A Hong Kong court found former Apple Daily publisher Jimmy Lai guilty Monday, more than five years after he was first arrested amid a crackdown on the Chinese territory’s opposition movement.

Sentencing will take place at a later date, with the maximum punishment being life in prison. Mr. Lai’s family has warned even a far shorter sentence could see the 78-year-old die behind bars, given his advanced age and worsening health after five years in detention, much of it spent in solitary confinement.

There was a heavy police presence outside the West Kowloon Law Courts ahead of the verdict, where hundreds had queued to get one of the limited number of public seats inside court. The hearing was attended by diplomats from Britain, Canada and the European Union, who have been a steady presence throughout the trial of Mr. Lai, a British citizen.

A long-standing critic of China and booster of Hong Kong’s pro-democracy movement, Mr. Lai was arrested in 2020 amid a crackdown that followed months of anti-government protests the year before. He was charged under a national security law imposed on Hong Kong by Beijing, accused of sedition and colluding with foreign forces to undermine Chinese rule in the territory.