The House select committee is looking into reports of protesters who scope during the Capitol riot, and is asking Barry Loudermilk of Georgia if he led a tour of the Capitol the day before the riot.
The Republicans on the Committee on House Administration claimed to have reviewed security video footage of Loudermilk.
The letter from the Select Committee's chairman and vice chairman said that the review of evidence directly contradicted the denial.
We believe you have information regarding a tour you led through parts of the Capitol complex on January 5, 2021, according to the letter.
After weeks of false claims by former President Donald Trump that he was cheated out of re-election because of widespread ballot fraud, members of Congress urged law-enforcement officials to investigate reports of so-called "reconnaissance tours" of the Capitol.
Some individuals and groups are trying to gather information about the layout of the U.S. Capitol, as well as the House and Senate office buildings, in advance of the riot.
Loudermilk's spokesman did not respond to a request for comment on the letter.
The committee issued subpoenas for testimony from House Republican leader Kevin McCarthy and four other congressmen allied with Trump. The committee for fellow sitting members of Congress issued the first subpoenas.
Bill Barr, who was Trump's attorney general until he quit in December 2020 after refusing to endorse claims of widespread election fraud, is in discussions with the committee to be interviewed.
A spokesman for the committee didn't comment on the report immediately.
The joint session of Congress was disrupted by the riot.
Loudermillk, who compared Trump's first impeachment to the crucifixion of Jesus Christ, was among a minority of House members who voted to reject the Electoral College votes for Biden from Arizona and Pennsylvania.
The letter to him from the panel indicates investigators are still looking for leads related to the riot weeks before the committee will hold the first in a series of public hearings.
McCarthy and the four other Republicans who were issued subpoenas have not said if they will comply with the demands for their testimony.