More than perhaps any insider account that has emerged, the recollections of the aide, Cassidy Hutchinson, demolished the fiction of a president who had nothing to do with what happened. Each revelation was stunning on its own: Mr. Trump knew that weapons were in the crowd as he exhorted supporters to “fight like hell,” and even tried to stop anyone from disarming them. He was so determined to join the mob at the Capitol that he lashed out at his Secret Service detail for refusing to take him. And he was so nonchalant about the bedlam he had unleashed that he suggested Vice President Mike Pence might deserve to be executed for refusing to overturn the election.

But when added together, the various disclosures have produced the clearest picture yet of an unprecedented attempt to subvert the traditional American democratic process, with a sitting president who had lost at the ballot box planning to march with an armed crowd to the Capitol to block the transfer of power, brushing aside manifold concerns about the potential for violence along the way.

“The innocent explanations for Trump’s conduct seem virtually impossible to credit following the testimony we have seen,” said Joshua Matz, who served as a lawyer for House Democrats during both of Mr. Trump’s impeachment trials in the Senate. “At the very least, they powerfully shift the burden to Trump and his defenders to offer evidence that he did not act with a corrupt, criminal state of mind.”