D avid Sakvarelidze was five months into a new job as Ukraine’s reformist deputy chief prosecutor when a witness came forward with intelligence that would change the course of everything.

The witness, a sand producer in the Kiev region, complained of men extorting hundreds of thousands of dollars. It took a while to persuade the man to give evidence. But when he did, and the investigation began, the trail led to two of the country’s highest-placed prosecutors.

A search of the men’s apartments revealed a scene that looked like a comic heist: bags full of cash, diamonds and other precious stones. But that was not the only incriminating evidence. Documents seized at the time indicated the men appeared to have a connection to the top prosecutor in the land, Viktor Shokin.

Police found copies of Shokin’s passports, property registration certificates and even his licence to carry firearms. One of the two men, it transpired, was Shokin’s former driver who had subsequently climbed the ranks behind his boss.

For Sakvarelidze, there were clear suspicions the two men may have been carrying out the business of the chief. But his attempts to investigate were frustrated. Soon, he faced a corruption investigation himself. At loggerheads with Shokin, he was pushed out of his job within the year.

The top prosecutor would also depart in March 2016, at the behest of US vice-president Joe Biden. It was an intervention into local politics that would come back to haunt both Biden and Ukraine.

Trump impeachment: Who's who in the Ukraine scandal Show all 26 1 /26 Trump impeachment: Who's who in the Ukraine scandal Trump impeachment: Who's who in the Ukraine scandal Donald Trump Accused of abusing his office by pressing the Ukrainian president in a July phone call to help dig up dirt on Joe Biden, who may be his Democratic rival in the 2020 election. He also believes that Hillary Clinton’s deleted emails - a key factor in the 2016 election - may be in Ukraine, although it is not clear why. EPA Trump impeachment: Who's who in the Ukraine scandal The Whistleblower Believed to be a CIA agent who spent time at the White House, his complaint was largely based on second and third-hand accounts from worried White House staff. Although this is not unusual for such complaints, Trump and his supporters have seized on it to imply that his information is not reliable. Expected to give evidence to Congress voluntarily and in secret. Getty Trump impeachment: Who's who in the Ukraine scandal The Second Whistleblower The lawyer for the first intelligence whistleblower is also representing a second whistleblower regarding the President's actions. Attorney Mark Zaid said that he and other lawyers on his team are now representing the second person, who is said to work in the intelligence community and has first-hand knowledge that supports claims made by the first whistleblower and has spoken to the intelligence community's inspector general. The second whistleblower has not yet filed their own complaint, but does not need to to be considered an official whistleblower. Getty Trump impeachment: Who's who in the Ukraine scandal Rudy Giuliani Former mayor of New York, whose management of the aftermath of the September 11 attacks in 2001 won him worldwide praise. As Trump’s personal attorney he has been trying to find compromising material about the president’s enemies in Ukraine in what some have termed a “shadow” foreign policy. In a series of eccentric TV appearances he has claimed that the US state department asked him to get involved. Giuliani insists that he is fighting corruption on Trump’s behalf and has called himself a “hero”. AP Trump impeachment: Who's who in the Ukraine scandal Volodymyr Zelensky The newly elected Ukrainian president - a former comic actor best known for playing a man who becomes president by accident - is seen frantically agreeing with Trump in the partial transcript of their July phone call released by the White House. With a Russian-backed insurgency in the east of his country, and the Crimea region seized by Vladimir Putin in 2014, Zelensky will have been eager to please his American counterpart, who had suspended vital military aid before their phone conversation. He says there was no pressure on him from Trump to do him the “favour” he was asked for. Zelensky appeared at an awkward press conference with Trump in New York during the United Nations general assembly, looking particularly uncomfortable when the American suggested he take part in talks with Putin. AFP/Getty Trump impeachment: Who's who in the Ukraine scandal Mike Pence The vice-president was not on the controversial July call to the Ukrainian president but did get a read-out later. However, Trump announced that Pence had had “one or two” phone conversations of a similar nature, dragging him into the crisis. Pence himself denies any knowledge of any wrongdoing and has insisted that there is no issue with Trump’s actions. It has been speculated that Trump involved Pence as an insurance policy - if both are removed from power the presidency would go to Democratic House Speaker Nancy Pelosi, something no Republican would allow. AP Trump impeachment: Who's who in the Ukraine scandal Rick Perry Trump reportedly told a meeting of Republicans that he made the controversial call to the Ukrainian president at the urging of his own energy secretary, Rick Perry, and that he didn’t even want to. The president apparently said that Perry wanted him to talk about liquefied natural gas - although there is no mention of it in the partial transcript of the phone call released by the White House. It is thought that Perry will step down from his role at the end of the year. Getty Trump impeachment: Who's who in the Ukraine scandal Joe Biden The former vice-president is one of the frontrunners to win the Democratic nomination, which would make him Trump’s opponent in the 2020 election. Trump says that Biden pressured Ukraine to sack a prosecutor who was investigating an energy company that Biden’s son Hunter was on the board of, refusing to release US aid until this was done. However, pressure to fire the prosecutor came on a wide front from western countries. It is also believed that the investigation into the company, Burisma, had long been dormant. Reuters Trump impeachment: Who's who in the Ukraine scandal Hunter Biden Joe Biden’s son has been accused of corruption by the president because of his business dealings in Ukraine and China. However, Trump has yet to produce any evidence of corruption and Biden’s lawyer insists he has done nothing wrong. AP Trump impeachment: Who's who in the Ukraine scandal William Barr The attorney-general, who proved his loyalty to Trump with his handling of the Mueller report, was mentioned in the Ukraine call as someone president Volodymyr Zelensky should talk to about following up Trump’s preoccupations with the Biden’s and the Clinton emails. Nancy Pelosi has accused Barr of being part of a “cover-up of a cover-up”. AP Trump impeachment: Who's who in the Ukraine scandal Mike Pompeo The secretary of state initially implied he knew little about the Ukraine phone call - but it later emerged that he was listening in at the time. He has since suggested that asking foreign leaders for favours is simply how international politics works. Gordon Sondland testified that Pompeo was "in the loop" and knew what was happening in Ukraine. Pompeo has been criticised for not standing up for diplomats under his command when they were publicly criticised by the president. AFP via Getty Trump impeachment: Who's who in the Ukraine scandal Nancy Pelosi The Democratic Speaker of the House had long resisted calls from within her own party to back a formal impeachment process against the president, apparently fearing a backlash from voters. 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The Washington Post awarded Schiff a “four Pinocchios” rating, its worst rating for a dishonest statement. Reuters Trump impeachment: Who's who in the Ukraine scandal Lev Parnas and Igor Fruman Florida-based businessmen and Republican donors Lev Parnas (pictured with Rudy Giuliani) and Igor Fruman were arrested on suspicion of campaign finance violations at Dulles International Airport near Washington DC on 9 October. Separately the Associated Press has reported that they were both involved in efforts to replace the management of Ukraine's gas company, Naftogaz, with new bosses who would steer lucrative contracts towards companies controlled by Trump allies. There is no suggestion of any criminal activity in these efforts. Reuters Trump impeachment: Who's who in the Ukraine scandal William Taylor The most senior US diplomat in Ukraine and the former ambassador there. As one of the first two witnesses in the public impeachment hearings, Taylor dropped an early bombshell by revealing that one of his staff – later identified as diplomat David Holmes – overheard a phone conversation in which Donald Trump could be heard asking about “investigations” the very day after asking the Ukrainian president to investigate his political enemies. Taylor expressed his concern at reported plans to withhold US aid in return for political smears against Trump’s opponents, saying: “It's one thing to try to leverage a meeting in the White House. It's another thing, I thought, to leverage security assistance -- security assistance to a country at war, dependent on both the security assistance and the demonstration of support." Getty Images Trump impeachment: Who's who in the Ukraine scandal George Kent A state department official who appeared alongside William Taylor wearing a bow tie that was later mocked by the president. He accused Rudy Giuliani, Mr Trump’s personal lawyer, of leading a “campaign of lies” against Marie Yovanovitch, who was forced out of her job as US ambassador to Ukraine for apparently standing in the way of efforts to smear Democrats. Getty Images Trump impeachment: Who's who in the Ukraine scandal Marie Yovanovitch One of the most striking witnesses to give evidence at the public hearings, the former US ambassador to Ukraine received a rare round of applause as she left the committee room after testifying. Canadian-born Yovanovitch was attacked on Twitter by Donald Trump while she was actually testifying, giving Democrats the chance to ask her to respond. She said she found the attack “very intimidating”. Trump had already threatened her in his 25 July phone call to the Ukrainian president saying: “She’s going to go through some things.” Yovanovitch said she was “shocked, appalled and devastated” by the threat and by the way she was forced out of her job without explanation. REUTERS Trump impeachment: Who's who in the Ukraine scandal Alexander Vindman A decorated Iraq War veteran and an immigrant from the former Soviet Union, Lt Col Vindman began his evidence with an eye-catching statement about the freedoms America afforded him and his family to speak truth to power without fear of punishment. One of the few witnesses to have actually listened to Trump’s 25 July call with the Ukrainian president, he said he found the conversation so inappropriate that he was compelled to report it to the White House counsel. Trump later mocked him for wearing his military uniform and insisting on being addressed by his rank. Getty Images Trump impeachment: Who's who in the Ukraine scandal Jennifer Williams A state department official acting as a Russia expert for vice-president Mike Pence, Ms Williams also listened in on the 25 July phone call. She testified that she found it “unusual” because it focused on domestic politics in terms of Trump asking a foreign leader to investigate his political opponents. Getty Images Trump impeachment: Who's who in the Ukraine scandal Kurt Volker The former special envoy to Ukraine was one of the few people giving evidence who was on the Republican witness list although what he had to say may not have been too helpful to their cause. He dismissed the idea that Joe Biden had done anything corrupt, a theory spun without evidence by the president and his allies. He said that he thought the US should be supporting Ukraine’s reforms and that the scheme to find dirt on Democrats did not serve the national interest. Getty Images Trump impeachment: Who's who in the Ukraine scandal Tim Morrison An expert on the National Security Council and another witness on the Republican list. He testified that he did not think the president had done anything illegal but admitted that he feared it would create a political storm if it became public. He said he believed the moving the record of the controversial 25 July phone call to a top security server had been an innocent mistake. Getty Images Trump impeachment: Who's who in the Ukraine scandal Gordon Sondland In explosive testimony, one of the men at the centre of the scandal got right to the point in his opening testimony: “Was there a quid pro quo? Yes,” said the US ambassador to the EU who was a prime mover in efforts in Ukraine to link the release of military aid with investigations into the president’s political opponents. He said that everyone knew what was going on, implicating vice-president Mike Pence and secretary of state Mike Pompeo. The effect of his evidence is perhaps best illustrated by the reaction of Mr Trump who went from calling Sondland a “great American” a few weeks earlier to claiming that he barely knew him. AP Trump impeachment: Who's who in the Ukraine scandal Laura Cooper A Pentagon official, Cooper said Ukrainian officials knew that US aid was being withheld before it became public knowledge in August – undermining a Republican argument that there can’t have been a quid pro quo between aid and investigations if the Ukrainians didn’t know that aid was being withheld. Getty Images Trump impeachment: Who's who in the Ukraine scandal David Hale The third most senior official at the state department. Hale testified about the treatment of Marie Yovanovitch and the smear campaign that culminated in her being recalled from her posting as US ambassador to Ukraine. He said: “I believe that she should have been able to stay at post and continue to do the outstanding work.” EPA Trump impeachment: Who's who in the Ukraine scandal Fiona Hill Arguably the most confident and self-possessed of the witnesses in the public hearings phase, the Durham-born former NSC Russia expert began by warning Republicans not to keep repeating Kremlin-backed conspiracy theories. In a distinctive northeastern English accent, Dr Hill went on to describe how she had argued with Gordon Sondland about his interference in Ukraine matters until she realised that while she and her colleagues were focused on national security, Sondland was “being involved in a domestic political errand”. She said: “I did say to him, ‘Ambassador Sondland, Gordon, this is going to blow up’. And here we are.” AP Trump impeachment: Who's who in the Ukraine scandal David Holmes The Ukraine-based diplomat described being in a restaurant in Kiev with Gordon Sondland while the latter phoned Donald Trump. Holmes said he could hear the president on the other end of the line – because his voice was so “loud and distinctive” and because Sondland had to hold the phone away from his ear – asking about the “investigations” and whether the Ukrainian president would cooperate. REUTERS

Shokin’s year atop the prosecutor’s office was for a long time remembered simply as the time of the “diamond prosecutors”.

All that changed with the intervention of Donald Trump. The American president's description of Shokin as “that very good” prosecutor, quoted during his now-infamous 25 July call with President Volodymyr Zelensky, certainly surprised most Ukrainians. For the former prosecutor, it was a chance to rehabilitate himself.

The wild conspiracy theory on which Trump based his assertion – that Joe Biden had Shokin removed to stop him investigating wrongdoing in his son’s gas company – has already been widely debunked.

Put simply, the chronology doesn’t work – the investigation into Burisma, where Hunter worked, was dormant by the time Shokin was pushed out. It would also represent a major historical anomaly. During Shokin’s 13 months in office, not one major figure was convicted. No oligarch. No politician. No ranking bureaucrat. It would appear unlikely he was in the middle of breaking the habit with the Bidens.

But Shokin himself has put his weight behind the complimentary Trumpian narrative.

In an affidavit, submitted in September in an unconnected extradition case involving oligarch Dmytro Firtash, the former prosecutor said he had been dismissed because he refused to heed the advice of then-President Petro Poroshenko to drop an investigation.

Joe Biden speaks in Ukraine’s parliament in December 2015. It was on this trip that he pressed Petro Poroshenko to fire his much-criticised general prosecutor (Reuters)

“I was forced out because … I was leading a wide-ranging corruption probe into Burisma Holdings, where Hunter Biden was a member of the board,” the statement reads.

Yet the image of Shokin as a crusading, independent prosecutor is inconsistent with the picture given by half a dozen former colleagues interviewed for this piece.

Unanimously, they described Shokin as a “dependent” creature; a man made in the image of whoever was his patron at the time.

In three terms in office, Shokin served three presidents as either deputy prosecutor or chief prosecutor. He made himself useful to all three, the sources say. He made himself especially indispensable to Poroshenko, with whom he has been linked since at least 2001.

“Shokin was quiet, unassuming, and he always fulfilled his orders,” says Oleksandr Martynenko, a prominent Ukrainian journalist who worked as press secretary to Leonid Kuchma, the first president under whom Shokin served.

“Shokin understood the hints, didn’t make scandals, and that’s how he survived and climbed the ladder in the first place.”

Born in Kiev in 1952, Viktor Shokin studied at the Ukrainian Academy of Agriculture, later graduating from the prestigious Kharkiv legal institute. After that followed three decades in the prosecutors’ office.

The first chunk of that career was spent as a lowly investigator. Shokin’s break came in the late 1990s, when he was chosen to head Unit 30, a new division in the Kiev prosecutors’ office devoted to organised crime.

And then, in 2002, came a quite unprecedented leap.

To outsiders, Shokin’s promotion from regional manager to the second most powerful prosecutor in the land looked magical. It was highly unusual for a candidate for one of the top public jobs not to have had significant managerial experience.

To insiders, the story was less mysterious.

In an interview in Kiev, the former chief prosecutor Sviatoslav Piskun, the man responsible for that promotion, revealed he hired Shokin after serious lobbying by Petro Poroshenko. At the time, the future president was a minor oligarch and deputy leader of the Our Ukraine faction in parliament.

Rudy Giuliani reads texts suggesting Kurt Volker and the state department were 'all over him' to get involved with Ukraine

“Poroshenko came to me with a clear request and the signatures of a hundred people in his faction,” says Piskun, who headed the prosecutor’s office between 2002-2005. “For the time I have known them, Shokin and Poroshenko were always extremely close. I must admit I never quite got to the bottom of exactly what their relationship was.”

Piskun insists that he never regretted hiring Poroshenko’s man, saying that Shokin showed himself to be a “capable” investigator. He mentioned Shokin’s success getting to the bottom of an investigation of the murders of journalists like Georgy Gongadze, who was found decapitated in woods outside Kiev in 2000. (Gongadze's family say those who ordered the killing were never brought to justice.)

“No one ever investigated as much as we did,” Piskun says. “And I doubt anyone will.”

It is not clear exactly when Shokin’s bond with Poroshenko was first struck. But from the early 2000s, the two men’s careers appeared to grow in tandem.

Following the Orange Revolution in 2004, Poroshenko took control of Ukraine’s national security council. Shokin got a second stint as deputy prosecutor.

In 2014, Poroshenko emerged from the Euromaidan revolution as president. And Shokin, at that point a pensioner, returned to the limelight as deputy prosecutor for the third time, becoming the main man a year later.

“They were together till the end,” says former deputy prosecutor Sakvarelidze. “You can be sure there were financial ties. In Ukraine, it is normal for a major oligarch to find his own prosecutor, his own judges and so on. Shokin was Poroshenko’s special deputy prosecutor. There was no surprise when Poroshenko brought him out of retirement.”

In a rare interview in 2015, Shokin insisted he had not asked Poroshenko for the top job. His former superior Piskun suggests that was not entirely true. “Shokin wanted the job,” the one-time chief prosecutor said, “though he wasn’t aggressive in lobbying for it.”

Lack of aggression was a description many would use for Shokin’s approach to the job in his third spell. Two of the people interviewed for this article described the former chief prosecutor as “lazy”, and uninterested in real investigations. Others noted a penchant for bonding with oligarchs over vodka in the bathhouse.

“He wasn’t exactly highly professional,” said one source, a current Kiev-based prosecutor who asked to remain anonymous. “Shokin would always sign documents without really looking at them. On the other hand, he’d let us get on with our jobs, and was quite democratic, which we all appreciated.”

Another source said Shokin’s tenure as Ukraine’s general prosecutor was “no more, but no less corrupt” than what went before it.

That, of course, was not a ringing endorsement. Since the fall of the USSR, the prosecutor general’s office has come to be considered one of the least trusted public institutions in Ukraine. In Soviet times, abuse of justice was ideological in nature, but the job was largely respected. Around the mid-1990s, corruption began to take over as the main driver. Over time, the institution degenerated into something resembling a legalised racket, sources say.

“When I joined we were doing 80 per cent honest endeavour, and 20 per cent corrupt,” says one prosecutor, who began his career in the late 1990s.

“Now things have switched, and it’s only 20 or 30 per cent honest. The main thing that matters is making the boss happy, and ultimately that means making the president happy. Everything else is for sale.”

The approach of Shokin’s office to the Burisma investigations fell into a well-practiced pattern of corruption, the anonymous prosecutor says. By the time of Biden’s intervention, there were no active investigations to speak of.

“If the idea was to get a result on the Burisma case, Shokin would have put his top people on it,” he says. “That didn’t happen. The aims were different.”

Investigations into Burisma, which only ever covered the period from before Hunter Biden’s involvement in the company, were finally settled in 2016. An audio recording purporting to be of Petro Poroshenko in conversation with another gas tycoon acting as a mediator, offered some clues as to the sequencing. In it, the two men talk about a “global solution” to Burisma’s problems: redirecting cashflows to Poroshenko’s companies.

Poroshenko’s spokespeople have described the recordings as fake, but not everyone is convinced.

“Neither Shokin nor Poroshenko wanted to investigate [Burisma owner Mykola​] Zlochevsky,” says Sakvarelidze. “They simply began a criminal case, arrested a few assets, and began negotiating with the corruptioneer for a bribe.”

Former chief prosecutor Sviatoslav says he gave Shokin his big break on the recommendation of Poroshenko (Oliver Carroll)

For activists, Shokin’s prosecutorship is remembered for its failure to secure convictions for crimes of the previous regime. These include the killing of more than 100 protesters during the Euromaidan revolution.

“Shokin impeded those fighting for justice,” said Vitaly Tytych, a lawyer representing the families of the victims. “It is wrong to call what he did investigations. Because if there is one thing Shokin never did it is investigate.”

Serhiy Horbatyuk, who headed the special investigation department which was eventually given responsibility for investigating the Euromaidan crimes, clashed with the leadership of the general prosecutor’s office.

“On Euromaidan, Shokin did not actively impede our investigations,” he says. “But he didn’t help them either. It seemed deliberate.”

By the time Joe Biden arrived in Kiev in December 2015 to issue his infamous ultimatum, Shokin had lost the support of all but 3.5 per cent of Ukrainians.

Many MPs were also clamouring for his dismissal.

First among them was Yehor Soboliev, then a reformist MP of the Samopomich faction and chair of the parliamentary anti-corruption committee. In July 2015, Soboliev pressed for a vote on Shokin’s ousting. The arithmetic was always against him, as the general prosecutor was a figure of the ruling coalition. But he came surprisingly close, collecting 127 signatures from a required 150. Several members of the ruling parties broke ranks to support his move.

“We were under no illusions,” Soboliev tells The Independent. “We saw how Shokin had made an art of dumping cases while pretending to investigate. How he was a symbol of ineffectiveness and stalling. How he was the embodiment of the post-Soviet prosecutor.”

In summing up, David Sakvarelidze used a similar formula.