The head of Tuol Sleng, the Khmer Rouge prison where more than 15,000 men, women and children were tortured and killed, has just been sentenced to 35 years in jail (though he is expected to serve just 17).
Kaing Guek Eav, or Comrade Duch, is the first senior Khmer Rouge cadre to be tried and convicted by an international tribunal  in the Cambodian capital, Phnom Penh. The case has brought the barbarity and callousness of the Pol Pot regime -- which caused the death of roughly a quarter of the country's population between 1975 and 1979 -- once more to the world's notice.
It would be easy to paint Duch as a monster. At one level, clearly he is. But to lay the blame for the atrocities of the Khmer Rouge at the door of a few "evil" people is too simplistic. Prime Minister Hun Sen (himself ex-Khmer Rouge) would rather the legal proceedings go no further than the current five cases  -- which is an acknowledgement that the layers of complicity, whether voluntary or forced, run deep and wide. "If as many as 20 Khmer Rouge are indicted to stand trial and war returns to Cambodia, who will be responsible for that?" he asked last year.
Hun Sen may well be justified in fearing what could be unearthed, both because of the prominence of the politicians who could be fingered and for the effect delving into the past could have on a country that needs to preserve and build on shallow foundations of reconciliation. (It is only 13 years since different armed forces last fought each other in the capital).
But another way of looking at the larger picture lies not in levelling further accusations, but in trying, somehow or other, to understand how so many people could have acted so terribly.
For the good of Cambodia
One man in particular is well placed to comment. François Bizot is a French scholar who worked at the Angkor Conservation Office in the early 1970s. In October 1971 he was captured and, accused of being a CIA spy, held by the Khmer Rouge at Camp M13 in the far north of the country. The overseer of the camp was . . . none other than Comrade Duch.
Bizot wrote a remarkable memoir of his time in the camp and of the subsequent fall of Phnom Penh to the hardline Maoist regime, which he witnessed. "The Gate"  was considered to contain such valuable insights that he was the first witness  called to testify in Duch's trial when it began in April last year.
Bizot recalled that initially he thought those who commit unspeakable crimes must be "of a different species", but he came to realise that the truth was "much more tragic, much more frightening". Duch was "a man who resembled others", "polite", "a tireless worker", "a Communist-Marxist ready to lose his life if necessary for his country and for the revolution".
"The humanity that is his own," said Bizot, "was obviously not an obstacle to the killings he perpetrated." But "the final goal of his commitment was the good of Cambodia and fighting injustice".
The ambiguity that has haunted Bizot ever since is that he owes his life to this man. It was Duch, the jailer of Tuol Sleng, who wrote the report to his superiors in "Angkar", the party's Big Brother-like organisation, that secured the Frenchman's release. No other westerner is known to have survived imprisonment by the Khmer Rouge.
"Trying to understand is not to forgive," said Bizot. No, not in this case, it isn't. But trying to understand is necessary if we are to remember that "the banality of evil" was not confined to Hitler's Germany. (You can read a comparison of the Khmer Rouge with the Nazis in Der Spiegel here .)
To make a monster of Duch is almost to take away his responsibility. A psychiatric report on him commissioned by the court concluded that the prisoner was medically and mentally normal; he could, in theory at least, one day be reintegrated into society.
It is the fact that Duch, and countless others in Cambodia, were so ordinary which makes their crimes so chilling. That is what we should try to understand. And if we cannot, if the enormity of their wickedness is ultimately beyond comprehension -- then it is certainly what we should remember.