PHNOM PENH — A familiar feeling stirs in my gut. It’s not the delicious lunch that was redolent of lemongrass and basil. It’s a slightly sickened, very off-putting sensation I’ve experienced before on numerous visits to Yad Vashem, the Holocaust museum and memorial in Jerusalem, and to the sites of former Nazi death camps in Europe.

It’s death – by the millions.

Here at Cambodia’s Killing Fields, the setting is peaceful and sylvan. Hills roll, the grass is green and birds sing. Our guide, an earnest young man named Buntheng, counsels us not to be alarmed when we see bits of off-white bone and scattered teeth on the ground.

“They come up after the rains,” he says with a shrug.

The Choeung Ek Genocidal (sic) Center, a former orchard about 15 kilometres southwest of this country’s motorbike-choked capital, is many things: education facility, museum and the place where up to 20,000 people were slaughtered under the maniacal Khmer Rouge regime of Pol Pot.

It is the best known of the thousands of killing fields in this still-traumatized nation, a stark reminder of the atrocities of the late 1970s that claimed between two and three million lives.

Few nations (Rwanda comes to mind) have suffered this much human loss in such a short time. Out of a 1970 population of some seven million, Cambodia lost nearly four million people in the ’70s to war, rebellion, man-made famine and mass murder.

It was on the last that Pol Pot made his name. He became leader of Cambodia in 1975, and for the next four years, his Khmer Rouge remade the nation along the most extreme Marxist lines imaginable. The aim was to transform “Kampuchea” into a rural, classless society where there were no rich, no poor and no exploitation.

 To accomplish this, they abolished money, free markets, normal schooling, private property, transportation, religion, and even traditional Khmer culture.

Public schools, pagodas, mosques, churches, universities, shops and government buildings were shut or turned into prisons, stables, “re-education camps” and granaries. Even certain clothing – loose-fitting black shirts and pants with red-and-white scarves – was mandatory for Khmer Rouge cadres.

 Teachers, writers, civil servants and other “intellectuals” were lumped with “bourgeois” merchants and urbanites, and shipped by the truckload to places such as this.

The signposts here tell the story. Prisoners arrived from Tuol Sleng (Security Prison 21, or simply S-21), the notorious Khmer Rouge interrogation and torture facility from which all of seven people came out alive.

“When the trucks arrived,” explains one sign, “the victims were led directly to be executed at the ditches and pits or were sent to be detained in the dark and gloomy prison nearby.”

 Sound familiar? Between 200 and 300 unfortunates arrived every day this way. Buntheng informs us that they were not shot, as bullets were scarce, but beaten to death with mallets, clubs, hatchets and other implements displayed in the adjacent museum. Even the razor-sharp edges of palm fronds were used to slit throats.

Another sign points to the “Chemical Substance Storage Room,” which housed DDT and other toxins used to kill off victims who were buried alive, and to mask the stench of death.

One mass grave holds the bodies of 166 victims “Without Heads.” Heartbreakingly, babies and children were slammed to death against the “Killing Tree,” now adorned with brightly coloured bits of string.

Of 120 mass graves here, 86 have been excavated. And apart from the teeth and bone fragments, bits of brown cloth stick out from the ground all over the place. They’re not rags, but the clothing of victims buried barely beneath your feet.

 It’s not subtle.

 The greatest punch is at Choueng Ek’s centrepiece, a pagoda-like Buddhist stupa, or reliquary. The 17-tier memorial has acrylic glass sides and brims with more than 5,000 human skulls carefully piled one atop the other. Many show clear signs of having been shattered or smashed in.

The Cambodian people have been through a lot, yet remain gentle and patient, even in the face of justice that moves at a glacial pace.

Whereas the Nuremberg trials began almost immediately after the end of World War II, war crimes trials for Khmer Rouge murderers did not begin until 2007, when a special court established by the government and the United Nations four years earlier to prosecute Communist leaders started to convene.

 To date, there has been one conviction.