|A handout photo shows Duch, whose real name is Kang Kek Ieu, posing for a picture at the military prison in Phnom Penh.|
A former Khmer Rouge prison chief Tuesday was handed over to Cambodia's UN-backed tribunal for questioning in the most concrete move so far to try those responsible for the country's genocide.
Duch, whose real name is Kang Kek Ieu, is the only Khmer Rouge figure in custody ahead of Cambodia's long-stalled genocide trials. He had been held in a military prison since 1999.
"The tribunal has issued a warrant asking to transfer Duch and we handed him over this morning to the tribunal," said Ngin Sam An, a military court investigating judge who has overseen Duch's case since his arrest.
Tribunal officials said that Duch was being questioned by the judges, who were expected to issue an order that would see the 65-year-old formally detained by the court.
"Duch was brought for an initial interview," spokesman Reach Sambath told AFP, stressing that Duch was not yet convicted of any crimes.
Duch is one of five former leaders widely thought to be under investigation.
His transfer to the tribunal is a significant step in Cambodia's efforts to try those responsible for one of the worst atrocities of the 20th century.
Up to two million people died of starvation and overwork, or were executed, under the Khmer Rouge's 1975-79 communist regime.
The Khmer Rouge also abolished religion, schools and currency, exiling millions to vast collective farms in a bid to create an agrarian utopia.
These crimes were part of a "common criminal plan constituting a systematic and unlawful denial of basic rights," prosecutors said earlier this month after submitting their cases for investigation.
The names of all those under investigation have not been made public.
But prosecutors are reportedly also seeking charges of genocide and other crimes against former Khmer Rouge head of state Khieu Samphan, as well as regime leader Pol Pot's deputy Nuon Chea and foreign minister Ieng Sary.
Duch ran the Khmer Rouge's notorious Tuol Sleng prison, a former high school that was converted into a torture centre.
Trials are expected next year in what many see as the last chance for Cambodians to get justice for crimes committed by the regime.
Pol Pot died in 1998, and rights groups and legal advocates are concerned that other ageing figures from the regime -- most of whom live freely in Cambodia -- will also die before being brought to court.
Khieu Samphan told AFP Tuesday he was not alarmed by Duch's summons, saying he did not fear arrest.
"There is no reason to arrest me. I will go to the tribunal if they ask me to," he said from his home in northwestern Cambodia.