Former U.S. ambassador to Ukraine Marie Yovanovitch’s testimony was the big public spectacle on Friday. The bigger news in the Ukraine scandal appears to have come later in the day in a private deposition.

It came from David Holmes, an aide to top U.S. diplomat in Ukraine William B. Taylor Jr. Taylor said this week that Holmes overheard President Trump speaking with Ambassador to the European Union Gordon Sondland the day after Trump’s call with Ukraine’s president in July.

And it turns out Holmes fills in a number of key details that Taylor didn’t.

Below are some key points from his opening statement, which CNN obtained.

1. Sondland’s testimony continues to crumble

At three distinct points, we have seen Sondland’s testimony called into question. The first time was when other witnesses said he talked about a quid pro quo with Ukrainian officials on July 10, which Sondland soon confirmed via clarified testimony. The second was this week, when Taylor disclosed that Holmes had overheard a Sondland call with Trump on July 26 that Sondland had failed to mention and in which Trump asked about the investigations he was asking for. “Sondland will address any issues that arise from this in his testimony next week,” his lawyer said Wednesday.

And now Holmes undermines a central claim in Sondland’s testimony: That Sondland didn’t know that Trump and his personal lawyer Rudolph W. Giuliani’s interest in investigating a Ukrainian company that employed Joe Biden’s son Hunter Biden had anything to do with the Biden family.

“I noted that there was ‘big stuff’ going on in Ukraine, like a war with Russia,” Holmes says of his conversation with Sondland on July 26, “and Ambassador Sondland replied that he meant ‘big stuff’ that benefits the president, like the ‘Biden investigation’ that Mr. Giuliani was pushing.”

The quote about the “Biden investigation” is key. Sondland said in his deposition that he had pushed for an investigation into Burisma Holdings, which had employed Hunter Biden, but that he didn’t know there was any connection to the Bidens.

“But I did not understand, until much later,” Sondland said as of late May, “that Mr. Giuliani’s agenda might have also included an effort to prompt the Ukrainians to investigate Vice President Biden or his son or to involve Ukrainians, directly or indirectly, in the President’s 2020 reelection campaign.”

That was tough to swallow, though, given that Giuliani’s efforts to target the Bidens were reported by the New York Times in early May — and that Trump himself lodged his Biden conspiracy theory publicly on May 19. Yet even as of August, Sondland claimed in his testimony, “I did not know until more recent press reports that Hunter Biden was on the board of Burisma.” Sondland explained in his testimony that he hadn’t read the news coverage, even though aides compiled it for him and he was focused on Ukraine policy during this time.

Holmes’s testimony quotes Sondland explicitly referring to this as the “Biden investigation” in July, which suggests there was a reason the ambassador’s testimony didn’t make sense. Sondland will testify alongside others on Wednesday, and his hot seat just got significantly hotter.

2. Another quid pro quo confirmation

Holmes says Taylor told him that on a June 28 call he had with Ukraine President Volodymyr Zelensky and the “three amigos” — Sondland, special envoy to Ukraine Kurt Volker and Energy Secretary Rick Perry — “it was made clear that some action on a Burisma/Biden investigation was a precondition for an Oval Office meeting.”

This detail, notably, was not part of Taylor’s own testimony, though Taylor quickly came to believe that such a meeting was indeed conditioned on Ukraine launching such an investigation.

Taylor testified that on the June 28 call, before Zelensky was added to the line, Sondland said he didn’t want interagency officials on the call, because “he wanted to make sure no one was transcribing or monitoring as they added President Zelensky to the call.”

Taylor added: “Also, before President Zelensky joined the call, Ambassador Volker separately told the U.S. participants that he, Ambassador Volker, planned to be explicit with President Zelensky in a one-on-one meeting in Toronto on July 2. In that meeting, Ambassador Volker planned to make clear what President Zelensky should do to get the White House meeting.”

Taylor didn’t indicate in his opening statement what Volker said he planned to tell Zelensky.

3. He was spurred by GOP defenses of Trump

Holmes’s account is something he says he didn’t consider to be relevant — until he saw some of the defenses of Trump.

Holmes mentions that Trump defenders have argued that perhaps Trump himself wasn’t personally involved in the quid pro quos. He also mentions a GOP argument that was prominent during Wednesday’s hearing featuring Taylor and top State Department aide George Kent: that the witnesses didn’t have firsthand knowledge of some of the key events.

“I came to realize I had firsthand knowledge regarding certain events on July 26,” he said, referring to the date of his overhearing the Sondland-Trump call, “that had not otherwise been reported and that those events potentially bore on the question of whether the president did, in fact, have knowledge that those officials were using the levers of our diplomatic power to induct the new Ukrainian president to announce the opening of a particular criminal investigation.”

It’s worth noting that, despite early GOP attempts to portray Holmes as a partisan — on Friday they promoted a photo of him shaking hands with Barack Obama — he won an award in 2014 after raising concerns about Obama’s Afghanistan policy. Holmes, who served in Afghanistan, was awarded for his “constructive dissent.”

Holmes doesn’t directly say that his testimony contradicts the GOP’s arguments, but it’s certainly suggested. And it makes his full deposition, which we have yet to see, worth paying close attention to.