Hill previously told impeachment investigators in her closed-door deposition that she resented the smear campaign run against the former U.S. ambassador to Ukraine Marie Yovanovitch by Trump's personal lawyer Rudy Giuliani.
Hill also is a key witness about the former national security adviser John Bolton, who has been described as an important player in the Ukraine saga but from whom Congress has not heard directly.
Bolton, per Hill, warned about the "drug deal" being cooked up by Trump's deputies with Ukraine and about the role played by Giuliani, whom Hill said Bolton called a "hand grenade that is going to blow everybody up."
In his testimony Wednesday, Sondland didn't dispute much of what Holmes has told investigators about the episode, but there was one key discrepancy — over the specific words he used.
Holmes said that Sondland told him that Trump only cared about "big stuff" that affected him, like what Holmes called the "Biden investigation" Trump wanted from Ukraine.
Sondland says he didn't know in real time that the investigation connected with the word "Burisma" — a Ukrainian company that for a time paid the son of former Vice President Joe Biden — was, in effect, code for the Biden family.
But Hill testified Thursday that it "was very apparent to me that was what Rudy Giuliani intended."
In his closing remarks, House Intelligence Committee Chairman Adam Schiff, D-Calif., drew a parallel between this impeachment probe and Watergate, saying that Trump's alleged transgressions are "beyond anything that Nixon did."
The difference he said is between this Congress and that one, in which Republicans gradually stopped supporting President Nixon. "Where is Howard Baker?" Schiff asked, referring to Republican senator from that time who helped lead the Watergate investigation.
Schiff said that in his view, "there is nothing more dangerous than an unethical president who believes he is above the law. We are better than that," Schiff said, banging the gavel down to close the session.
What comes next?
One question raised by the Thursday session — and not yet answered definitively by Democrats — is whether it will be the last.
Schiff, who has been leading this phase of the impeachment inquiry, hasn't said definitively whether the hearing would end his portion of the process.
That matters because it affects the timing of the balance of Democrats' putative impeachment program: Once Schiff's panel concludes its work, action could then shift to the House Judiciary Committee, which would need to initiate and advance articles of impeachment to the full House.
At her weekly news conference Thursday, Pelosi said there are no decisions yet on the timeline for impeachment.
She deferred to committees of jurisdiction about any additional open hearings or deposition, but said the facts are "uncontested" as to what happened. Pelosi repeatedly said if the president has something to offer that is exculpatory he should submit "under oath."
She pushed back at a question about the impeachment process not being bipartisan, as she initially said it needed to be, saying "if Republicans are denial about the facts, if the Republicans do not want to honor their oath of office then I don't think we should be characterized in any way because we are patriotic."
The speaker said the president has responded to the inquiry in a way that "is beneath the dignity" of the office of the presidency and added he sets "a very bad example for our children in the manner in which he behaves and speaks."
Asked about waiting for the legal battles to play out Pelosi said "we cannot be at the mercy of the courts." She said the "that's a technique on the part of the administration" to delay.
"We are moving at the pace that truth takes us," Pelosi said.