The navy commander of Cambodia's former Khmer Rouge regime was formally charged on Monday for genocide, homicide and other offences by a United Nations-backed war crimes tribunal.
The charges against Meas Muth came despite opposition from the country's Prime Minister Hun Sen, who was a mid-level Khmer Rouge commander before defecting while the group was still in power.
The tribunal, which operates under a system that pairs international and Cambodian judges, prosecutors and lawyers, said Muth appeared voluntarily to hear the charges against him from Investigating Judge Michael Bohlander.
Muth had previously been charged in absentia and two arrest warrants had been issued, but Cambodian police had refused to arrest him.
It was not clear what motivated Muth to volunteer to appear before the judge a year after the original summons was issued.
The charges against him include homicide, genocide, crimes against humanity and other offences.
READ MORE: Four decades after Cambodia's Year Zero
The tribunal - the Extraordinary Chambers in the Courts of Cambodia - found three defendants guilty in earlier trials, but Cambodian officials have not cooperated in prosecuting new suspects.
Hun Sen has repeatedly said that if the tribunal targets more defendants, it could incite former Khmer Rouge members to start a civil war. Aside from his political allies, however, few people share his belief, since the Khmer Rouge became a spent force almost two decades ago.
Because of government opposition, Cambodian court staff will not take part in the proceedings against Muth.
The Khmer Rouge is believed to have been responsible for the deaths of 1.7 million Cambodians while it held power from 1975-79, through execution, starvation and inadequate medical care as it sought to herd virtually the entire population into vast rural communes.