A former Marine accused of assassinating a former lawmaker in Bangkok said he acted out of “gratitude,” police say.

A Thai man accused of killing a former Cambodian opposition lawmaker in Bangkok said he committed the crime to repay someone who helped him during a difficult period in his life, police told AFP.

Ekkalak Paenoi admitted to the crime on Saturday in a live video after being charged with premeditated murder and possession of a weapon without a licence. On Monday, a Thai court approved Ekalak’s detention for 12 days.

Lim Kimya, a former lawmaker for the defunct Cambodian National Rescue Party, was shot dead on Tuesday by a motorcyclist while arriving in Bangkok on a bus from Cambodia with his French wife.

Cambodian opposition figures accused the country’s powerful former leader Hun Sen of ordering the shooting, although a government spokesman denied official involvement.

Ekalak, who Thai media say is a former Marine, was arrested in Cambodia on Wednesday before being extradited to Thailand on Saturday.

“The shooter said he took this job to pay a debt of gratitude to someone who helped him during a difficult period after his dismissal from the Navy,” said Attaporn Wongsirprida, a senior police official in Bangkok.

Some Thai media reports said he was paid 60,000 baht ($1,700), but Attaporn told a local channel that Ikalak claimed he did not receive any money.

Attaporn refused to give further details when asked by Agence France-Presse.

Another senior police official said on Saturday that an arrest warrant had been issued for a Cambodian partner.

Dozens of Cambodian opposition activists have fled to Thailand in recent years to avoid alleged repression in their homeland. Some of them were arrested and deported to the country.

Hun Sen has ruled Cambodia with an iron fist for nearly four decades, with human rights groups accusing him of using the legal system to crush opposition to his rule.

He stepped down and handed power to his son, Hun Manet, in 2023, but is still seen as a major power in the kingdom.

On Tuesday, Hun Sen called for a new law describing anyone who tries to overthrow Hun Manet’s government as a “terrorist.”

The Cambodian National Rescue Party said in a statement that it was “deeply shocked and appalled by the brutal and inhumane assassination” and urged Thai authorities to conduct a comprehensive investigation to bring the perpetrators to justice.

The Cambodian National Rescue Party was expected to pose a strong challenge to former Prime Minister Hun Sen’s ruling Cambodian People’s Party in the 2018 general elections. But as part of a widespread crackdown on the opposition ahead of the election, the Supreme Court dissolved the party, and the ruling party subsequently won. All seats in the National Assembly.

Recent posts on Lim Kimya’s Facebook page were critical of the government, including how state funds were being unnecessarily spent on events that did not benefit the Cambodian people.

Under Hun Sen, who has been in power for nearly four decades, Cambodia has been widely criticized for human rights violations, including suppression of freedom of expression and association. He was succeeded in August 2023 by his US-educated son, Hun Manet, but there were few signs of political liberalization.

Phil Robertson, director of Human Rights and Action Advocates in Asia, said the shooting “bears all the hallmarks of a political assassination, and appears to represent a significant escalation in the use of transnational repression in Bangkok” to intimidate opposition to the ruling government.

The Associated Press contributed to this report.