There were those who showed up to hear President Trump speak. They numbered around 200,000 or so. Most of them marched peacefully. Most had no idea that the Capital had been breached by angry protesters.

A much smaller group had breached the Capital building, sending lawmakers into hiding. Most of them where Trump supporters, but not all. 

John Sullivan, an admitted left wing activist, can allegedly be heard egging on right wing protesters as they enter the capital. The audio can be heard and he can be seen in video he provided to the FBI, according to a federal criminal complaint. John Sullivan shared the video to his YouTube and Twitter accounts under the pseudonym Jayden X.

As protesters were climbing over a wall by the Capitol entrance, he allegedly can be heard yelling, "You guys are f------ savage. Let’s go!"

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On the video Mr. Sullivan, allegedly, can be heard yelling to Trump supporters "We got to get this s--- burned," and "it’s our house m------------," according to an affidavit signed by FBI Special Agent Matthew Foulger.

Mr. Sullivan was in federal court on Thursday in Washington after being arrested by the FBI. He remains in custody.

But was he just there to "document" what was going on as he claims?

Rolling Stone published an interview with Mr. Sullivan on Wednesday where Sullivan claims that he was putting on an act to build rapport with the protesters.

"I had to relate to these people, and build trust in the short amount of time I had there to get where I need to go," he told the magazine. "To the front of the crowd to see the dynamic between the police and the protesters, because nobody wants to see the backs of people’s heads from a far-off distance."

Sullivan is the founder of a small Utah-based group called Insurgence USA. He told Fox News he’d entered the besieged Capitol to "document" what was going on.

While he has denied ties to the left wing fascist Group Antifa, the group he founded, Insurgence USA, had advertised an event called "Kick These Fascists out of DC" on Wednesday around the same time as a pro-Trump.

PHOTOS: Scene at U.S. Capitol shows chaos and violence