The fault lines are most easily seen in the witnesses summoned to testify in open hearings this far: Democrats’ first public hearings last week featured Taylor, Kent and Yovanovitch and will continue this week with Sondland, Williams and Pentagon official Laura Cooper, among others. Republicans, meanwhile, have asked for an additional nine witnesses, only some of whom were greenlit by the majority, including Volker, National Security Council official Tim Morrison and Trump appointee David Hale.

Several of the witnesses have offered conflicting accounts or interpretations of certain events, making it difficult at times to render a conclusive judgment on who is right. Below are a few of the most prominent examples where key witnesses have differed:

A July 10 meeting at the White House

A meeting in John Bolton’s office with two Ukrainian officials—top Zelensky adviser Andriy Yermak and national security adviser Oleksandr Danyliuk—that was attended by former NSC official Fiona Hill, Vindman, Sondland and Volker has become a focal point of the impeachment inquiry because it solidified the White House officials’ suspicions that a shadow Ukraine policy was being pursued to push Trump’s political objectives, according to Hill and Vindman’s testimonies.

Bolton and his deputy Charles Kupperman, have so far declined to testify.

Kupperman had asked a federal judge to clarify the legal dispute between the legislative and executive branches, but his lawsuit was made moot when Congress withdrew its subpoena for him, citing time constraints.

Meanwhile, their shared lawyer, Chuck Cooper, told lawmakers that Bolton has knowledge of “many relevant meetings and conversations that have not yet been discussed in the testimonies thus far” but won’t testify until a federal judge resolves the dispute between Congress and the White House.

Both Hill and Vindman told lawmakers that Bolton cut the meeting short when Sondland started discussing specific investigations Ukraine would need to launch in order to meet with Trump, but that Sondland continued the discussion in a later debriefing in the White House’s Ward Room that Bolton didn’t attend. Taylor also testified that Hill and Vindman briefed him on the meeting in Bolton’s office, and Sondland’s mention of investigations, in a call on July 19.

Former NSC official Fiona Hill. | Andrew Harnik/AP Photo

“Ambassador Sondland started to speak about Ukraine delivering specific investigations in order to secure the meeting with the president,” Vindman testified, “at which time Ambassador Bolton cut the meeting short ... following this meeting, there was a scheduled debriefing during which Ambassador Sondland emphasized the importance that Ukraine deliver the investigations into the 2016 election, the Bidens and Burisma.”

Hill testified that Sondland “started to basically talk about discussions that he had had with the chief of staff,” Mick Mulvaney. “He mentioned Mr. Giuliani, but then I cut him off because I didn't want to get further into this discussion at all.”

She also brought up Volker directly when asked whether she personally heard Sondland mention Burisma, the Ukrainian energy company on whose board Hunter Biden sat. “Mr. Vindman was also there?” Hill was asked. “Correct,” she replied. “And Kurt Volker.”

Volker, though, testified that neither Giuliani nor investigations were mentioned during the meetings. “No,” he replied, when asked whether Giuliani’s activities in Ukraine or “anything about the investigations” was brought up.

Sondland testified that he doesn’t “remember” raising the issue of Burisma or mentioning investigations in either meeting. “I can’t say that the word ‘Burisma’ wasn't mentioned,” he testified. “I don't know if I mentioned it or if Ambassador Volker did or if Mr. Vindman — I have no idea.”

The July 25 call

The witnesses’ interpretations of the propriety of the July 25 call between Trump and Zelensky, in which Trump specifically asked Zelensky to look into the Bidens and investigate potential Ukrainian interference in 2016, has varied as well, including within certain officials’ own depositions.

Morrison, a former Republican Senate staffer and arms-control specialist who was selected by Bolton to replace Hill as a top Europe and Russia adviser on the NSC, testified that he “was not concerned that anything illegal was discussed” on the call.

But he briefed White House lawyer John Eisenberg on the conversation right after it ended, he said, because he was concerned it would leak, and recommended that access to records of the call be restricted.

Morrison also said, however, that Giuliani, Burisma and 2016 election interference “were all issues I tried to stay away from ... because it had nothing to do with our policy process,” and noted that he became “concerned” about how “obsequious” Zelensky was being to Trump and about the “parallel process” occurring on Ukraine that Hill had warned him about before he replaced her.

According to texts exchanged between Volker and Sondland on Aug. 9, Morrison reluctantly agreed to set up a Trump-Zelensky meeting because Trump wanted “the deliverable,” according to Sondland, presumably of Ukraine’s promise to launch the requested investigations.

Morrison also told lawmakers he kept Taylor apprised of the back-channel’s efforts, briefing him on the July 25 call, calls between Sondland and Trump, calls between Sondland and Yermak, and Trump’s desire to withhold all security aid from Ukraine—which Taylor said he was prepared to resign over.

Morrison testified that his conversations with Taylor were “a normal part of the coordination process” since he was Taylor’s “chief conduit for information related to White House deliberations” about Ukraine. According to Taylor’s testimony, Morrison told him the July 25 call “could have been better,” a comment the NSC official explained as reflecting his disappointment that the two leaders hadn’t discussed Zelensky’s “reform agenda.”

Vindman, meanwhile, testified that he was deeply concerned about the July 25 call. He said that while he couldn’t determine whether anything illegal had occurred because he is not a lawyer, he also briefed Eisenberg on its contents and considered Trump’s request that Ukraine investigate a U.S. citizen to be improper.

Volker testified that he cautioned the Ukrainians not to get “sucked in” to U.S. domestic politics after being briefed on the phone call. But he sent a text message to Yermak on the morning of July 25 that conditioned a Trump-Zelensky White House meeting on investigations, and was negotiating a public statement by Zelensky that would commit him to opening the probes Trump demanded.

“Assuming President Zelensky convinces Trump he will investigate/get to the bottom of what happened in 2016, we will nail down date for visit to Washington. Good luck,” Volker wrote on July 25.

Handling of the call record

A key disagreement has emerged over why the record of the July 25 call was placed in a top-secret system used by the NSC to store code-word-level information, and whether it was edited to remove the word “Burisma.”

Morrison told lawmakers that when he couldn’t find the record of the call in the normal portal, he learned from the Executive Secretariat staff that they’d put it in the highly classified system on Eisenberg’s orders—but Eisenberg told Morrison that the staff had misunderstood his request to “restrict access” to the call and didn’t intend for it to be placed in the code-word system, known as NICE.

The call was not removed from the system after that conversation, however. As Morrison was preparing for the Trump-Zelensky meeting at the United Nations in September, he tried to get access to the call record again, to no avail. “So I recall talking to John at that time of, John, did we ever figure out how to get this thing moved down?” he testified.

Vindman’s testimony, meanwhile, implied that the record was deliberately placed into the system. He told lawmakers that Michael Ellis, a White House lawyer and Eisenberg’s deputy, was the first to suggest placing the record of Trump’s July 25 call with Zelensky into the system. Eisenberg, as the NSC’s top legal adviser, made the final call to place the call record there after Ellis proposed the idea, he said.

Vindman said he didn’t believe Ellis had “malicious intent” in suggesting the call record be placed on the top-secret server, and that Eisenberg ultimately “gave the go-ahead” to do so.

Impeachment investigators have sought testimony from Eisenberg and Ellis, but the White House has barred them from testifying, citing an aggressive interpretation of past precedent on executive privilege and casting the entire impeachment process as illegitimate and unconstitutional.

Morrison also appeared to disagree with both Vindman and Williams—Pence’s aide on loan from the State Department—on whether the word “Burisma” was brought up during the July 25 Trump-Zelensky call.

Vindman and Williams, both of whom listened to the call, testified that Zelensky mentioned Burisma by name.

Vindman, a fluent Ukrainian speaker, said he ultimately suggested several edits to the memorandum of the call that the White House eventually released to the public in September — some of which he described as “significant.” He said those changes were never included in the final version that was made public.

Lt. Col. Alexander Vindman. | Alex Wong/Getty Images

One of those edits was the addition of a phrase in which Trump referenced “recordings” detailing the unsubstantiated allegations against Biden.

Vindman also told investigators that while the call record says Zelensky only mentioned “the company,” he recalls Zelensky saying instead: “Burisma that you mentioned.”

The fact that Zelensky identified Burisma was important, Vindman said, because it “seemed to suggest to me that he was prepped for this call,” and he knew that Trump’s reference to Biden referred specifically to Burisma.

But a final summary of the call put out by the White House makes no mention of Burisma, and Morrison testified that he didn’t “believe” Burisma was mentioned on the call specifically. He also said he doesn’t recall anyone suggesting edits to the record to reflect Zelensky’s mention of Burisma.

“Had I recalled or had in my notes that was mentioned, yes, I would have agreed to the edit,” Morrison said.