Capitol Police and acting House Sergeant at Arms Timothy Blodgett are looking into reports that certain members of Congress may have hosted tours of the Capitol in the days leading up to the unprecedented breach of the building, a well-placed source familiar with the situation told Fox News.

Some Democratic members are calling for an investigation into allegations that certain Republican lawmakers hosted outings at the complex for people in town for Jan. 6 protests over the outcome of the 2020 presidential election. The Capitol complex has been closed to public tours for months because of restrictions related to the coronavirus pandemic, but members of Congress are still able to give private tours.

Steven D’Antuono, assistant director in charge at the FBI’s Washington field office, declined to comment on whether the FBI is looking into reports that certain congressional members may have somehow aided some of the rioters, but he did not rule out the possibility.

"This is a large puzzle and we're looking at every piece to put it together ... we will not leave anything unturned," D’Antuono said at a briefing.

Lawmakers on both sides of the aisle have demanded answers in recent days as to how protestors were able to enter the Capitol despite the security presence. In a letter to Capitol security officials earlier this week, Rep. Mikie Sherrill, D-NJ, called for an investigation into "suspicious behavior and access" given to Capitol visitors on Jan. 5, the day before the riot.

Members of Congress were forced to flee as the crowds breached both the House and Senate chambers. Earlier Friday, House Speaker Nancy Pelosi, whose office was vandalized during the riot, warned that any lawmaker found to have aided the violence could face charges.

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"If in fact it is found that members of Congress were accomplices to this insurrection, if they aided and abetted the crime, there may have to be actions taken beyond the Congress in terms of prosecutions," Pelosi said at a press conference.

Efforts to ramp up security have intensified ahead of President-elect Joe Biden’s inauguration on Jan. 20. FBI Director Christopher Wray said authorities had more than 100 arrests of individuals who participated in the riots since their investigation began.

Fox News’ Thomas Barrabi contributed to this report.