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Since last Wednesday's Capitol riot, the FBI has been sifting through tips, gathering evidence, and making arrests, and investigators have found that dozens of people on a terrorist watch list were in D.C. for pro-Trump events, The Washington Post reports.

People familiar with the matter told the Post many of these individuals are suspected white supremacists who were put on the FBI's Terrorist Screening Database due to their alarming behavior. This is separate from the "no-fly list" that is maintained by the government to keep terrorism suspects off airplanes, and can be accessed by different law enforcement officers, including state troopers and border agents.

The Post spoke with several current and former officials who said it isn't surprising these individuals went to the "Stop the Steal" rally, held immediately before the Capitol riot. President Trump urged his supporters to pressure lawmakers into overturning election results, and many saw this as the last time they could publicly oppose the certification of the Electoral College votes.

Prior to the rally, FBI agents spoke with several suspected extremists, asking them to stay away from D.C., and many did heed their advice, the Post reports. Dozens of people have been arrested in connection with the riot, but it's unclear how many are on the watch list.