When Samuel Bickett, a former Bank of America compliance director, saw a man with a retractable baton confronting a teenager in a subway station in Hong Kong in 2019, he assumed he had stumbled on an assault. He immediately tried to help the kid by trying to grab the baton, he says. What he didn’t know was that the man was Senior Constable Yu Shu-sang, an undercover officer, and the younger man had just skipped his fare at the nearby subway station.

Bickett, 37, who was convicted of assault and denied bail in June, has now been sentenced to four months and two weeks in a Hong Kong jail. A video of the incident shows another commuter asking Yu if he was a “po-po” or what pro-democracy protesters called police officers, which Yu first denied and then admitted to.

At the time, pro-democracy protests were in full swing in Hong Kong and anti-police sentiment was high, so officers working undercover were often vulnerable. Hong Kong had introduced an extradition bill that was later removed, but which would have meant that Hong Kong residents could be prosecuted in China.

Bickett argued that he had no idea Yu was an officer and that he just thought he was a man threatening someone younger unprovoked. But the judge, Magistrate Arthur Lam Hei-wei, disagreed and said he understood why Yu would first deny being a cop, especially under the circumstances in which he was asked if he was a “po-po.”

Yu claimed that Bickett knelt on his chest and punched his face, which, from the video, seems an exaggeration of the events.