From his small home in rural Kamrieng district last week, accused mass murderer Ta An reflected on past “mistakes” but said none of them included his role in Pol Pot’s infamous Khmer Rouge regime.

Anticipating visitors, the now-frail 83-year-old, who was charged earlier this year with premeditated homicide and crimes against humanity, brandished a crumpled letter.

“Information for journalists and others. You are not allowed to be here, and I respectfully ask that you leave immediately. I will not make any comments or answer any questions”, it read, before listing the contact details of his three lawyers.

But after handing over the letter, Ta An – whose real, albeit lesser-known, name is Ao An – proceeded to talk in detail about his past, professing innocence for atrocities he is accused of committing during the four-year rule of the agrarian regime, which oversaw the deaths of an estimated 1.7 million people.

“I will not take any responsibility,” he said. “I admit that I made mistakes during the [civil] war. But after the war, I was not the one who killed people, so I cannot be responsible for that.”

While An admitted to killing people during the war against Lon Nol that preceded Pol Pot’s authoritarian rule, he said that such “mistakes in wartime are unavoidable”.

“Killing existed during the war, it is inevitable, but I did not kill anyone after the war,” he maintained.

In March, An, who now enjoys a quiet retirement in his remote hometown, was charged unilaterally by Mark Harmon, then-international co-investigating judge at the Khmer Rouge tribunal, in the face of strong government opposition.

The charges of premeditated homicide and crimes against humanity – including, among others, extermination, imprisonment and persecution on political and religious grounds – cover alleged atrocities committed during the regime at the Kok Pring execution site, Tuol Beng security centre and Wat Au Trakuon security centre.

In 1977, An and his Southwest cadre seized power of the Central Zone, with An becoming its deputy secretary, according to a prosecution document detailing the allegations, which was leaked to New Zealand’s parliament in 2011.

“The purged cadre from the Central Zone either ‘disappeared’ and were never seen again, or were arrested and taken to S-21 or other prisons, where they were subsequently executed,” it says. “The families of the purged cadre were often arrested and killed as well.”

According to the document, “following the arrival of Ta An and the Southwest cadre in the Central Zone, there was a dramatic increase in the number of arrests, killings and disappearances, and a worsening of general living conditions, amongst the general population”.

At Wat Au Trakuon security centre, it says, as many as 32,690 people were killed. The “heaviest period of killing” followed Ta An’s purge of the Central Zone.

“The prisoners detained in the Wat were subject to inhumane conditions before being taken to the adjoining plantation area for execution,” the document says.

Similarly, at Kok Pring, where about 1,000 people were killed, “after the Southwest cadre arrived, an ‘intense purge’ of local cadre occurred, disappearances began, work requirements became harsher, and ‘people were told to identify other people with bad tendencies’”.

But despite the accusations, Ta An said he was merely a victim of circumstance and a defender of then-Prince Norodom Sihanouk, who had been deposed by Lon Nol.

From exile in China after his ouster, Sihanouk had outwardly aligned himself with the Khmer Rouge – though he would spend much of its reign under house arrest – and had issued a call over the radio for Cambodians to join the Khmer Rouge and take up arms against Lon Nol.

“What Cambodian could escape the Khmer Rouge regime? How was I supposed to do anything other than what the situation required me to do?” An asked.

“A regime fell, I became a Khmer Rouge official, but the root cause of this was His Excellency Lon Nol, who set up a coup and a giant demonstration. If I am accused of being a Khmer Rouge official, how about the King? Was he Khmer Rouge?”

Ta An said he had no choice but to join the communist rebels. “They gathered people for the demonstrations; a person who refused to join would lose his house. What man at my age could escape from that event?” he said. “Everything I have done is for the King.”

Like Meas Muth, the Khmer Rouge navy chief and Case 003 suspect who said in an interview earlier this year that he had found forgiveness through religion, Ta An said he believes only Buddha can judge him.

“This life depends on karma, but in the next life, I don’t want to experience such a thing [as I have in this one]. I served the King, and as result I became a victim. I am so resentful,” he said.

Ta An added that he was concerned he would not be given a fair trial.

“I have killed no one, so what can I do? People come and investigate. It will be alright if the investigation is fair, but what will it be if the investigation is not fair?”