A pre-teen girl with almond-shaped eyes, a wide nose, and thin mouth slightly agape looks down the camera’s lens. Her age is unknown, though she couldn’t be more than 12. She hasn’t a name anymore—it’s Year Zero, nothing of the past shall remain, nothing has a name—but pinned to her shirt is an index card: 408. The photo is one of thousands taken of those awaiting massacre during the Khmer Rouge-era Cambodia, those four years when Pol Pot’s fanatical communist sect killed a larger percentage of their fellow countrymen than any other 20th century genocidaire. Girl 408 too would be brutally murdered.

The next photo: 389 stands holding hands with a man slightly out of frame—a giant of a man—whose eyes are blindfolded with a rag. Their interlocked fingers are an expression of fear, not tenderness. They will both be dispatched with a bullet; perhaps bludgeoned with an axe handle; possibly tortured until their internal organs surrender. We don’t have specifics, but we know she’ll be executed. Because at Khmer Rouge’s S-21 killing center, everyone was. All of them. Of the tens of thousands of innocents “processed” by S-21’s staff of lunatics and sadists, only seven are known to have survived.

Almost three decades later, two men ultimately responsible for the murders of 389 and 408 sit in a Phnom Penh courtroom, awaiting their fate. Sunday, the prosecution will offer its closing statement to the court in the trials of Nuon Chea, known as Brother Number Two (Pol Pot, who cheated justice by dying of old age, was Brother Number One) and the “chief ideologist” of the regime, and Khieu Samphan, its head of state. In 1979, as the regime collapsed, it was Nuon Chea who ordered the remaining 500 prisoners at S-21 executed.

As one regional newspaper observed, the Khmer Rouge trial has been met with “widespread indifference” in Cambodia. It’s unsurprising, considering the United Nations-backed tribunal has been mired in scandal and took over a decade to notch its first trial and conviction. One Phnom Phen-based writer covering the trial reminded readers that, “the Khmer Rouge retained a seat in the General Assembly for years after they were toppled—in what observers consider a shameful chapter in UN history.” In the Western media, the Chea and Samphan trials have barely merited a mention.

Because while we recall Auschwitz and the Nazi practice of tattooing numbers on prisoner arms (in S-21 prisoner photos, the identity number was often pinned through the skin of a prisoner’' bare chest), the arbitrary homicide, and the Teutonic efficiency of the extermination camp, few know of S-21 or any of the Khmer Rouge’s countless other charnel houses.

Maybe they’ve seen Sam Waterston and John Malkovich in The Killing Fields, the 1984 film that starkly dramatized Pol Pot’s inhuman regime and his troop’s sinister evacuation of Phnom Penh. But as historian William Shawcross noted, “the issue [of Cambodian genocide] never reached critical mass...And there was no broadly based campaign of protest in the West as there was, say, over abuses of human rights in Chile.” (Sen. George McGovern, who just six years previous was a peacenik presidential candidate, was an exception: he advocated military intervention in Cambodia to stop the slaughter.)

It is, in many ways, a forgotten genocide—odd when considering the unique savagery and cruelty of the perpetrators. The term “Orwellian” is often misapplied and misunderstood, but the closest manifestation of newspeak and doublethink can be found in Pol Pot’s Cambodia. Here is an actual prisoner confession recovered from S-21, a statement so confused and abject that Orwell would likely have dismissed it as overly drawn:

“I am not a member of the CIA. I confessed to being CIA when confronted with my guilt. I beg the Organization to [kill] me because I have not followed the revolution...I deserve to die because the Organization had [once] trusted me. I no longer wish to live, make no protests to the Organization, by way of seeking justice. But I must declare that in my heart I have not betrayed the Organization at all. I declare my guilt...because I am dying. Long live the glorious revolution! Long live the Revolutionary Organization!”

Indeed, one could convincingly argue that Cambodia was the home to the 20th century’s most Orwellian regime and site of its worst genocide: most reliable estimates calculate that an astonishing 25 percent of the country’s total population was murdered by the regime. Between 1975-1979 an estimated two million innocents were murdered. In 2012, more than 40 years after he joined the Khmer Rouge, Comrade Duch, the slavemaster and torturer who operated S-21, was sentenced to life in prison. ‘The crimes committed by [Duch],” the court declared, “were undoubtedly among the worst in recorded human history.” It was the first conviction of a Khmer Rouge criminal by the UN-backed commission.

So who besides Duch has been punished for these record-shattering atrocities? If Nuon Chea and Khieu Samphan are sent to prison this week, it will bring the total number of Khmer Rouge leadership convictions to three. Some previous defendants died before trial. Some were declared mentally “unfit” for prosecution. Others are protected by crooked politicians. Much of this is thanks to the consistently incompetent United Nations, but much more is the responsibility of the current Cambodian government, which happens to be led by a former Khmer Rouge military commander. As Human Rights Watch lamented, “[Cambodian] Prime Minister Hun Sen has never been committed to prosecuting more than a few Khmer Rouge leaders, apparently to protect members of his party and government who were also in the Khmer Rouge.”

It is indeed vital for the court to secure these convictions, for the monstrous Nuon Chea and Khieu Sampha to die in a dank Cambodian prison. As trial prosecutor Chea Leang said, the court “demonstrates that crimes of such magnitude and severity will not be forgotten and that those responsible will be held to account.” But they have been forgotten. And almost none of those responsible have ever been held to account. This would be a good, if underlooked, precedent.