“No cops, no prisons, total abolition,” they chanted. Some of the activists, dressed in the trademark uniform of solid black clothing and masks that often signals a readiness to make trouble without being readily identifiable, smashed windows at the local Democratic Party headquarters.

The event — like others that had consumed the city since the murder of George Floyd by a police officer in Minneapolis in 2020 — included a variety of anarchists, antifascists, communists and racial justice activists. But there were others mingling in the crowd that day: plainclothes agents from the Federal Bureau of Investigation.