More than a dozen current and former US officials testified behind closed doors in the Trump impeachment probe.

The Trump impeachment inquiry moves into uncharted territory this week as the House Intelligence Committee begins holding public, televised hearings with witnesses.

The first public hearing, with William Taylor, the top US diplomat in Ukraine and George Kent, the deputy US assistant secretary of state for Eastern Europe, will take place on Wednesday. Two days later, the House Intelligence Committee will hold a public hearing with Marie Yovanovitch, the former US ambassador to Ukraine. Several more public hearings have been scheduled for next week.

The witnesses called so far have already testified before House investigators in closed-door sessions as part of the Democratic-led probe.

The inquiry is centred on a July 25 phone call between President Donald Trump and his Ukrainian counterpart, Volodymyr Zelenskyy. During that call, Trump asked the new Ukraine president to launch an investigation into the US president’s leading Democratic rival, Joe Biden, and his son, Hunter, who had served on the board of a Ukrainian gas company.

Just weeks before the call, Trump froze nearly $400m in US military aid to Ukraine. The timing of Trump’s request made during the call prompted speculation that he was using the aid as leverage for personal, political gain.

Following a whistle-blower complaint about the call, Democrats launched an impeachment inquiry of the president. Much of the inquiry so far has taken place behind closed doors, but transcripts of most of the depositions have been released, detailing what appears to be the Trump administration’s more wide-reaching pressure campaign on the Ukrainian government.

Trump maintains he has done nothing wrong, saying there was no “quid pro quo” (Latin for “a favour for a favour”).

As the inquiry moves into the public sphere, here’s a look at who has testified behind closed doors and what they said.

Kurt Volker, former US special envoy for Ukraine

Testified October 3; transcript released November 5; Public testimony scheduled for November 19

A career US diplomat, Kurt Volker resigned from his position as special envoy for Ukraine at the end of September and testified to House investigators on October 3. Volker provided copies of text messages he exchanged with US Ambassador to the European Union Gordon Sondland. He was also instrumental in setting up Trump’s July 25 phone call with Zelenskyy.

Trump’s demands on that call were “quite a surprise”, “extremely unfortunate” and “explosive”, Volker told investigators according to a transcript of his testimony.

Volker, a former special envoy to Ukraine, arrives for a closed-door interview with House investigators as House Democrats proceed with the impeachment inquiry of President Donald Trump [File: Scott Applewhite/AP Photo]

“It creates a problem where all of the things that we’re trying to advance the bilateral relationship, strengthen our support for Ukraine, strengthen the positioning against Russia is now getting sucked into a domestic political debate in the US,” Volker said.

Volker said he warned Trump lawyer Rudy Giuliani in a breakfast meeting on July 19 at the Trump Hotel with Lev Parnas, a Ukrainian American working with Giuliani, that the allegations involving former Vice President Joe Biden and his son Hunter were “simply not credible”.

Read more about Volker’s testimony here.

Marie Yovanovitch, former US ambassador to Ukraine

Testified October 11; transcript released on November 4; Public testimony scheduled for November 15

Marie Yovanovitch, a widely respected career diplomat and former US ambassador to Ukraine, had spoken out in Kyiv against the oligarchy still controlling Ukraine’s economy.

Yovanovitch was recalled in May after being informed by Deputy Secretary of State John Sullivan that she had “done nothing wrong”, but that Trump had “lost confidence” in her, according to a transcript of her testimony.

Former U.S. ambassador to Ukraine Marie Yovanovitch, arrives on Capitol Hill [File: J Scott Applewhite/AP Photo]

Trump spoke negatively of Yovanovitch in his phone call with Zelenskyy.

“The former ambassador for the United States, the woman, was bad news and the people she was dealing with in the Ukraine were bad news, so I just want to let you know that,” Trump told Zelesnkyy, according to White House notes of the call.

Yovanovitch told House investigators on October 11 that she felt threatened by Trump describing her on the call to Zelenskyy as “bad news” a transcript showed.

“I was very concerned,” she said. “I still am.”

Read more about Yovanovitch’s testimony here.

George Kent, deputy assistant secretary of state

Testified on October 15; transcript released November 7; Public testimony scheduled for November 13

An expert on Ukraine and Russia, Deputy Assistant Secretary of State George Kent told investigators he raised red flags about Giuliani’s campaign to pressure Ukraine as early as April, according to a transcript of his testimony.

Kent said that Trump “wanted nothing less than President Zelenskyy to go to the microphone and say investigations, Biden and Clinton,” the transcripts showed.

“Basically, there needed to be three words in the message, and that was the shorthand,” Kent said.

Kent told investigators that that was his understanding of what Trump wanted Zelenskyy to say in order to unlock US military aid.

Kent arrives to testify at a closed-door deposition as part of the impeachment inquiry into US President Donald Trump [File: Carlos Jasso/Reuters]

Clinton, he explained, was “shorthand” for the 2016 presidential campaign. Hillary Clinton was Trump’s Democratic rival. It was a reference to a now-debunked conspiracy theory that Ukraine played a role interfering in the election.

Kent said he memorialised in writing the conversations he was having with other diplomats amid his concerns of “an effort to initiate politically motivated prosecutions that were injurious to the rule of law, both in Ukraine and US”. The memorandum was submitted to the State Department.

191107215202582

He told investigators he was uncomfortable with what he was hearing about Giuliani pushing the investigations and Trump’s special envoy to Ukraine, Kurt Volker, engaging Ukrainian officials on the subject.

“And I told Bill Taylor, ‘that’s wrong, and we shouldn’t be doing that as a matter of US policy,'” Kent said, referring to William Taylor, the top diplomat in Ukraine who has also testified in the inquiry.

Trump’s ambassador to the European Union, Gordon Sondland, had dubbed himself, Volker and Energy Secretary Rick Perry the “three amigos” with a mandate to take the lead on Ukraine policy over the career diplomats, Kent testified.

At one point, Kent said Volker’s assistant, Catherine Croft, asked if anyone had sought investigations from Ukraine. Kent said he hoped the US had not, because “that goes against everything that we are trying to promote in post-Soviet states for the last 28 years, which is the promotion of the rule of law”.

Read more about Kent’s closed-door testimony here.

Fiona Hill, former Russia adviser on the NSC

Testified on October 15; transcript released November 8; Public testimony scheduled for November 21

Fiona Hill, a former White House Russia adviser, testified about an incident in which Trump’s former national security adviser, John Bolton, “immediately stiffened” during a meeting when Sondland “blurted out: Well, we have an agreement” with Mick Mulvaney, the acting White House chief of staff, “for a meeting if these investigations in the energy sector start” – an apparent reference to Burisma, the Ukrainian gas company where Hunter Biden served on the board.

Bolton, who has declined a request by the House to testify, abruptly ended the meeting after the comment, Hill said.

Hill arrives to review her previous testimony in the US House of Representatives impeachment inquiry [File: Leah Millis/Reuters]

Hill also described Bolton’s dismay over the unofficial statecraft of Trump’s personal lawyer, Giuliani.

“He basically said, in fact, he directly said: ‘Rudy Giuliani is a hand grenade that is going to blow everybody up.’ He made it clear that he didn’t feel that there was anything that he could personally do about this,” Hill said, according to the testimony.

Read more about Hill’s testimony here.

P Michael McKinley, former senior adviser to the secretary of state

Testified on October 16; transcript released on November 4

A 37-year career diplomat, Michael McKinley said he quit the State Department out of frustration over Secretary of State Mike Pompeo’s refusal to issue a statement in support of Ambassador Yovanovitch.

“It shouldn’t be difficult to put out a short statement that’s not political, stating clearly that we respect the professionalism, the tenure of Ambassador Yovanovitch in the Ukraine,” McKinley said, according to the transcript of his testimony.

McKinley walks away from a closed-door hearing at the US Capitol [File: Mark Wilson/Getty Images]

After three attempts to get Pompeo to support Yovanovitch in light of Trump’s disparaging remarks in the Zelenskyy phone call, McKinley resigned.

“This situation isn’t acceptable. I am resigning,” McKinley said he told Pompeo.

McKinely told House investigators that “to see the emerging information on [Trump’s] engagement of our missions to procure negative political information for domestic purposes, combined with a failure I saw in the [State Department] building to provide support for our professional cadre in a particularly trying time, I think the combination was a pretty good reason to decide enough, that I had – I had no longer a useful role to play.”

Gordon Sondland, US ambassador to the European Union

Testified on October 17; transcript released on November 5; Public testimony scheduled for November 20

Sondland, a political appointee in his role as US ambassador to the EU, served as a direct go-between for Trump with Zelenskyy. He testified on October 17 that he did not recall much about the effort to pressure Ukraine, but later amended his testimony to say he understood that Trump had conditioned the delivery of US military aid to Ukraine on Zelenskyy opening investigations.

Sondland attended a meeting in Warsaw, Poland, between Zelenskyy and Vice President Mike Pence on September 1, more than a month after Zelenskyy’s phone call with Trump. After the formal meeting, Sondland had a “brief pull-aside conversation” with Andrei Yermak one of Zelenskyy’s senior advisers.

“I said that resumption of US aid would likely not occur until Ukraine provided the public anti-corruption statement that we had been discussing for many weeks,” Sondland said, according to a transcript of his testimony.

US Ambassador to the EU Gordon Sondland arrives for a closed-door hearing of the impeachment inquiry [Pablo Martinez Monsivais/AP Photo]

Sondland described an White House meeting on May 23 with Trump and Energy Secretary Rick Perry and Ambassador Kurt Volker in which the president directed the three of them to work with Giuliani on Ukraine policy.

“He wasn’t even specific about what he wanted us to talk to Giuliani about. He just kept saying, ‘Talk to Rudy, talk to Rudy’,” Sondland told House investigators, according to a transcript released on November 5.

Sondland discussed Giuliani’s demands which “kept getting more insidious” with Secretary of State Pompeo who “rolled his eyes and said, ‘Yes, it’s something we have to deal with.'” Giuliani, Sondland said, “was always swirling around somewhere.”

Read more about Sondland’s testimony here.

William Taylor, top US envoy in Ukraine

Testified October 22; transcript released on November 6; Public testimony scheduled for November 13

William Taylor, the top US diplomat in Ukraine, told the investigators he understood that the security assistance, and not just a White House meeting for Ukraine’s new president, was conditioned on the country committing to investigations of Joe Biden and the 2016 election.

“That was my clear understanding, security assistance money would not come until the president committed to pursue the investigation,” Taylor said.

Politicians asked if he was aware that “quid pro quo” meant “this for that.”

“I am,” Taylor replied.

Taylor is escorted by US Capitol Police as he arrives to testify before House committees as part of the Democrats’ impeachment investigation of President Donald Trump [J Scott Applewhite/AP Photo]

In a telephone call on September 1, “Ambassador Sondland told me that President Trump told him that he wants President Zelenskyy to state publicly that Ukraine will investigate Burisma and alleged Ukrainian interference in the 2016 US election,” Taylor said.

Taylor also testified about his concerns about the dismissal of Yovanovitch as Giuliani took a leading role on Ukraine policy.

Read more about Taylor’s closed-door testimony here.

Laura Cooper, deputy assistant secretary of defence

Testified on October 23; transcript release November 11; Public testimony scheduled for November 20

Laura Cooper, a Defense Department official, testified that the view among US national security was that military aid to Ukraine should not be stopped, but the White House’s chief of staff thought otherwise.

“My sense is that all of the senior leaders of the US national security departments and agencies were all unified in their – in their view that this assistance was essential,” she said. “And they were trying to find ways to engage the president on this.”

Cooper told investigators that, in a series of July meetings at the White House, she came to understand that Trump’s acting chief of staff, Mick Mulvaney, was holding up the military aid for the US ally.

“There was just this issue of the White House chief of staff has conveyed that the president has concerns about Ukraine,” she testified.

When she and others tried to get an explanation, they found none.

“We did not get clarification,” she said.

Cooper arrives for her deposition amid the House impeachment inquiry [Jim Lo Scalzo/EPA-EFE]

She said it was “unusual” to have congressional funds suddenly halted that way, and aides raised concerns about the legality of it. The Pentagon was “concerned” about the hold-up of funds and “any signal that we would send to Ukraine about a wavering in our commitment”, she said.

Cooper told investigators that she was visited in August by Volker, the US special envoy to Ukraine, who explained there was a “statement” that the Ukraine government could make to get the security money flowing.

It was the first she had heard of the quid pro quo that is now the central question of the impeachment inquiry – the administration’s push for the Ukraine government to investigate Trump’s political rivals.

“Somehow, an effort that he was engaged in to see if there was a statement that the government of Ukraine would make,” said Cooper, an assistant defence secretary, “that would somehow disavow any interference in US elections and would commit to the prosecution of any individuals involved in election interference.”

Philip Reeker, acting assistant secretary of state

Testified on October 26; transcript not released

Acting Assistant Secretary of State Philip Reeker testified in a rare Saturday session and told investigators he was disturbed by Trump’s campaign to remove Ambassador Yovanovitch, The Associated Press reported.

Reeker arrives a the Capitol for closed-door interview [Jose Luis Magana/AP Photo]

Reeker said he sought a “proactive statement” from the State Department leaders in support of Yovanovitch. He was told by Undersecretary of State Hale that no such statement would be issued, the AP reported.

Alexander Vindman, US Army Lt Colonel assigned to NSC

Testified on October 29; transcript released November 8; Public testimony scheduled for November 19

US Army Lieutenant-Colonel Alexander Vindman, who has been assigned to the National Security Council (NSC), listened to Trump’s call with Zelenskyy and told House investigators he raised concerns about it with White House lawyers.

“I was concerned by the call,” Vindman said, according to the testimony. “I did not think it was proper to demand that a foreign government investigate a US citizen, and I was worried about the implications for the US government’s support of Ukraine.”

“I realised that if Ukraine pursued an investigation into the Bidens and Burisma, it would likely be interpreted as a partisan play which would undoubtedly result in Ukraine losing the bipartisan support it has thus far maintained. This would all undermine US national security,” he said.

Vindman, a military officer at the National Security Council, departs a closed-door meeting after testifying as part of the House impeachment inquiry into President Donald Trump [File: Patrick Semansky/AP Photo]

Vindman also said that Sondland, the ambassador to the European Union, told Ukrainian officials they would need to investigate the Bidens if they hoped to have a coveted meeting with Trump, according to the transcript.

“He was calling for something, calling for an investigation that didn’t exist into the Bidens and Burisma,” Vindman said. “The Ukrainians would have to deliver an investigation into the Bidens.

191108182018428

“When investigators pushed if the requested investigation was specifically into the Bidens, Vindman responded: “My visceral reaction to what was being called for suggested that it was explicit.”

“There was no ambiguity,” he added.

Vindman also told the House panel that a memo of the July 25 call between Trump and Ukraine’s leader at the centre of the probe was edited to remove a specific reference to Burisma.

Vindman said the rough transcript was edited to replace Burisma with “the company”.

Read more about Vindman’s testimony here.

Catherine Croft, State Department foreign service officer

Testified on October 30; transcript released on November 11

Catherine Croft has worked on Ukraine since 2013 when she was posted to NATO mission in Brussels. From 2015 to 2017, she served on the Ukraine desk at State Department headquarters before joining the National Security Council at the White House.

On July 25, when Trump had his phone call with Zelenskyy, Croft was accompanying Volker to meetings with Ukrainian officials and touring the line of contact between Ukrainian armed forces and Russian-led forces in eastern Ukraine.

According to her opening statement, Croft told investigators she had participated in a conference call on July 18 in which a representative of the Office of Management and Budget (OMB) said acting White House Chief of Staff and OMB Director Mick Mulvaney had placed a hold on Ukraine’s security assistance “at the direction of the president”.

Croft arrives for a closed-door meeting to testify as part of the House impeachment inquiry into Trump on Capitol Hill [File: Andrew Harnik/AP Photo]

Croft said she heard “directly and indirectly – President Trump describe Ukraine as a corrupt country”. During her time at the NSC, Croft said she received several phone calls from former Republican congressman now a lobbyist Bob Livingston “who told me that ambassador Yovanovitch should be fired”.

She also testified about the oversized reach of Giuliani into foreign policy on Ukraine.

Croft told investigators of her “trepidation” of taking on the role in spring of adviser to the special envoy to Ukraine, Kurt Volker, because she worried that Giuliani was influencing Trump to change US policy toward the ally.

She said she theorised that by “painting sort of Ukraine as being against Trump” it could help the president “distract from a narrative” that Russia had interfered in the 2016 US election to help him.

Christopher Anderson, State Department foreign service officer

Testified on October 30; transcript released on November 11

A career Foreign Service Officer since 2005, Christopher Anderson served as a special adviser to Volker for Ukraine from August 2017 to July 12 when he was replaced by Croft.

When Zelenskyy was elected in April, Anderson and his colleagues were optimistic the new president “could re-initiate high-level US engagement”.

But they were concerned by “the negative narrative sparked by Ambassador Yovanovitch’s withdrawal and Giuliani’s statements”, he said in his opening statement.

Anderson returns to the Capitol to review transcripts of his previous interview [File: J Scott Applewhite/AP Photo]

Anderson told investigators that Bolton had warned diplomats in June that Giuliani “was a key voice with the President on Ukraine which could be an obstacle to increased Whtie House engagement”.

“I had the fear that if Giuliani’s narrative took hold, that the Ukrainian Government was an enemy of the President, then it would be very hard to have high-level engagement,” Anderson said, according to a transcript of his testimony.

He said Volker had warned him, “Giuliani is not moving on to other issues, and so this might still be a problem for us moving forward.”

Timothy Morrison, senior director on the NSC

Testified October 31; transcript not released; Public testimony scheduled for November 19

Timothy Morrison, a former 17-year Republican congressional aide who joined Trump’s White House team in 2018, reported directly to former National Security John Bolton and listened to Trump’s phone call with Zelenskyy from the White House situation room.

Morrison told investigators he was concerned that “a potential leak” of the White House’s memorandum of the conversation “would play out in Washington’s polarised environment”, according to his prepared remarks.

Morrison, special assistant to the president and senior director for Europe and Russia at the National Security Council, returns to testify at a closed-door deposition as part of the impeachment inquiry [File: Siphiwe Sibeko/Reuters]

Morrison said he feared Trump’s call with Zelenskyy “would affect the bipartisan support our Ukrainian partners currently experience in Congress” and “would affect the Ukrainian perceptions of the US-Ukraine relationship”.

Morrison backed up Taylor’s testimony and said he and Taylor were both “concerned that the longer the money was withheld, the more questions the Zelenskyy administration would ask about the US commitment to Ukraine.”

David Hale, undersecretary of state for political affairs

Testified on November 6; transcript not released

David Hale, an undersecretary of state for political affairs, intended to tell House investigators that Pompeo was reluctant to defend Yovanovitch because it would hurt efforts to get Ukraine military aid, the Associated Press reported in advance of his testimony on November 6.

Hale arrives for a closed-door deposition as part of the impeachment inquiry into Trump [File: Joshua Roberts/Reuters]

Hale was prepared to say that there was worry about the reaction of Giuliani, who wanted Yovanovitch out, the news agency reported.

Jennifer Williams, special adviser to Vice President Mike Pence

Testified on November 7; transcript not released; Public testimony scheduled for November 19

Jennifer Williams, a career foreign service officer and special adviser to Pence for Europe and Russia, was one of a handful of US officials who listened to the July 25 phone call between the US and Ukrainian leaders.

Williams, special adviser for Europe and Russia in the Office of US Vice President Mike Pence, arrives on Capitol Hill [File: Tom Brenner/Reuters]

Williams told investigators she found Trump’s July call with Zelenskyy unusual because it was political, not diplomatic in nature, CNN reported, citing an unnamed source.

But she did not raise concerns about the call with her superiors and, when asked what Pence knew, said she never heard him mention anything about investigation of the 2016 elections, Burisma or the Bidens.

Editor’s note: Acting Director of National Intelligence Joseph Maguire has also testified as part of the probe, but his testimony – in a public hearing – focused on the handling of the whistle-blower complaint, not specifically on Trump’s dealings with Ukraine. Read about his testimony here.