James To was growing uneasy. When the veteran Hong Kong Democratic Party lawmaker looked in his rearview mirror, two silver Mercedes Benz saloons kept appearing behind his gray Volvo sedan.

For almost a week, one or the other was behind him on his daily commute. When he arrived at the Legislative Council building, the following car would park nearby and wait, sometimes for hours. With his suspicion hardening, on Aug. 11 To complained to the police, reporting the registration numbers of the two Mercedes in his detailed statement.

The next morning he pulled out of his home in the largely working-class neighborhood of North Point on Hong Kong island and headed to work. At the bottom of the street outside his building, he glanced in the mirror to see an unmarked car pull sharply into the path of a silver Mercedes behind him. Several men got out of the unmarked car. He kept driving, assuming the police had moved fast to intercept his tail.