Former Thai Prime Minister Thaksin Shinawatra has begun testifying in a royal defamation trial that could see him jailed for up to 15 years. The case centres on remarks he made to South Korean media over a decade ago, with the closed-door proceedings expected to continue for several days, according to Al Jazeera.

The trial comes just weeks after his daughter, Paetongtarn Shinawatra, was suspended as prime minister pending an ethics probe over a leaked phone call linked to a deadly border clash with Cambodia. The scandal has weakened the ruling Pheu Thai-led coalition, now clinging to a slim majority.

Thaksin, 75, returned from exile last year after a military coup ousted him in 2006. He was sentenced to eight years for corruption, later reduced to one following a royal pardon.

Supporters gathered at the court as his lawyer said Thaksin remains composed. The trial and Paetongtarn’s suspension mark a sharp decline in the Shinawatra family’s political fortunes, Al Jazeera reported.