The House select committee investigating the Capitol attack is likely to make a decision this week on whether to charge Mark Meadows, Donald Trump's final White House chief of staff, with criminal contempt of Congress, a key panel member said.
"I think we will probably make a decision this week on our course of conduct with that particular witness and maybe others," Adam Schiff, a California Democrat and chair of the House intelligence committee, told CNN's State of the Union.
Schiff also said he was concerned about the Department of Justice, for a perceived lack of interest in investigating Trump's own actions, including asking officials in Georgia to "find" votes which would overturn his defeat by Joe Biden.
The 6 January committee is investigating the attack on the Capitol by Trump supporters who the then president told to "fight like hell" to overturn his defeat.
Trump was impeached with support from 10 House Republicans but acquitted in his Senate trial when only seven GOP senators defected. The select committee contains only two Republicans, Adam Kinzinger and Liz Cheney, who broke with Trump over 6 January.
"We tried to hold the former president accountable through impeachment," Schiff said. "That's the remedy that we have in Congress. We are now trying to expose the full facts of the former president's misconduct as well as those around him."
Asked about Meadows, Schiff said: "I can't go into you know, communications that we're having or haven't had with particular witnesses.
"But we are moving with alacrity with anyone who obstructs the committee, and that was really the case with Mr Bannon, it would be the case with Mr Meadows and Mr Clark or any others."
Steve Bannon, Trump's former campaign chair and White House strategist, pleaded not guilty to a charge of criminal contempt, the first pursued by Congress and the DoJ since 1982. Facing a fine and jail time, on Thursday Bannon filed a request that all documents in his case be made public.
Like Bannon and Meadows, Jeffrey Clark, a former Department of Justice official, has refused to co-operate with the House committee. Lawyers for Trump and his allies have claimed executive privilege, the doctrine which deals with the confidentiality of communications between a president and his aides. Many experts say executive privilege does not apply to former presidents. The Biden White House has waived it.
"It varies witness to witness," Schiff said, "but we discuss as a committee and with our legal counsel what's the appropriate step to make sure the American people get the information. We intend to hold public hearings again soon to bring the public along with us and show what we're learning in real time. But we're going to make these decisions very soon."
Schiff said he could not "go into the evidence that we have gathered" about Trump's role in the events of 6 January, around which five people died and on which the vice-president, Mike Pence, was hidden from a mob which chanted for his hanging.
"I think among the most important questions that we're investigating," Schiff said, "is the complete role of the former president.
"That is, what did he know in advance about propensity for violence that day? Was this essentially the back-up plan for the failed [election] litigation around the country? Was this something that was anticipated? How was it funded, whether the funders know about what was likely to happen that day? And what was the president's response as the attack was going on, as his own vice-president was being threatened?
"I think among the most, the broadest category of unknowns are those surrounding the former president. And we are determined to get answers."
Schiff was also asked about suggestions, including from Amit Mehta, a federal judge overseeing cases against Capitol rioters - nearly 700 of whom have been charged - that Trump might seem to be being let off the hook by the Department of Justice.
Schiff said: "I am concerned that there does not appear to be an investigation, unless it's being done very quietly by the justice department of … the former president on the phone with the Georgia secretary of state, asking him to find, really demanding he find 11,780 votes that don't exist, the precise number he would need to overturn Joe Biden's victory in that state.
"I think if you or I were on that call and reported we'd be under investigation [or] indictment by now for a criminal effort to defraud the people in Georgia and the people the country.
"So that specifically I'm concerned about."