A politician was shot dead in Bangkok. Did another country do it?

It had all the hallmarks of a cold-blooded, professional assassination.

Next to a well-known temple in Bangkok's historic royal quarter a man is seen on a security camera video parking his motorbike, removing his helmet, so that his face was clearly visible, and walking calmly across the road.

A few minutes later shots are heard. Another man falls to the ground.

The assassin walks quickly back to his motorbike, appearing to throw something away as he does, and drives off.

The victim was Lim Kimya, a 73-year-old former parliamentarian from the main Cambodian opposition party, the CNRP, which was banned in 2017. He had been hit in the chest by two bullets, according to the Thai police. He had just arrived in Bangkok with his wife on a bus from Cambodia.

A police officer attempted to resuscitate him, but he was pronounced dead at the scene.

"He was courageous, with an independent mind," Monovithya Kem, daughter of the CNRP leader Kem Sokha, told the BBC.

"No-one but the Cambodian state would have wanted to kill him."

Lim Kimya had dual Cambodian and French nationality, but chose to stay in Cambodia even after his party was outlawed. The CNRP – Cambodia National Rescue Party – was an amalgamation of two earlier opposition parties, and in 2013 came close to defeating the party of Hun Sen, the self-styled "strongman" who ruled Cambodia for nearly 40 years before handing over to his son Hun Manet in 2023.

After his close call in the 2013 election Hun Sen accused the CNRP of treason, shutting it down and subjecting its members to legal and other forms of harassment. In 2023 Kem Sokha, who had already spent six years under house arrest, was sentenced to 27 years in prison.

High-level political assassinations, though not unknown, are relatively rare in Cambodia; in 2016 a popular critic of Hun Sen, Kem Ley, was gunned down in Phnom Penh and in 2012 environmental activist Chut Wutty was also murdered.

From the security camera video the Thai police have already identified Lim Kimya's killer as an ex-Thai navy officer, now working as a motorbike taxi driver. Finding him should not be difficult.

Whether the killing is fully investigated, though, is another matter.