#HumanRights : 40 year ago the end of communist and bloody regime of Khmer Rouge and dictator Pol Pot.

Cambodian soldiers take part in an event to celebrate the 40th anniversary of the overthrow of the Khmer Rouge and of the communist and bloody regime of Pol Pot at the Olympic stadium in Phnom Penh, Cambodia.

Tens of thousands of Cambodians packed a stadium in Phnom Penh Monday (Jan 7) to celebrate the 40th anniversary of the expulsion of the brutal Khmer Rouge regime - a day strongman Prime Minister Hun Sen called the country's "second birthday".

The ultra-Maoist Khmer Rouge, led by Pol Pot, installed a reign of terror in 1975 that left two million Cambodians dead from starvation, hard labour, torture and mass executions.

It ended on January 7, 1979, when Hun Sen, a former Khmer Rouge cadre, led Vietnamese forces into the capital to expel the murderous regime.

The 66-year-old premier hailed the day as Cambodia's "second birthday" at an elaborate ceremony in Phnom Penh's Olympic Stadium, where he was joined by traditional Khmer apsara dancers and marching bands.

"Today we celebrate this ceremony in order to recall unforgotten memories of the most heinous crimes of Pol Pot's group," Hun Sen told the crowd, and thanked Vietnam for saving the country.

A UN-backed tribunal found two top Khmer Rouge leaders guilty of genocide in a landmark ruling in November.

The feisty prime minister - who has ruled the country for 33 years - also took the opportunity to revisit history, hitting back at countries which continued supporting the Khmer Rouge after its ouster.

These countries ... boasted about humanitarian and human rights and democracy (but) unjustly blocked" when the people needed assistance from the international community, he said, without naming any specific nation.

After the regime was toppled in 1979, Hun Sen found his Vietnam-backed government caught between geopolitical forces as the US sought to keep the ousted Khmer Rouge at the table in the United Nations.

The Southeast Asian country in recent years has tilted towards China thanks to loans for infrastructure and few complaints on human rights issues.

Last July, his party won a much-criticised election handily, after his government dissolved the country's main opposition group and jailed its leader - effectively turning Cambodia into a one-party state.

Hun Sen on Monday vowed to "deny the actions of extremist opposition politicians and the foreign circle behind them", claiming that they were trying to push Cambodia from a democratic path.

Critics say Hun Sen's 33-year reign, as one of the longest serving premiers in the world, has created a more repressive Cambodia, where journalists, rights defenders and opposition politicians are routinely jailed for dissent.

Experts combine technology and fieldwork to find mass graves from Khmer Rouge era

A pilot project is twinning technology and fieldwork to locate remains of victims of the Khmer Rouge, the ultra-Maoist regime whose quest to build an agrarian utopia that left almost two million Cambodians dead.
A man walks gingerly over a small field in rural Cambodia, pushing a lawnmower-like contraption that deploys ground-penetrating radar to unearth clues of mass graves.

The pilot project is twinning technology and fieldwork to locate remains of victims of the Khmer Rouge, the ultra-Maoist regime whose quest to build an agrarian utopia from 1975-1979 left an estimated two million Cambodians dead.

Hacked to death, starved, overworked or ravaged by illness, their bodies were dumped in hastily dug pits all over the country. They were thrown in rice paddies, down caves and on the grounds of Buddhist monasteries.

Many of the "Killing Fields" have been logged, providing experts with an estimate of 20,000 mass graves - which is defined as a pit containing four or more bodies - throughout the country.

But researchers are now turning to radar to uncover more details on the existing sites - such as how many bodies they might contain - and find new ones.

"This is the first time ever that we have used high-end technology in Cambodia to locate mass graves created by the Khmer Rouge," said Mr Pheng Pong-Rasy from the Documentation Centre of Cambodia (DC-Cam), which is overseeing the effort.

Pol Pot whose real name is Saloth Sar. He was the Prime Minister of the Democratic Kampuchea and leader of the Khmer Rouge.

He added that DC-Cam decided to start the new search in the eastern province of Prey Veng, where the Khmer Rouge's revolutionary movement had some of its early gains.

"The children must know their own history, what happened in their location," he said.

They began in late October next to buildings at Mesang High School - specifically plots close to some concrete toilets and an outdoor cafeteria.

The area was once a worship site but the Khmer Rouge converted it into a place for executions. After the regime fell, a school was built nearby.

Students and residents helped clear the overgrown area and operators from SparrowHawk Far East, a new Phnom Penh-based company tapped to test out the idea, walked over it sending radar signals below that can later be developed into three-dimensional images.

"When there is an object underground or the ground has been disturbed before, if there was a hole dug, it will give off a different signature," managing director Michael Henshaw said.

"It's good for finding underground utilities like water pipes and electric pipes, it's good for archaeology to find old structures underground," he said. "But it's also been used to find mass graves."

Khmer Rouge researchers have since the 1990s relied mainly on meticulous interviews with the regime's victims and perpetrators to pinpoint the locations of mass graves.

Elsewhere, radar has helped locate indigenous burial sites - graves from the Spanish Civil War in 1936-1939 and victims of the 1990s conflict in Bosnia.

In September, it also aided in the discovery of at least 166 bodies in the Mexican state of Veracruz, a territory plagued by drug cartels.

Mr Henshaw said the results can bring about a greater understanding of what happened in Cambodia.

"We can try to put a better number on how many victims there actually were," he said.

As curious students look on, Mr Henshaw examines preliminary results on a screen while the sun, interrupted by the occasional rainshower, beats down.

He points to what he calls anomalies, which look like small ridges next to each other, possibly signifying decomposed remains.

"But this definitely tells you that there is something under the ground, and there's a lot of it."

SparrowHawk is plugging the data into special software and preparing a full report on their findings, and DC-CAM will then make a decision on how far to replicate the study.

No matter the results from Prey Veng, there will be no excavations and reburials. In keeping with local tradition, the remains will not be disturbed and will stay where they are.

"They already died without justice, so if we dig up graves, it will destroy their souls," Mr Pong-Rasy said. "We just want to know how many bodies are in the graves."

DC-Cam maintains a database of mass graves previously discovered and it has provided information on sites to a war crimes tribunal that has convicted two top Khmer Rouge officials and a chief jailer.

But Mr Youk Chhang, DC-Cam's director, said the picture is still incomplete.

"Crimes do not end at a tribunal," he said, adding that a better future for Cambodia required "understanding the horrors" of its past. "We should not stop searching for the answers".