In a series of tweets in late July, Donald Trump called Elijah Cummings, a Democratic representative from Baltimore and one of his chief congressional critics, a “brutal bully” whose inner-city district was “a disgusting, rat and rodent infected mess.” In September, as facts began spilling out about the President’s pressure campaign on Ukraine to investigate his possible 2020-election rival, the former Vice-President Joe Biden, Cummings endorsed impeachment proceedings against Trump. As chairman of the House Oversight Committee, he then became one of three committee heads running the investigation. “When the history books are written about this tumultuous era,” Cummings said, “I want them to show that I was among those in the House of Representatives who stood up to lawlessness and tyranny.”

Early Thursday morning, Cummings died, in a Baltimore hospital, at the age of sixty-eight. On Capitol Hill, flags were immediately taken down to half-staff to mark his passing, and fulsome statements of praise were issued, including one from Trump, who never apologized for his rant about one of the country’s most prominent African-American leaders. A more substantive tribute to Cummings and the work he cared so much about, however, was taking place behind the “RESTRICTED AREA” signs at the House Intelligence Committee’s offices, where Cummings’s committee was meeting to hear remarkable testimony against Trump, and from one of the President’s own appointees.

When the impeachment inquiry started, a little more than three weeks ago, there were only an anonymous whistle-blower’s complaint and the summary that Trump released of his July 25th phone call with the Ukrainian President. Because the investigation has moved so quickly, it is easy to lose sight of how much has been learned since then. Day after day, in fact, the House’s impeachment inquiry has produced significant revelations that point directly to Presidential culpability. The revelations come from inside the Trump Administration, from professional diplomats and experts who were dismayed that the President and his private attorney, Rudy Giuliani, would conduct a shadow foreign policy toward Ukraine that seemed to have, as its sole motive, personal political benefit. Even those who participated in the scheme, such as the U.S. Ambassador to the European Union, Gordon Sondland, who testified on Thursday, placed the blame squarely with Trump and Giuliani in his written testimony.

Ever since Democrats took control of the House in January, Trump has sought to block them from conducting investigations and oversight of his Administration, defying subpoenas, refusing to send officials to Capitol Hill, and fighting Congress in court. The impeachment inquiry, however, has finally breached the Administration’s blockade. Just this past week, the fired U.S. Ambassador to Ukraine, Marie Yovanovitch; the former National Security Council senior director in charge of Ukraine policy, Fiona Hill; the current State Department deputy assistant secretary in charge of Ukraine policy, George Kent; the Secretary of State’s senior adviser, who quit in protest over the Ukraine affair, last week, Michael McKinley; and Sondland, a wealthy Trump donor turned Ambassador to the E.U., all testified, defying Trump in order to do so, and at considerable risk to their careers. McKinley ended nearly forty years at the State Department to have his say. Kent, Sondland, and Yovanovitch remain U.S. government officials, and could be fired. Both Kent and Yovanovitch are professional diplomats who have given decades of service to their country at the State Department. This is bravery of a sort that has become so rare in our public life as to be almost unimaginable. Denny Heck, another Democrat who sits on the impeachment panel, called Kent and Hill “true American heroes” after listening to their closed-door testimony. According to the House Intelligence Committee chairman, Adam Schiff, those depositions will eventually be made public. The history books that Cummings invoked at the start of the investigation will very likely take note of his final week on this earth.

Partway through her gruelling ten-and-a-half hours of testimony on Monday, Fiona Hill was asked how she came to understand that, despite her formal duties as the top National Security Council adviser on Russia and Ukraine, she was not only not in charge of the policy but no longer being kept in the loop about it. Neither, she would learn, was her boss, John Bolton, who was then the national-security adviser. According to a source present for her deposition, Hill described a meeting in her White House office with Gordon Sondland, whose murky role in Ukraine had alarmed her since an earlier meeting they’d attended in May. Now she asked Sondlond directly: Why was the American Ambassador to Brussels inserting himself in the affairs of a country that fell outside of his diplomatic portfolio and wasn’t even a member of the E.U.? “She challenged him on who gave him her portfolio, and he said the President,” the source told me. “It was news to her, and it was news to Bolton.”

Trump himself, in other words, was putting together a rogue foreign-policy team, run by Giuliani, the President’s private attorney, that would go outside normal N.S.C. and State Department channels to pressure Ukraine. The effort would eventually result in Trump abruptly firing Yovanovitch, the U.S. Ambassador to Ukraine, at Giuliani’s behest, and withholding a White House meeting from Volodymyr Zelensky, the new Ukrainian President, until he agreed to investigate unsubstantiated allegations involving Biden’s son, and also discredited conspiracy theories involving Ukraine working against Trump in the 2016 U.S. Presidential election. At the same time, Trump was refusing to release hundreds of millions of dollars in military aid to Ukraine, although it had been legally authorized by Congress.

The basic outlines of the plot have been known since the start of the impeachment inquiry, but the testimony by Hill and others this week both confirms key details and adds important information that shows how much the President was directly implicated. Trump ordered Sondland, a million-dollar contributor to his Inauguration; Kurt Volker, his Ukraine special envoy; and Energy Secretary Rick Perry to take control of Ukraine policy. (Kent, the State diplomat who was, like Hill, cut out of the loop, said that they called themselves “the three amigos.”) Trump personally ordered Yovanovitch’s firing. Trump personally ordered the withholding of military aid. The scandal, as this week showed, is about a lot more than saying “do us a favor though” in a phone call.

“The problem here is the President—all this begins and ends with him,” Tom Malinowski, a former senior State Department official under President Obama who is now a Democratic representative from New Jersey and a participant in the impeachment inquiry, told me. Malinowski has sat through dozens of hours of testimony in the past week, much of which, he said, was strikingly consistent in pointing toward Trump. “There was a good official Ukraine policy, arguably even stronger in this Administration than in the previous because they were willing to send the [anti-tank missiles] Javelins. But then, at first gradually and then completely, this policy was superseded by a shadow policy directed by the President through Giuliani and his cronies to advance his partisan interest over the national interest.”

In terms of piercing the Trump Administration’s stonewalling of Congress, Hill’s decision to appear on Monday, in defiance of White House demands, was crucial. Hill is the first former White House official to testify in the investigation—that she has done so without the White House going to court to stop her, her lawyer, Lee Wolosky, told me, means “the floodgates may have opened.” Wolosky and the White House counsel’s office exchanged a series of letters into the early-morning hours before Hill’s testimony, sparring over Trump’s assertion of executive privilege and refusal to participate in the impeachment inquiry. Wolosky wrote that Hill would testify anyway, and, essentially, called the White House’s bluff. The fact that Hill’s testimony went forward unchallenged “makes it much more difficult for them to hold back testimony of other White House officials, and certainly of former White House officials,” Wolosky said. “They can’t come back and say, ‘We want to go to court and try to litigate it.’ Any judge will say, ‘You waived your rights. You sat on your hands.’ ”