Taiwanese prosecutors have charged four private investigators for taking Hong Kong money to spy on a sitting lawmaker and his family — a case being treated as hostile foreign interference.

• Four investigators were paid the equivalent of about NT$360,000 by two Hong Kong men to follow ruling-party legislator Puma Shen around the clock.
• When tailing him on foot failed because of his bodyguard, the team hid a tiny camera under a scooter seat outside his Taipei home and watched his door for weeks.
• Footage of Shen, his wife and daughter was passed up the chain over Telegram and sent on to the Hong Kong clients.
• Prosecutors want a year and a half in prison for the ringleader, saying he knowingly handed personal data to a hostile foreign power for money.
• The two Hong Kong men have already fled Taiwan and are now wanted.

Outlook: The case goes to court in Taipei, and expect more scrutiny of Taiwan's lightly regulated private-investigation industry as a channel for Chinese intelligence gathering.