Prime Minister Hun Sen is preparing to launch a legal case against an opposition senator for suggesting he was behind the murder of political analyst Kem Ley, according to a government lawyer and the premier’s own comments to CPP-friendly local media.

Ky Tech, an attorney who represents top Cambodian People’s Party officials, said a complaint would be filed against Sam Rainsy Party Senator Thak Lany today or Tuesday for remarks she made while addressing supporters in Ratanakkiri province on Friday.

According to video posted to Facebook, Lany – who has told local radio that the footage was edited – made the accusation while suggesting that Ley’s murder was connected to his analysis of a Global Witness report that highlighted the premier’s family’s vast business holdings.

“And now [we] don’t know what Hun Sen thinks anymore, [all of a sudden] to go shoot Mr Kem Ley, Kem Ley the political analyst,” Lany appears to say. In an article published on Friday night, media outlet Fresh News, which is routinely used to disseminate official government documents, reported that Hun Sen had told reporters in a closed-door meeting that “a complaint will be made soon”.

According to the outlet, the prime minister also added: “For this senator, it will not be difficult to sue and vote to strip [her] immunity, because senators of the Cambodian People’s Party have over two-thirds of the vote.”

The Cambodian constitution states that “no Senator shall be prosecuted, detained or arrested because of opinions expressed in the exercise of his/her duties”, but the charter allows two-thirds of senators to strip a colleague’s immunity.

Tech would not say whether the complaint would accuse the politician of defamation or another crime, because such a decision rested with the prosecutor. “When we lodge a complaint, we must write what the facts have caused. The prosecutor examines this fault and [decides] what offence must be used,” Tech said.

Lany was unreachable yesterday. However, in an interview with Radio Free Asia on Saturday, she dismissed the accusation, saying her voice had been edited and she did not accuse the premier of killing Ley, who was shot dead while he drank coffee in a Phnom Penh petrol station on July 10. Fellow SRP Senator Teav Vannol yesterday said he was unaware of the threatened case but said the party would provide a lawyer for the senator, whose whereabouts he said he did not know.

Though the purported remarks may be among the first attributed to a political figure directly linking Hun Sen to the killing, accusations of government involvement arose almost immediately after Ley’s death, including by opposition leader Sam Rainsy.

Police have laid a murder charge against former soldier and ex-monk Oeut Ang, 44, who was arrested about 1.5 kilometres from the petrol station after fleeing on foot.

Soon after his capture, authorities released a video confession in which Ang gives his name as “Choub Samlab”, which translates in English to “meet to kill”, and says he killed Ley over a debt. However, many have cast doubt on that motive, including the suspect’s own family and the authorities.

Contacted yesterday to discuss new video footage that shows Ang just before and during his arrest on Sothearos Boulevard, National Police spokesman Kirt Chantharith said that the suspect was “hired” as part of a “plan” but did not elaborate.

The footage shows Ang jogging along the boulevard, opposite the Sofitel hotel, before a man wearing a white helmet and riding a police motorbike pulls up beside him. Ang first attempts to get on the bike, though can then be seen running north again away from the driver.

In the next clip, Ang tosses his gun near an armed military police officer before running and getting on the back of what appears to be the same police motorbike, this time further down the road. Another clip shows several people beat the suspect while he is on the back of the motorbike, which eventually drives off.

Calling for people to post any videos linked to the crime, Chantharith yesterday dismissed any suggestion of official collusion in the murder, saying officers “tried their best to find him”.