In the Capitol’s Shadow, the Jan. 6 Panel Quietly Ramps Up Its Inquiry

Soon, the inquiry will enter a new phase, with plans to hold a series of public hearings in early spring to lay out some of its findings. Those will feature, among other topics, state election officials testifying to the security and accuracy of the 2020 election. A final report will be issued, “obviously before the November elections,” Mr. Thompson said.

For now, the O’Neill building is the main hub of activity, where, depending on the day, the political operative Roger J. Stone Jr., a longtime adviser to Mr. Trump, might appear outside flashing his signature Nixon-style “V for victory” sign to a sea of news cameras; or a lawyer for a Jan. 6 rally planner might arrive promoting a “treasure trove” of documents he says will leave senior Trump allies “quivering in their boots.” Reporters often dart up and down hallways trying to catch up to the various witnesses leaving the interview rooms.

Inside, investigators and members of the nine-person committee are questioning witnesses, with the lawmakers — juggling busy schedules of floor votes and other congressional hearings — often bouncing between the interviews on a direct TV feed.

“We are participating in the depositions and interviews regularly, and these are quite lengthy,” said Representative Elaine Luria, Democrat of Virginia and a member of the committee. “Even with other work that we have to do throughout the day, members are joining regularly to ask questions about specific areas.”

The so-called green team is following the money trail connected to Mr. Trump’s efforts to promote the baseless assertion that he was the rightful winner of the election, including whether any groups defrauded contributors with false statements about widespread election fraud.

The gold team is scrutinizing any plans Mr. Trump made with members of Congress to try to overturn the election and his pressure campaign on local, state and Justice Department officials to try to keep himself in power.

Domestic violent extremist groups, such as the QAnon movement and the militia groups, the Oath Keepers and the Proud Boys, are the focus of the purple team. A fourth, the red team, is digging into the Jan. 6 rally planners and the Stop the Steal movement.