Why is Trump visibly shaken as the Capitol attack investigation gets closer to its conclusion?

According to sources familiar with the situation, Donald Trump is becoming increasingly agitated by the House Select Committee investigating the Capitol attack, and he appears concerned that he might be implicated in the sprawling inquiry into the insurrection even as he protests his innocence.

In recent weeks, the former president has become more outspoken about the investigation, asking why his former White House chief of staff, Mark Meadows, shared so much information about 6 January with the select committee, and why dozens of other aides have also cooperated.

Trump has also been frustrated by aides invoking the Fifth Amendment in depositions, saying associates that it makes them appear weak and complicit in a crime, and considers them foolish for not following the lead of his former strategist Steve Bannon and simply ignoring the subpoenas.

When Trump sees new developments in the Capitol attack investigation on television, he starts cursing the negative coverage and bemoans the fact that the House minority leader, Kevin McCarthy, was too inept to appoint Republicans to the committee to defend him.

The former president’s anger is similar to the expletives he used to direct at the Russia investigation and the special counsel investigation when he was in the White House. However, the rapidly accelerating investigation into whether Trump and top aides unlawfully conspired to obstruct the certification of Joe Biden’s victory at the joint session on January 6 appears to be deeply disturbed him.

The portrait that emerges from interviews with multiple sources close to Trump, including current and former aides, suggests a former president unmoored and backed into a corner by the committee’s investigation’s rapid escalation in intensity.

Trump’s spokesperson did not respond to requests for comment.

But, as Trump struggles to shield himself from the select committee, with public hearings planned for next year and the Justice Department reportedly checking up on the investigation, the road ahead is only likely to become more treacherous.

Even as he maintains that he did nothing wrong in discussing ways to overturn the 2020 election and encouraging supporters to march on the Capitol, the former president is acutely aware of the potential of legal consequences. He has expressed concern to associates about repeated defeats in court as he seeks to prevent the select committee from obtaining some of the most sensitive White House documents from the National Archives on the grounds of executive privilege on January 6th.

The reality is that the committee appears to be gathering new evidence about Trump’s involvement in the Capitol attack with each passing day, which could lead to recommendations for new election laws – but also prosecutions.

“I think that the justice department will keep a keen eye on what evidence the committee has accumulated, as well as looking out for witnesses for a potential case,” said Ryan Goodman, a former special counsel at the Department of Defense now a law professor at New York University.

“One of the outcomes of the committee’s work and the public hearings will be to demonstrate individuals who might be wanting to come forward as witnesses and that’s got to be very important to justice department prosecutors,” Goodman said.

House investigators are expected to interview more than 300 Trump administration officials and Trump political operatives as part of a process that has yielded 30,000 documents and 250 tips through the select committee’s tip line.

The flurry of recent revelations – such as Meadows’ connection to a PowerPoint outlining how Trump could stage a coup, as first reported by the Guardian – raises the possibility that the select committee is rapidly heading towards an incriminating conclusion.

Trump’s associates insist they are not concerned, at least for the time being, because the select committee has yet to obtain materials protected by executive privilege, either through Meadows or the National Archives, that could bring Trump personally into disrepute.

In that regard, the former president’s supporters are correct – the committee does not have messages showing Trump directing an attack on the Capitol, according to one source – Trump has also promised to take the National Archives case to the Supreme Court.

But no one outside the select committee, which is working quietly from a glass office on Capitol Hill with boarded-up windows and electronically secured doors, knows what it has discovered or whether the inquiry will result in a criminal referral.

Meadows’ material alone depicts an alarming strategy to stop Biden’s certification on January 6, involving nearly the entire federal government and lieutenants operating from the Willard Hotel in Washington.

One member on the select committee described the events around 6 January as showing a coalescence of multiple strategies: “There was a DoJ strategy, a state legislative strategy, a state election official strategy, the vice-president strategy. And there was the insurrection strategy.”

Meadows’ text messages on his personal phone implicate Trump’s eldest son, Don Jr., as well as Republican members of Congress. If the White House knew election fraud claims were false but still used them to block Biden’s certification, the texts Meadows turned over to the committee could be used as evidence of criminal obstruction to stop a congressional proceeding by an astute prosecutor.

While Meadows never testified about the communications, a number of top Trump officials, including former acting national security adviser Keith Kellogg and Pence’s former chief of staff Marc Short, have agreed to cooperate with House investigators.

The trouble for Trump – and a source of his frustration, according to sources – is his inability to use the executive branch’s vast power to influence the course of the investigation while out of office.

The failure of strategies he hoped would stymie the committee – such as ordering aides to defy subpoenas or launching legal challenges to delay the release of White House records – has been jarring for Trump.

“I think what he’s finding is that as the ex-president, he has a lot less authority than he did as president. But his playbook doesn’t work if he’s not president,” said Daniel Goldman, former lead counsel in the first House impeachment inquiry into Trump.

In light of the dwindling legal avenues for undermining the investigation, Trump has returned to launching attacks on the select committee via an emailed statement, stewing over his predicament and what he sees as an investigation designed purely to hurt or kill him politically.

“The Unselect Committee itself is Rigged, stacked with Never Trumpers, Republican enemies, and two disgraced RINOs, Cheney and Kinzinger, who couldn’t get elected ‘dog catcher’ in their districts,” Trump vented last month.

In private, Trump is said to have reserved the brunt of his dissatisfaction for Meadows, furious with his former White House chief of staff for sharing sensitive communications on top of all the unflattering details about Trump in his book this month.

Trump’s associates, on the other hand, have focused on the select committee’s legitimacy and composition, arguing that the fact that the House Speaker, Nancy Pelosi, appointed both Republican members reduce the investigation to a partisan political endeavor.

They also argue that none of the recent revelations – such as the Guardian’s reporting on Trump’s call to the Willard Hotel, during which he pressed operatives to prevent Biden’s certification from taking place – comprise criminal wrongdoing.

In the meantime, Trump has little choice but to wait patiently for the committee’s report.

“The justice department seems to be more reactive than proactive,” Goodman said. “They might be waiting for the committee to wrap up its work to make criminal referrals.”