Back in 2002:
On April 20, 2002, FBI agents in plain clothes targeted the protesters because of their black garments, apparently the definitive anarchist fashion choice. Then, the people were separated and asked about their political and religious views as well as the names of their friends and associates. Some of the interrogations were videotaped — not the best way to keep quasi-legal procedures a secret. The police documents surfaced thanks to a lawsuit brought by the protesters claiming their civil rights were violated.
For over three years MPD and the FBI have denied any such incident took place. District officials said they had no record of the interrogation and that no FBI officials were present when the demonstrators were arrested for trespassing.