Has America moved on from the unsavory events of January 6, 2021? Maybe, but not in the nation’s capital, where the House panel investigating the January 6 riot at the U.S. Capitol laid the blame firmly on President Trump Thursday night, saying the assault was hardly spontaneous but an “attempted coup” and a direct result of the defeated president’s effort to overturn the 2020 election.

With a never-before-seen 12-minute video of so-called extremist groups leading the assault and some compelling testimony from Mr. Trump’s most inner circle, the January 6 committee provided gripping detail in contending that Mr. Trump’s repeated lies about election fraud and his public effort to stop Joe Biden’s victory led to the attack, in their estimation imperiling American democracy.

“January 6 was the culmination of an attempted coup, a brazen attempt, as one rioter put it shortly after January 6, to overthrow the government,” Representative Bennie Thompson, chairman of the panel, said. “The violence was no accident.”  The hearing was deliberately timed for prime time to reach as many Americans as possible, though Washington may have missed the memo that large segments of the American population no longer turn to their television sets as a primary source of news as their parents might have done. 

The tenor of the hearings, if not all the testimony, might have struck some as heavily scripted. The highly charged hearings may not change Americans’ views on the Capitol attack, but the panel’s investigation is intended to stand as its public record. Ahead of this fall’s midterm elections, and with Mr. Trump considering another White House run, the committee’s final report aims to account for the most violent attack on the Capitol since 1814, and to ensure such an attack never happens again.

Mr. Thompson laid out the committee’s initial findings that Trump led a “sprawling, multi-step conspiracy aimed at overturning the presidential election,” and the panel’s vice chairwoman, Representative Elizabeth Cheney, called it a “sophisticated seven-part plan.”

Testimony showed Thursday how Mr. Trump desperately clung to his own false claims of election fraud, beckoning supporters to the Capitol on January 6 when Congress would certify the results, despite those around him insisting Mr. Biden had won the election.

In a previously unseen video clip, the panel played a quip from a former attorney general, William Barr, who testified that he told Mr. Trump the claims of a rigged election were “bulls—.”

In another, the former president’’ daughter, Ivanka Trump, testified to the committee that she respected Mr. Barr’s view that there was no election fraud. “I accepted what he said.”

Others showed leaders of the extremist Oath Keepers and Proud Boys preparing to storm the Capitol to stand up for Mr. Trump. One rioter after another told the committee they came to the Capitol because Mr. Trump asked them to.

“President Trump summoned a violent mob,” said Mrs. Cheney, who took the lead for much of the hearing. “When a president fails to take the steps necessary to preserve our union — or worse, causes a constitutional crisis — we’re in a moment of maximum danger for our republic.”

There was an audible gasp in the hearing room when Mrs. Cheney read an account that said when Mr. Trump was told the Capitol mob was chanting for Vice President Pence to be hanged for refusing to block the election results, Mr. Trump responded that maybe they were right, that he “deserves it.”

At another point it was disclosed that Representative Scott Perry, a leader of efforts to object to the election results, had sought a pardon from Mr. Trump, which would protect him from prosecution.

When asked about the White House lawyers threatening to resign over what was happening in the administration, Mr. Trump’s son-in-law, Jared Kushner, scoffed that they were “whining.”

Police officers who had fought off the mob consoled one another as they sat in the committee room reliving the violence they faced on January 6. Officer Harry Dunn teared up as bodycam footage showed rioters bludgeoning his colleagues with flagpoles and baseball bats.

The riot left more than 100 police officers injured, many beaten and bloodied, as the crowd of pro-Trump rioters, some armed with pipes, bats, and bear spray, charged into the Capitol. At least nine people who were there died during and after the rioting, including a woman who was shot and killed by police.

President Biden, in Los Angeles for the Summit of the Americas, said many viewers were “going to be seeing for the first time a lot of the detail that occurred.”

Mr. Trump, unapologetic, dismissed the investigation anew — and even declared on social media that January 6 “represented the greatest movement in the history of our country.”

Republicans on the House Judiciary Committee tweeted: “All. Old. News.”