HONG KONG (AP) — Jimmy Lai, the pro-democracy former Hong Kong media mogul and outspoken critic of Beijing, was convicted in a landmark national security trial in the city’s court on Monday, which could send him to prison for the rest of his life.

Three government-vetted judges found Lai, 78, guilty of conspiring with others to collude with foreign forces to endanger national security and conspiracy to publish seditious articles. He pleaded not guilty to all charges.

Lai was arrested in August 2020 under a Beijing-imposed national security law that was implemented following massive anti-government protests in 2019. Lai has spent five years in custody, much of it in solitary confinement, and appears to have grown more frail and thinner. He has also been convicted of several lesser offenses related to fraud allegations and his actions in 2019.

Lai’s trial, conducted without a jury, has been closely monitored by the U.S., Britain, the European Union and political observers as a barometer of media freedom and judicial independence in the former British colony, which returned to Chinese rule in 1997.

Reading from an 855-page verdict, Judge Esther Toh said that Lai had extended a “constant invitation” to the U.S. to help bring down the Chinese government with the excuse of helping Hong Kongers.

Lai’s lawyers admitted during the trial that he had called for sanctions before the law took effect, but insisted he dropped these calls to comply with the law.

But the judges ruled that Lai had never wavered in his intention to destabilize the ruling Chinese Communist Party, “continuing though in a less explicit way.”

Toh said the court was satisfied that Lai was the mastermind of the conspiracies and that Lai’s evidence was at times contradictory and unreliable. The judges ruled that the only reasonable inference from the evidence was that Lai’s only intent, both before and after the security law, was to seek the downfall of the ruling Communist Party even at the sacrifice of the people of China and Hong Kong.

“This was the ultimate aim of the conspiracies and secessionist publications,” they wrote.

Among the attendees were Lai’s wife and son, and Hong Kong’s Roman Catholic Cardinal Joseph Zen. Lai nodded to his family before being escorted out of the courtroom.

His verdict is also a test for Beijing’s diplomatic ties. U.S. President Donald Trump said he has raised the case with China, and U.K. Prime Minister Keir Starmer has said his government has made it a priority to secure the release of Lai, who is a British citizen.

The founder of the now-defunct pro-democracy newspaper Apple Daily will be sentenced on a later day.

The collusion charge carries a maximum penalty of life imprisonment. Hearings were set to begin Jan. 12 for Lai and other defendants in the case to argue for a shorter sentence.

The Apple Daily, a vocal critic of the Hong Kong government and Beijing, was forced to shut in 2021 after police raided its newsroom and arrested its senior journalists, with authorities freezing its assets.

During Lai’s 156-day trial, prosecutors accused him of conspiring with senior executives of Apple Daily and others to request foreign forces to impose sanctions or blockades and engage in other hostile activities against Hong Kong or China.

The prosecution also accused Lai of making such requests, highlighting his meetings with former U.S. Vice President Mike Pence and former Secretary of State Mike Pompeo in July 2019 at the height of the protests.

It also presented 161 publications, including Apple Daily articles, to the court as evidence, as well as social media posts and text messages.

Lai testified for 52 days in his own defense, arguing that he had not called for foreign sanctions after the sweeping security law was imposed in June 2020.

His legal team also argued for freedom of expression.

As the trial progressed, Lai’s health appeared to be deteriorating.

Lai’s lawyers in August told the court that he suffered from heart palpitations. After the verdict, lawyer, Robert Pang, said his client is in okay spirits as the legal team studies the verdict.

Before the verdict, his daughter Claire told The Associated Press that her father has become weaker and lost some of his nails and teeth. She also said he suffered from infections for months, along with constant back pain, diabetes, heart issues and high blood pressure.

“His spirit is strong but his body is failing,” she said.

Hong Kong’s government said no abnormalities were found during a medical examination that followed Lai’s complaint of heart problems. It added this month that the medical services provided to him were adequate.

Hong Kong leader John Lee said Lai harmed the fundamental interests of the country, calling his intentions malicious.

Steve Li, chief superintendent of Hong Kong police’s National Security Department, disputed claims of Lai’s worsening health outside the court building.

“Lai’s conviction is justice served,” he told reporters.

U.K. Foreign Secretary Yvette Cooper said on X that her country condemned the politically motivated prosecution that resulted in the guilty verdict, saying it would continue to call for his release.

In Beijing, Chinese Foreign Ministry spokesperson Guo Jiakun said China expressed firm opposition to the vilification of the city’s judiciary by “certain countries,” urging them to respect the city’s legal system.

Rights groups, including global media watchdog Reporters Without Borders and Amnesty International, criticized the verdict.

“It is not an individual who has been on trial — it is press freedom itself, and with this verdict that has been shattered,” said Reporters Without Borders’ director general Thibaut Bruttin.

But Hong Kong Secretary for Security Chris Tang said the verdict has nothing to do with press freedom.

Before sunrise, dozens of residents queued outside the court building to secure a courtroom seat.

Former Apple Daily employee Tammy Cheung arrived at 5 a.m., saying she wanted to know about Lai’s condition after reports of his health.

She said she felt the process was being rushed since the verdict date was announced only last Friday, but added, “I’m relieved that this case can at least conclude soon.”

Associated Press writer Chan Ho-him in Hong Kong contributed to this report.