He was among seven convicted defendants who appeared in court for their roles in the plot to plant two bombs and shoot officers along a rally route on Dec. 8, 2019, at a time when accusations of police brutality in handling protesters were widespread.
Judge Judianna Barnes said the plan was vicious and was a declaration of war on society.
The seven are not well-known activists in the semi-autonomous Chinese city’s pro-democracy movement, but their case has drawn attention because the United Nations (Anti-Terrorism Measures) Ordinance was invoked.
Hong Kong enacted the law to implement a U.N. Security Council resolution passed after the Sept. 11, 2001, attacks in the United States.
According to local media, prosecutors said most of the defendants in the case were members of two groups — one led by Ng and another called “Dragon-Slaying Brigade." The prosecution said members of the brigade planned to lure police officers onto an area where bombs would be detonated and a sniper would target them.
Wong Chun-keung, leader of the brigade, was sentenced to more than 13 years. Five other defendants received prison terms ranging from nearly six years to 12 years.
In August, six other defendants, who had pleaded not guilty, were acquitted by a panel of jurors.
Steve Li, chief superintendent for the police's national security department, said he would study the judgment and consider whether to appeal some sentencing decisions. He also criticized those convicted as deranged.
The 2019 protests marked the most concerted challenge to the Hong Kong government since the former British colony returned to Chinese rule in 1997.
Following the protests, more than 10,000 people have been arrested in connection with the often-violent social unrest sparked by a now-withdrawn extradition bill, which would have allowed suspects in Hong Kong to be sent to mainland China.