Former opposition leader Sam Rainsy has argued that video footage from a Phnom Penh gas station where analyst Kem Ley was murdered almost a year ago may absolve him of a “wrongful conviction” for defamation, according to new documents filed at a US court.

On July 10 last year, Ley was shot dead at a Caltex petrol station, which is owned by California-based gas giant Chevron. In March, Rainsy was found guilty in absentia of defaming Prime Minister Hun Sen for saying Ley’s killing was “state-sponsored terrorism”. The latest development in the search for footage – which Chevron has repeatedly said it no longer has as it was handed over to the authorities – saw the district court in Northern California accept two new legal briefs on Friday.

The footage and information Rainsy seeks will be presented to the Appeal Court in Phnom Penh to “reverse his wrongful conviction” and to “reveal whether there was government involvement” in Ley’s death, or “in any subsequent cover-up of official involvement in the crime”.

“[I]nformation or communications about the nature of the video or other digital footage . . . at the gas station may shed light on why the footage the police presented at the murder trial was incomplete and largely unintelligible,” Rainsy’s brief said.

“Materials that contradict the government’s prosecution narrative and undermine the footage it chose to present are themselves circumstantial evidence of government involvement in the crime.”

Rainsy, the brief continued, was “entitled to put exculpatory evidence into the record” regardless of “whether the court is realistically likely to give the evidence much, if any, weight”.

Ruling party spokesman Sok Eysan yesterday accused Rainsy of political pot-stirring and rebuked international interference in Cambodian courts.

“He makes anger and revenge against his political opponent Prime Minister Hun Sen,” he said. “If the international court does follow Sam Rainsy’s request, it means this court is crazy.”

Disputing the implication that the filings were a political stunt, Rainsy responded, “If anything was political it was the very assassination of Kem Ley.”

Chevron, which sought to quash the motion for discovery in March, now has until July 13 to lodge a response. “Chevron Corporation has sought to work with the Applicants on a cooperative basis for several months, and continues to seek a resolution of this issue outside the court,” spokesman Cameron Van Ast said yesterday.