Veteran Cambodian opposition figure Sam Rainsy went on trial in France on Thursday in defamation cases brought against him by the prime minister and a top police official of his home country.
The France-based Rainsy, 73, is accused in relation to two separate complaints filed by Cambodian Prime Minister Hun Sen and his son-in-law and deputy national police chief, Dy Vichea, over Facebook posts dating back to 2019.
Hun Sen contests Rainsy's allegation that he was behind the 2008 death in a helicopter crash of national police chief Hok Lundy, who was Dy Vichea's father.
"Hun Sen killed Hok Lundy using a bomb placed inside his helicopter," Rainsy claimed on Facebook.
The leader of Cambodia's government "decided to murder Hok Lundy because he knew too much about Hun Sen's misdeeds", he added.
Dy Vichea has brought a second case against Rainsy over another Facebook post.
The hearing was expected to last just the single day, with judges then retiring to issue a verdict within weeks.
Entering the court, Rainsy told AFP that he expected "true justice" from France.
He told the court in French that Cambodia was currently a country with "no freedom of expression, where all those who want to tell the truth end up dead, in prison or in exile".
"I would like to help put an end to this culture of violence and impunity," he added, describing "Facebook as "my only window of expression".
But Luc Brossollet, a lawyer representing both top Cambodian officials, argued that the allegations on Facebook were defamatory.
"Whether you are an opponent or not, there is a certain line that you cannot cross and that is the one of the truth," he said.
"The things that form the factual basis of Sam Rainsy's accusations are hopelessly empty and grotesque and do not constitute evidence of the serious accusations we are examining," he said.
But defence lawyer Jessica Finelle told AFP that judges ought to "recognise that it is in the public interest for Sam Rainsy to denounce crimes committed by Hun Sen within a dictatorship".