Updated

U.S. Capitol Police are still investigating after House Democrats accused their colleagues of aiding Jan. 6 rioters by providing them with tours of the U.S. Capitol, Capitol Police confirmed to Fox News on Thursday.

"It's a fully loaded charge to accuse a different member of of an act of treachery of that sort, even if it's speculative. So I hope and expect that everyone who reviews what happened will take a very close look at that," former Senate Sergeant at Arms Drew Willison told Fox News.

"I really want to believe that no members were giving tours to rioters or allowing reconnaissance or anything like that," Willison continued. "There's been very little evidence of it over time. And it's sort of a horrifying thought that anyone would have that little respect for this institution that they worked so hard to get elected to."

A Capitol Police spokesperson did not say whether Capitol Police are leading the investigation.

BOEBERT BLASTS COHEN FOR 'IRRESPONSIBLE' CLAIM SHE LED CAPITOL TOUR BEFORE RIOT

Last week, House Democrats requested an immediate probe into "suspicious behavior" and access they claimed was given to visitors at the U.S. Capitol before the riot. Thirty-four lawmakers, led by Rep. Mikie Sherrill, D-N.J., who first went public with the "reconnaissance" tour claims, urged the Capitol Police and the acting House and Senate sergeants-at-arms to look into the matter in a letter

A man holds a Confederate flag outside the Senate Chamber during a protest after breaching the U.S. Capitol in Washington, D.C., Jan. 6, 2021. (SAUL LOEB/AFP via Getty Images) (Getty Images)

"The visitors encountered by some of the Members of Congress on this letter appeared to be associated with the rally at the White House the following day," the lawmakers wrote. "Members of the group that attacked the Capitol seemed to have an unusually detailed knowledge of the layout of the Capitol Complex. The presence of these groups within the Capitol Complex was indeed suspicious."

The letter does not name any members or staff who may have led the alleged "reconnaissance" tours, as Sherrill described them, or give more detail on why the visitors appeared suspicious.

"I also intend to see that those members of Congress who abetted him, those members of Congress who had groups coming through the Capitol that I saw on Jan. 5 for reconnaissance for the next day. Those members of Congress who incited the violent crowd. Those members of Congress that attempted to help our president undermine our democracy, I'm going see that they're held accountable," Sherrill said last week.

Rep. Steve Cohen, D-Tenn., named names during a CNN interview this week. He is not one of the letter's original signatories.

REP. LAUREN BOEBERT SAYS SHE'S RECEIVED DEATH THREATS OVER PERCEIVED SUGGESTION SHE HAD HELPED RIOTERS

"Only thing that I've seen, Congressman [John] Yarmuth refreshed my recollection yesterday, we saw Boebert taking a group of people for a tour sometime after [Jan. 3] and before [Jan. 6]," Cohen told CNN on Monday. "And she had a large group with her. Now whether they were people that were involved in the insurrection or not, I do not know. ... But it is pretty clear that her team is the team – she's not on the home team. She was with the visitors."

Rep. Lauren Boebert, R-Colo., blasted Cohen for the suggestion.

Republican Lauren Boebert, the then-candidate for the US House of Representatives seat in Colorado's 3rd Congressional District, addresses supporters during a campaign rally in Colona, Colo., on Oct. 10, 2020. (JASON CONNOLLY/AFP via Getty Images)

"During your interview on CNN today, you made false, slanderous statements that have threatened the safety of my family, my staff and me," Boebert wrote in a letter to Cohen. "It's unfortunate that you have connected my family being in D.C. for my swearing-in with the Capitol riots ... I have never given a tour of the U.S. Capitol to any outside group."

"As I previously stated, I brought my family to the Capitol on Jan. 2 for a tour and on the 3rd for pictures to commemorate the day I was sworn in as a member of the U.S. Congress," Boebert continued. "Again, the only people I have ever had in the Capitol with me during the 117th Congress are my young children, husband, mom, aunt and uncle."

Rep. Kim Schrier, D-Wash., who did not sign the letter, told Cheddar’s J.D. Durkin that protesters who entered the Capitol seemed to have inside knowledge of the Capitol building.

"The perpetrators, terrorists were able to find locations in the Capitol that I probably could not find," she said last week.

"The fact that there were any tours going on in a Capitol during a COVID pandemic when nobody is allowed unless they are personally escorted in by a member of Congress," she said, "suggests that if there was insider knowledge, that some of my colleagues may have been co-conspirators."

Some Republican members of Congress who have been staunch allies of former President Trump pushed back on Democrats' claims.

Rep. Mo Brooks, R-Ala., caught heat for speaking at the "Save America" rally in Washington, D.C., on Jan. 6, but his office told Fox News he hasn't given a tour since last year.

"Congressman Brooks has not conducted any tours of the Capitol since Capitol access was severely restricted in Winter/Spring 2020 timeframe due to COVID-19 and regular Capitol tours were discontinued," a spokesman for Brooks told Fox News.

Fox News' inquiries to the House and Senate sergeants-at-arms were not immediately returned.

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Fox News' David Aaro, Chad Pergram and Ronn Blitzer contributed to this report.