Last week the Khmer Rouge tribunal handed down a historic verdict against two elderly leaders of the regime that claimed at least 1.7 million lives, legally declaring for the first time that genocide had occurred in Cambodia in the 1970s.

Key points: There are still Khmer Rouge leaders left but just how senior they were is debated

There are still Khmer Rouge leaders left but just how senior they were is debated Australia has funded the trials and ending them early could reinforce a "culture of impunity"

Australia has funded the trials and ending them early could reinforce a "culture of impunity" A man allegedly responsible for the deaths of two Australians could also avoid trial

But days after that decision, Cambodia's Deputy Prime Minister Sar Kheng declared there were no more Khmer Rouge leaders left to try and that Khmer Rouge court proceedings would end once Nuon Chea and Khieu Samphan's appeals were heard.

"As for [other top Khmer Rouge leaders] to be brought to justice, there are no more left," he said, according to local media.

"Our policy now [is that the] process has ended."

So does this mark the end of the lengthy tribunal for the Khmer Rouge? Would it be premature? And if so, should Australia care?

Are there really no Khmer Rouge leaders left?

No, there are still currently three men out there who have been charged with a raft of crimes against humanity — they have just never been sent to trial.

Who has been tried at the tribunal? Kaing Guek Eav: Known as Duch, he was the head of S-21 prison where around 12,000 people were tortured and murdered

Kaing Guek Eav: Known as Duch, he was the head of S-21 prison where around 12,000 people were tortured and murdered Nuon Chea: Second-in-command to Pol Pot. Convicted of crimes such as genocide, extermination, and torture

Nuon Chea: Second-in-command to Pol Pot. Convicted of crimes such as genocide, extermination, and torture Khieu Samphan: The former head of state. Convicted of similar crimes to Chea

Khieu Samphan: The former head of state. Convicted of similar crimes to Chea Ieng Sary: The former foreign minister, died during proceedings against him

Ieng Sary: The former foreign minister, died during proceedings against him His wife and former social affairs minister, Ieng Thirith, was ruled unfit for trial due to dementia — she later passed away

That includes alleged naval commander Meas Muth and two others, Yim Tith and Ao An.

The jurisdiction of the Extraordinary Chambers in the Courts of Cambodia (ECCC) — commonly known as the Khmer Rouge tribunal — is to try only those deemed "senior leaders" and those "most responsible" for the Khmer Rouge's crimes.

But just how senior and responsible these three were continues to be the subject of heated legal debate.

Some of the more recognisable figures of the regime — including Pol Pot himself — died before they could be put on trial.

Is there any political interference from within Cambodia?

It has long been known that the Cambodian Government did not want the trials to continue beyond Chea and Samphan.

Pol Pot died before he could be put to trial. ( AP )

In fact, Mr Kheng's comments echo remarks made years earlier by Prime Minister Hun Sen, who said that if the trials proceeded civil war would follow.

The hybrid tribunal has seen a pattern emerge where international lawyers and judges want the suspects to be prosecuted, but their Cambodian counterparts want the cases dropped, just like the Government.

According to Dr Rebecca Gidley, a tribunal expert from the Australian National University, Mr Kheng's "definitive" statements did not include the usual caveats about respecting the independence of the court.

A Human Rights Report found links between PM Hun Sen and the Khmer Rouge. ( AP: Heng Sinith )

"What's actually happening at the ECCC, I would argue, is that Hun Sen has demonstrated [that] not only can he control the Cambodian judiciary, but even when you insert international judges and a role for the United Nations, you can still control the outcome," she said.

"Part of what the ECCC's legacy will be is entrenching the culture of impunity, rather than helping to end it."

The ruling Cambodian People's Party narrative is that it expelled the Khmer Rouge long ago, but go far enough down the chain of command and you will reach Hun Sen himself, as well as several of the country's most powerful political figures.

A Human Rights Watch report from 2015 found that Hun Sen was a mid-level commander in the Khmer Rouge's East Zone, where Cham Muslims were subjected to systematic crackdowns — which has been ruled as genocide by the court.

The final surrender of the Khmer Rouge in Anlong Veng in 1999. ( Supplied: Khun Ly, file )

So why should Australia care?

The Australian Government has sunk about $57 million into the trials and is the third-largest foreign donor behind Japan and the United States.

Dr Gidley added that one of the reasons countries like Australia funded trials like this was to end cultures of impunity and strengthen the rule of law.

Australian David Lloyd Scott was killed by the Khmer Rouge when he sailed into Cambodian waters in the 1970s. ( Flickr: The Naked Ape )

Having the trials end prematurely without justice for all could arguably be seen as not getting a full return on our investment, but even putting financial stakes aside, there may also be more personal reasons.

Two Australian yachtsmen — David Lloyd Scott and Ronald Dean — drifted into Cambodian waters and were allegedly captured by the navy under alleged commander Mr Muth in the late 1970s.

They were sent to their deaths after being tortured, and it is possible they may have been among a handful of Westerners taken out into the streets of Phnom Penh, placed under rubber tyres, and burnt alive.

"We have argued that the evidence shows that Meas Muth was in charge of the [Democratic Kampuchea] navy and [was] responsible for the arrest and transfer of the Australian sailors to S-21, the interrogation and killing centre in Phnom Penh," said William Smith, an Australian lawyer and tribunal deputy co-prosecutor.

"There he knew they would be tortured and killed amongst many other Vietnamese and Cambodians who were also sent there by him."

Meas Muth, the alleged Khmer Rouge naval commander, leads a funeral procession for Khmer Rouge cadre Ta Mok. ( DC-Cam Archives )

Mr Muth's lawyer, Michael Karnavas, said that until a closing order either dismissed or indicted his client, there was no point speculating about the future of his case.

"Comments by the Government may have weight with the public but not with the judges," he said.

"We are preparing the case to go the distance."

Cambodian politics can also have a ripple effect in Australia.

An ABC investigation recently revealed that Cambodian elite were amassing millions of dollars in Melbourne property portfolios while death threats were made against critics within the diaspora.

The brazen shooting of beloved political analyst Kem Ley in 2016 saw his widow and five sons seek asylum in Australia, where they have since received death threats.

So could the tribunal's end really be imminent?

Photos of some of the thousands of people who were locked in S-21 and eventually killed. ( ABC News: Erin Handley )

The trials are more likely to go out with a whimper rather than a bang, Dr Gidley said.

"If they shut down the court in a non-legal manner, then they sort of tarnish their reputation," she said, adding it was more likely they would operate within the structure of the court to drop the cases quietly.

A 1979 photo of the exterior of S-21 prison, where thousands were murdered. ( Supplied: Ho Van Tai )

"They need to sweep as much of the interference behind closed doors and cloak it in legal language."

Mr Smith said the court could not be closed down until its judicial work had been completed, and tribunal spokesman Neth Pheaktra said neither Cambodia or the UN could end the proceedings as it was up to the judiciary.

Mr Pheaktra declined to comment on the Deputy Prime Minister's remarks, but said the court was continuing its work and stressed that judges and lawyers "work and decide independently without any interference".