations) shares China's concerns about the spread of Soviet-backed communism in the region. Its member nations play a key role in ensuring that the United Nations (UN) continues to recognise Pol Pot's Democratic Kampuchea as the legal representative of Cambodia. The UN also withholds development aid from the KPRP government.

In August a Phnom Penh "people's revolutionary tribunal" tries Pol Pot in absentia for genocide and sentences him to death. In December Pol Pot is replaced as prime minister of the Khmer Rouge "government" by Khieu Samphan. Pol Pot remains as leader of the KCP and the Khmer Rouge armed forces.

It is reported that the Khmer Rouge are receiving military backing from China and the US. It is also reported that a former deputy director of the CIA visits Pol Pot's operational base in November 1980. During 1980 the World Food Program supplies the Khmer Rouge with food worth US$12 million.

Meanwhile, Pol Pot's wife, Khieu Ponnary, goes insane. He will divorce her and in 1985 remarry a much younger second wife with who he will have a daughter. Khieu Ponnary dies in 2003.

1982 - On 22 June the Khmer Rouge, KPNLF and FUNCINPEC join in a coalition (the Coalition Government of Democratic Kampuchea) against the Vietnamese. The agreement has been brokered by ASEAN. Sihanouk is chosen as the coalition's president, Khieu Samphan is vice president and Son Sen is prime minister.

The coalition, which proposes a general election under UN supervision once the Vietnamese have withdrawn, is recognised by the UN as the lawful government of Cambodia and funded by China, the US and Thailand.

1985 - Pol Pot officially resigns as commander of the Khmer Rouge military forces, although he retains a supervisory role.

1987 - In December Sihanouk arranges direct talks between himself and Hun Sen, the premier of the PRK. The talk's are largely fruitless but do open the lines of communication between the two sides.

1988 - In May Vietnam announces plans to withdraw 50,000 troops from Cambodia by the end of the year. By December not only have the troops gone but also the Vietnamese military high command.

In July all the parties in the Cambodian conflict attend an informal meeting in Bogor, Indonesia. Vietnam links a total withdrawal of its troops to the elimination of the Khmer Rouge. China calls for a complete withdrawal of all Vietnamese troops but rules out any role for Pol Pot in a post-settlement government. The meeting ends inconclusively, as does a subsequent meeting held in February 1989.

Meanwhile, rapprochement between the Soviet Union and China causes the Soviets to also pressure Vietnam to withdraw.

1989 - In Europe, the French Government convenes the Paris International Conference on Cambodia from 30 July to 30 August. Called to mediate a settlement between the PRK and the coalition, the conference stalls when no agreement can be reached on the future of the Khmer Rouge once all the Vietnamese troops are withdrawn. China, however, promises to cut all aid to the Khmer Rouge when a settlement is finalised.

The troop withdrawal is completed in September. The PRK remains in power, headed by Hun Sen. The country is renamed Cambodia and the constitution amended. Renewed fighting between the PRK troops and the opposition forces, including the Khmer Rouge, breaks out on the country's western frontier with Thailand.

1991 - On 23 October the four factions finally sign a peace treaty establishing a temporary coalition government under the supervision of a UN peacekeeping force. Sihanouk returns to Cambodia and is named president.

1993 - Cambodia's first multiparty elections since 1972 are held in May, although they are boycotted by the Khmer Rouge, which claims that the Vietnamese are still covertly occupying the country. When no single party wins a majority the KPNLF and FUNCINPEC form a coalition with two smaller groups.

However, Hun Sen refuses to give up control of the government, leading to a power-sharing arrangement between the coalition and the PRK.

The UN withdraws after the election and China, the US and Thailand stop their financial aid.

Pol Pot goes into hiding and continues the insurgency against the government. He is reported to be in command of a shrinking and demoralised Khmer Rouge guerrilla force based in the Phnum Dangrek Range near the northern border with Thailand. Funding for the movement is obtained through the sale of gem mining and logging concessions to Thai interests, with the revenue estimated to be worth about US$200 million a year.

1996 - The Khmer Rouge begin to split. In August Ieng Sary, Khmer Rouge foreign minister and 'Brother Number Three', defects to the Cambodian armed forces, bringing about 4,000 guerrillas with him. Ieng Sary subsequently names Pol Pot as the sole instigator of the Khmer Rouge policies of genocide. It is the beginning of the end for the Khmer Rouge, who are now reduced to just a few thousand cadres.

1997 - In June Pol Pot becomes convinced that Son Sen, the Khmer Rouge minister for defence and his friend for 40 years, is collaborating with the Cambodian Government and orders his execution. Sen's wife and children are also killed.

Pol Pot is subsequently arrested by Ta Mok, the Khmer Rouge military commander and 'Brother Number Five'. On 25 July a "peoples' tribunal" sentences Pol Pot to life imprisonment for Sen's murder. He is reported to be ailing and near death.

During the trial Pol Pot agrees to an interview with Nate Thayer, a journalist with the 'Far Eastern Economic Review'.

"First, I want to let you know that I came to join the revolution, not to kill the Cambodian people," Pol Pot tells Thayer.

"Look at me now. Do you think ... am I a violent person? No. So, as far as my conscience and my mission were concerned, there was no problem. This needs to be clarified. ...

"My experience was the same as that of my movement. We were new and inexperienced and events kept occurring one after the other which we had to deal with. In doing that, we made mistakes as I told you. I admit it now and I admitted it in the notes I have written.

"Whoever wishes to blame or attack me is entitled to do so. I regret I didn't have enough experience to totally control the movement. On the other hand, with our constant struggle, this had to be done together with others in the communist world to stop Kampuchea becoming Vietnamese.

"For the love of the nation and the people it was the right thing to do but in the course of our actions we made mistakes."

Meanwhile, Hun Sen and the PRK seize full control of the Cambodian Government in July, using force of arms to oust the coalition in an action that amounts to a military coup.

1998 - Pol Pot dies in the evening of 15 April, reportedly from heart failure, although the cause of his death remains unclear. Hours earlier he had learned from a radio broadcast that Ta Mok was willing to hand him over to the government for trial. His body is cremated on a pyre of old car tyres beside a village latrine. The site is later enclosed by a crude timber shelter roofed with old sheets of corrugated iron.

In May Cambodian armed forces capture the last stronghold of the Khmer Rouge in the country.

Postscript

1999 - In February the last remaining members of the Khmer Rouge are incorporated into the Cambodian armed forces. In March Ta Mok, the last Khmer Rouge leader at large, is arrested.

2001 - A report released by the Documentation Centre of Cambodia (DC-Cam) in July accuses seven former Khmer Rouge leaders of direct participation in the atrocities of the Pol Pot regime and verifies the existence of "a policy of mass murder devised at the highest levels of power and implemented through a coordinated chain of command."

"No longer will those most responsible for the deaths of nearly one third of the population of Cambodia during the Khmer Rouge reign be able to say they did not know," the report says.

The Documentation Centre is a private organisation set up to collect Khmer Rouge records as a historical resource for the public and as potential evidence in any future trials. It originated in the Cambodian Genocide Program at Yale University in 1995 with a grant from the US Department of State.

By September 2002 the centre has collected 5,922 pages of documents directly implicating a dozen former Khmer Rouge figures in the killings and abuses of the regime. The centre has also identified 19,400 mass graves and documented 167 former prisons, some of which were larger than the notorious Tuol Sleng.

The discoveries by the centre cause experts to revise upward the estimated number of victims of the Khmer Rouge from 1.7 million to 2.2-2.5 million.

In August 2001 the Cambodian Government passes legislation to set up a joint tribunal of local and international judges and prosecutors to try former leaders of the Khmer Rouge for genocide.

Negotiations with the UN over the shape and scope of the tribunal have been underway for a number of years, but without any final resolution. While Cambodia wants the tribunal to be governed by domestic law and to contain a majority of Cambodia judges, the UN wants to hold the authority so that it can ensure the conduct of the tribunal meets international standards.

2002 - In February the UN pulls out of the negotiations on the genocide tribunal, saying the arrangements as conceived by the Cambodian authorities "would not guarantee the independence, objectivity and impartiality that a court established with the support of the United Nations must have."

While the Cambodian Government vows to carry on with its own trials, the US State Department and the French Foreign Ministry call for an immediate resumption of talks between the UN and Cambodia.

Only two former Khmer Rouge are being held in detention awaiting trial for genocide, crimes against humanity and war crimes - Ta Mok, the military commander who arrested Pol Pot in 1997, and Kaing Khek Iev (also known as Duch), the governor of the Tuol Sleng detention centre.

Most of the senior leaders of the Khmer Rouge remain free, including Nuon Chea (also known as Long Reth), one of the members of the 'Paris student group', 'Brother Number Two', and a hard-line and unrepentant supporter of Pol Pot. The former leaders advocate the establishment of a truth and reconciliation commission similar to that set up in South Africa following the end of apartheid, rather than prosecution in a genocide tribunal.

In December the UN General Assembly passes a resolution to rejuvenate negotiations on the genocide tribunal.

2003 - Talks between the UN and Cambodia on the genocide tribunal resume at the start of January. An agreement is reached on 17 March and signed by the UN on 6 June. The tribunal will be composed of both Cambodian and foreign prosecutors and judges, with a majority of Cambodians.

At the end of the year, on 30 December, Khieu Samphan becomes the first of the former Khmer Rouge leaders to acknowledge that their regime committed genocide. "There's no more doubt left," he says.

Meanwhile, the Cambodian Government unveils a multi-million dollar plan to turn Pol Pot's cremation site and its surrounds into an official "historical tourism" zone. Under the plan, dilapidated Khmer Rouge buildings at the site will be renovated and a new access road constructed from Angkor, about 120 km to the south. The project features a purpose-built memorial, museum and theatre complex to record the genocide of the Khmer Rouge regime.

According to a report in the 3 September issue of 'The Sydney Morning Herald', former members of the Khmer Rouge, including Pol Pot's cook and housekeeper, are being recruited to act as tour guides, and new signs have been erected at 26 selected "historical" sites.

2004 - In January Pol Pot's 'Brother Number Two', Nuon Chea, announces that he is willing to face an international genocide tribunal in order to set the record straight.

"I admit that there was a mistake," Nuon Chea says, "But I had my ideology. I wanted to free my country. I wanted people to have wellbeing."

According to Nuon Chea, his key error was to not check up carefully on the work of the regime. "People died, but there were many causes of their deaths," he says, denying that millions perished.

On 4 October the Cambodian National Assembly unanimously ratifies the agreement with the UN to set up a genocide tribunal. The Cambodian Senate also approves the agreement. Although no timetable is set for the commencement of proceedings, the tribunal is expected to run for three years and cost US$57 million.

2005 - In April a deal is approved allowing a Japanese company to commercialise a large Khmer Rouge killing field site at Choeung Ek outside Phnom Penh. In return for an annual fee paid to Cambodian authorities the company will be allowed to charge tourists to enter the site.

Meanwhile, the establishment of a genocide tribunal comes a step closer at the end of April when UN Secretary-general Kofi Annan announces that the UN has received sufficient pledges and contributions "to fund the staffing of the extraordinary chambers and their operations for a sustained period of time."

According to the UN, donor nations have pledged more than US$40 million towards the running of the tribunal. Cambodia is expected to provide a further US$13 million, although the country later says it can only afford US$1.5 million.

On 15 August Cambodian Prime Minister Hun Sen warns that the tribunal may not go ahead unless donor nations contribute more funds. "It has been quite a headache for me," he says. "Sometimes, I have even thought of letting it slide."

Later in August, on the 25th, the UN announces that is has appointed Michelle Lee, a Chinese national, as the chief administrator for the tribunal.

On 30 August the US provides the Documentation Centre of Cambodia with a permanent endowment of US$2 million. Interest from the endowment will be used to assist the funding of the centre.

2006 - In February it is reported that Ieng Sary, former Khmer Rouge foreign minister and 'Brother Number Three', is receiving treatment for a heart condition at a hospital in Thailand. His wife, Khieu Thirith, former Khmer Rouge minister of social affairs, is also hospitalised, for an operation on a broken hip.

Further progress is made towards the commencement of the genocide tribunal when 17 Cambodian and 12 foreign jurists are sworn in on 3 July. The swearing in is followed by a three-day workshop during which the jurists discuss the legal procedures to be used by the tribunal.

Later in July the Documentation Centre of Cambodia provides the tribunal with over 380,000 pages of incriminating Khmer Rouge documents in order to "help speed up the investigation process."

On 21 July, Ta Mok, one of the two the senior Khmer Rouge cadres being held in custody on charges of genocide, dies.

2007 - After much wrangling the Cambodian and international judges appointed to the genocide tribunal agree on the rules for the proceedings on 13 June. On 19 July prosecutors submit a list of five former Khmer Rouge leaders who they believe should stand trial. It is reported that those named are Nuon Chea, Khieu Samphan, Ieng Sary, Kaing Khek Iev and Meas Muth, a son-in-law of Ta Mok.

Noun Chea is arrested at his home in Pailin Province and flown to Phnom Penh on 19 September. He is charged with crimes against humanity and war crimes, including "murder, torture, imprisonment, persecution, extermination, deportation, forcible transfer, enslavement and other inhumane acts."

Ieng Sary and his wife, Khieu Thirith, are arrested on 12 November. Both are charged with crimes against humanity. Ieng Sary is also charged with war crimes.

Khieu Samphan is admitted to Calmette Hospital in Phnom Penh on 13 November after suffering from "numbness" after falling from a hammock at his home in Pailin. He is arrested immediately after his release from the hospital on 19 November and charged with crimes against humanity and war crimes.

The tribunal gets underway the following day when a court is convened for a pretrial hearing of a bail application by Kaing Khek Iev. The application is denied.

Kaing Khek Iev is formally charged with crimes against humanity and war crimes on 12 August.

2008 - On 11 February 'The Independent' newspaper publishes an exclusive interview with Kaing Khek Iev.

"I and everyone else who worked in that place (Tuol Sleng) knew that anyone who entered had to be psychologically demolished, eliminated by steady work, given no way out," Kaing Khek Iev tells reporter Valerio Pellizzari.

"No answer could avoid death. Nobody who came to us had any chance of saving himself. ...

"It was Ta Mok who had ordered all the prisoners to be eliminated. We saw enemies, enemies, enemies everywhere. ...

"I was cornered, like everyone in that machine, I had no alternative. Pol Pot, the No. 1 Brother, said you always had to be suspicious, to fear something. And thus the usual request came: interrogate them again, interrogate them better.

"If I had tried to flee, they were holding my family hostage, and my family would have suffered the same fate as the other prisoners in Tuol Sleng. If I had fled or rebelled it would not have helped anyone."

2009 - Kaing Khek Iev's trial begins on 17 February with an opening procedural session. When the trial resumes on 30 March Kaing accepts responsibility for his crimes.

"I recognise that I am responsible for the crimes committed," he says. "I would like to express my regretful and heartfelt sorrow."

In a later session, Kaing blames the policies of the Nixon administration for the rise of the Khmer Rouge. "I think the Khmer Rouge would already have been demolished" by 1970, he says.

"But Mr Kissinger and Richard Nixon were quick (to back coup leader Lon Nol), and then the Khmer Rouge noted the golden opportunity. ...

"Prince Sihanouk called on the Cambodian people to go and join the communist Khmer Rouge in the jungle and that allowed the Khmer Rouge to build up their troops from 1970 to 1975."

Talking about the establishment of Tuol Sleng, Kaing says, "Pol Pot was the one who initiated the idea, Son Sen implemented it and Nuon Chea is the one who did the follow up. This is from my observation and from the surviving documents. ...

"The principle was that whoever was arrested and interrogated had to be smashed. That meant be killed. ...

"Everyone who was arrested and sent to S-21 (Tuol Sleng) was presumed dead already. ...

"No one was entitled to release them. Even Pol Pot, the most senior person in the Khmer Rouge, acknowledged that he had no right to release any people. That was the party line. ...

"Pol Pot was a murderer. He was the greatest criminal father of Cambodia. ... I did not think of Pol Pot as a patriot, he had blood on his hands."

Kaing Khek Iev's trial concludes at the end of November. On 26 July 2010 he is found guilty as charged and sentenced to 35 years jail. Sixteen years are deducted from the sentence for time already served.

Both the prosecution and defence lodge appeals against the sentence. The defence also seeks to have the conviction overturned.

The appeal ruling is handed down on 3 February 2012. Kaing Khek Iev's sentence is increased to life.

Meanwhile, the charges against Nuon Chea, Khieu Samphan, Ieng Sary and Khieu Thirith are expanded to include genocide. The four are formally indicted on 16 September 2010. All claim to be innocent.

2011 - In November, Khieu Thirith is found to be suffering from dementia. She is declared unfit to stand trial but remains in custody. Opening statements in the trial of the remaining three defendants begin on 21 November.

"The accused cannot credibly claim they did not know and had no control over the crimes that occurred," says prosecutor Andrew Cayley. "These crimes were the result of an organised plan developed by the accused and other leaders. ... They cannot be blamed solely on Pol Pot as some of the accused may try."

Speaking in rebuttal, Noun Chea says the Khmer Rouge acted to save Cambodia from an invasion by Vietnam. "The Vietnam factor is the main factor that caused confusion in Democratic Kampuchea from 1975 to 1979," he says.

"(After the end of the Vietnam war) Vietnam's cadres still continued to remain discreetly on Cambodian soil in order to conquer this country in accordance with the ambition to occupy, annex and swallow Cambodia and rid Cambodia of her race and ethnicity."

"We wanted to free Cambodia from being a servant of other countries, and we wanted to build Cambodia as a society that is clean and independent, without any killing of people or genocide," he says.

Khieu Samphan says that US bombing of Cambodia led to the rise of the Khmer Rouge. "You seem to forget that between January 1970 and August 1973 - that is, the period of two and a half years - the United States carpeted the small Kampuchean territory with bombs," he says.

"Could you imagine what my country faced after such a bloody killing and war? Can you imagine what the situation was like for the Cambodian people and the country as a whole during such carpet bombings?"

When questioning of the defendants begins at the start of December, Noun Chea continues to blame Vietnam for the atrocities committed during the Khmer Rouge period. "These war crimes and crimes against humanity were not committed by the Cambodian people," he says. "It was the Vietnamese who killed Cambodians."

Others who knew him have elaborated on this description, calling Pol Pot calm, cold-blooded, extremely secretive, and above all paranoid - traits that allowed him to oversee the genocide of hundreds of thousands of innocent men, women and children.

The last word here goes again to Sihanouk.

"Pol Pot does not believe in God but he thinks that heaven, destiny, wants him to guide Cambodia in the way he thinks it the best for Cambodia, that is to say, the worst. Pol Pot is mad, you know, like Hitler."