A growing chorus of international observers and civil society groups are calling for an “independent” investigation into the murder of political commentator Kem Ley, saying any probe should be ring-fenced from potential government interference.

“This investigation should be conducted by an independent body with no ties to the government,” reads a statement issued by five UN rights experts yesterday, which referenced concerns that Ley’s death could be linked to his vocal criticism of the government.

Kingsley Abbott, senior regional legal adviser to the International Commission of Jurists, went a step further in emailed comments. Specifically calling for the possibility that “agents of the state” were involved in Ley’s death to be examined, he said the ideal investigative team would be “totally independent of the state”, given what he termed a history of politically motivated killings.

Abbott called on the government to appoint a special prosecutor or investigator from Cambodia, “A senior and experienced private lawyer, for example.” Otherwise, he said, the government should invite an international organisation, such as the UN, to form an investigative team.

However, if the government fails to cede control of the investigation, Abbott said the alternative was for those running it to be as transparent as possible. This would include regular updates and the ability for external observers to ask questions of the team.

“For example,” he wrote. “Why an autopsy has not been conducted? Has the team sought international expertise and if not, why not? Is a detailed analysis of the suspect’s phone and financial records underway?”

Echoing Abbott’s concerns was Nicolas Agostini, the Worldwide Movement for Human Rights’ representative to the UN.

“As there are grounds to believe that this killing is politically motivated, the chain of command should be investigated up to the highest political level,” Agostini wrote in an email.

“As a matter of principle, we will continue to call for an investigation that is free from political interference and in line with international standards,” he wrote, though he noted this would be unprecedented for an assault on a public figure in Cambodia.

The Cambodia National Rescue Party piled in, issuing a statement. “National and international opinion does not have confidence that the [investigating] authorities have independence,” it read.

National Police spokesman Kirt Chantharith yesterday described calls for the investigation to be taken off the government’s hands as an assault on Cambodia’s sovereignty.

“[They] allege [we] are the Yuon’s slaves while they look for help from the sharp noses,” he said, using a term for Vietnamese considered derogatory by many and a slang term for Caucasian foreigners. “Does our country not know how to work?”