Key players in special counsel Robert Mueller's Russian election interference probe

Since May 2017, the special counsel’s investigation into Russian interference in the 2016 election has been a constant presence in U.S. politics – a complex narrative that has included a rotating cast of characters and myriad plotlines.

Here is a roundup of the various figures who have been connected to the investigation at various points since President Donald Trump took office in January 2017.

Jeff Sessions

The two conversations that former attorney general Jeff Sessions had with Russian ambassador Sergei Kislyak – both of which happened during the campaign when Sessions was a very public supporter of Trump – were confirmed by the Department of Justice the day before he recused himself from any existing or future probes related to the presidential campaign. Without that recusal, Sessions would have been the one to oversee any such probes given his role as attorney general.

In a statement on March 2, 2017, Sessions said that over several weeks he met with "relevant senior career department officials" to discuss whether he should recuse himself and, "having concluded those meetings today, I have decided to recuse myself from any existing or future investigations of any matters related in any way to the campaigns for president of the United States."

The recusal made Sessions one of Trump’s favorite targets, with the president regularly blasting Sessions for failing to warn him that he might have to recuse himself.

In November, Sessions resigned at the request of President Trump and Sessions' chief of staff, Matthew G. Whitaker, a former U.S. attorney, took on the acting attorney general role. In February, William Barr, Trump's nominee and the attorney general under President George H.W. Bush from 1991 to 1993 was confirmed and sworn-in as attorney general. Barr now heads the Justice Department during a pivotal time, overseeing special counsel Robert Mueller's investigation into Russian interference of the 2016 presidential election.

Rod Rosenstein

After then-Attorney General Sessions recused himself from campaign related investigations, Deputy Attorney General Rod Rosenstein oversaw the Russia investigation. Rosenstein appointed Mueller as special counsel in May of 2017.

Since that time, Rosenstein has overseen Mueller’s probe, at times publicly defending the investigation from criticisms lodged by Republicans and the president. Rosenstein has appeared before Congress several times since taking the reins of the probe. Once Attorney General William Barr was sworn-in in February, Rosenstein was no longer in charge of overseeing Mueller's investigation.

ABC News reported that Rosenstein plans to leave the Department of Justice in mid-March.

James Comey

Former FBI Director James Comey was initially associated with the 2016 election after gaining notoriety for his public updates into the investigation into Hillary Clinton's use of a private email server during her tenure as secretary of state.

His role in the Clinton email investigation was cited in the letter that Deputy Attorney General Rod Rosenstein issued calling for his dismissal in May 2017.

"I remember just thinking, ‘This is a lie.’ The stuff about, you know, being fired because of the Hillary Clinton email investigation, that makes no sense at all," Comey told ABC News Chief Anchor George Stephanopoulos in April 2018. "And then, of course, I quickly saw on the news that you know, the White House saying that the FBI was in tatters and the workforce -- it was relieved that I was fired. More and more lies. And so I was worried about the organization, worried about the people."

Right after he was dismissed, the White House publicly denied that Trump was considering the handling of the FBI investigation into his campaign’s possible ties with Russia when he fired Comey.

But then, a couple of days later, Trump himself appeared to contradict that in an interview with Lester Holt of NBC News.

“When I decided to just do it, I said to myself, I said, 'You know, this Russia thing with Trump and Russia is a made up story, it's an excuse by the Democrats for having lost an election that they should have won,'" Trump told Holt.

Matthew Whitaker

Matthew Whitaker was named as the acting-attorney general on Nov. 8, 2018.

Though Rosenstein had been overseeing the Russia probe during Sessions' tenure because of his recusal, that then shifted to Whitaker when he became the acting attorney general. Whitaker had previously criticized the probe – a point of contention for Democrats when he appeared at a recent hearing before the House Judiciary Committee.

Whitaker defended his performance saying that he had "not interfered in any way with the special counsel's investigation," but he refused to say whether he had discussed the Michael Cohen case with President Trump.

In March, shortly after Bill Barr was confirmed as attorney general, ABC News reported that Whitaker left the Justice Department.

Bill Barr

Trump named Bill Barr as his new pick for attorney general in December of 2018, exactly one month after the departure of Jeff Sessions. He previously served as the nation’s top law enforcement official during former President George H.W. Bush’s administration.

Barr attempted to make it clear to wary Democrats on the Senate Judiciary Committee during his confirmation hearing that he will not unnecessarily or inappropriately interfere with the Russia investigation, but he did not commit to a full public release of Mueller's report as Democrats wanted.

At one point during his opening remarks in January, Barr noted how he has known Mueller “for 30 years” and how they “worked closely together” during his earlier time at the Department of Justice.

“When he was named special counsel, I said his selection was ‘good news’ and that, knowing him, I had confidence he would handle the matter properly. And I still have that confidence today,” Barr said of Mueller during the hearing.

At an earlier hearing, Barr said that he thinks “it is in the best interest of everyone…. that this matter be resolved by allowing the special counsel to complete his work.” Barr was confirmed by the Senate and sworn in in February.

Paul Manafort

In the years prior to joining the Trump orbit, Manafort’s political consulting work focused largely abroad, working for Ukraine's since-toppled President Viktor Yanukovych, and his political party, the Party of Regions, starting in 2006 and continuing until at least 2010.

In the United States, Manafort, 69, was known in Republican Party politics for decades – having worked for Presidents Ronald Reagan and George H.W. Bush – before joining the Trump campaign in March 2016 as the campaign’s convention manager and then getting promoted to campaign chairman two months later.

Manafort was found guilty on eight counts of financial crimes as part of the first major prosecution won by the team led by special counsel Robert Mueller's team.

On the eve of a second trial in Washington, DC, in September, Manafort pleaded guilty to two counts of conspiracy and agreed to cooperate with prosecutors.

But that plea deal was short-lived. The special counsel’s office accused Manafort of lying to prosecutors after agreeing to cooperate, which they say amounted to a breach of his agreement. Defense counsel claimed Manafort did not intentionally lie, but the federal judge overseeing his case sided with prosecutors.

He has been behind bars since June after the judge in his D.C. case revoked his bail amid allegations of witness tampering.Sentencing dates in both courts have been set and delayed after the Office of Special Counsel moved to set aside the plea deal based on the allegations that Manafort had lied.

The special counsel's office has since filed a sentencing memo for Manafort in Virginia, in which prosecutors agreed with the findings of an independent pre-sentence report, which calculated that Manafort’s crimes call for a prison sentence of up to 25 years.

Michael Flynn

The first and only Trump White House aide to plead guilty to a crime in special counsel Robert Mueller's investigation into Russian influence operations targeting the 2016 presidential election was a decorated retired military intelligence officer, Army Lt. Gen. Michael Flynn, who the president had insisted serve as his White House national security adviser.

In prosecuting Flynn for lying to FBI agents, a felony, about his discussions with Russian Ambassador Sergey Kislyak about U.S. sanctions and other subjects, prior to Trump being sworn in as the 45th U.S. president, Mueller not only secured a key witness but he also sent a message to other witnesses in the probe to cooperate fully – though several more Trump campaign aides later admitted to lying to the FBI anyway.

Rick Gates

Gates was a Trump campaign aide who was brought into the then-future-president’s orbit by his longtime boss Manafort. Gates served as the government’s star witness in their trial against Manafort, and Gates admitted that they shielded millions of dollars in offshore accounts to keep it away from tax collectors.

Gates was charged in two separate federal courts in connection to financial crimes, unregistered foreign lobbying and on allegations that he made false statements to federal prosecutors.

Gates pleaded guilty in Washington, D.C., in February 2018 on counts of conspiracy against the United States and lying to federal prosecutors.As part of his plea agreement, he avoided prosecution on a slew of financial charges in the Eastern District of Virginia that included assisting in the preparation of false income taxes, bank fraud, bank fraud conspiracy and false income taxes.

His charges are intimately tied to those of Manafort. In the Eastern District of Virginia, the two were indicted jointly.

Konstantin Kilimnik

Kilimnik is a longtime business associate of Paul Manafort’s who was responsible for overseeing the Kiev, Ukraine office of Manafort’s lobbying firm.

In August of 2016, shortly after the Republican National Convention, Manafort, his business associate Rick Gates, and Kilimnik met at the Grand Havana Room, a cigar club in New York. In a closed-door hearing in Manafort's case in early February, special counsel prosecutor Andrew Weissmann told the judge that the meeting goes "very much to the heart of what the special counsel's office is investigating."

Earlier Manafort indictments refer to a "Person A" who was identified by sources as Kilimnik. However, he was formally identified in a third superseding indictment against him and Manafort, which accused Kilimnik of conspiracy to obstruct justice and obstruction of justice.

The charges he faces are linked largely to an attempt to relay messages from Manafort in his alleged attempt to tamper with potential witnesses in the case against him.

Kilmnik has been identified as having ties to Russian intelligence. Though he's been indicted, he has not entered a plea. He remains out of reach of U.S. law enforcement.

Michael Cohen

One of the longest-serving members of the Trump inner circle who has come under scrutiny is Michael Cohen, Trump's former personal attorney and longtime fixer.

Cohen's activity during the campaign came into the national spotlight in reference to payments made to two women who alleged that they had affairs with Trump, affairs Trump has denied.

In August 2018, Cohen pleaded guilty to eight counts, including two related to illegal campaign contributions "in coordination and at the direction of a candidate for federal office." The charges were brought by federal prosecutors in the Southern District of New York.

He was sentenced to three years in prison for charges including campaign finance violations, tax evasion, and lying to Congress.

According to court documents, Cohen admitted that he made the misstatements about the “Moscow Project” – the Trump Organization’s efforts to “pursue a branded property in Moscow” in an August 2017 letter to the House and Senate intelligence committees, which were conducting inquiries into alleged collusion and Russian interference.

Ultimately, the proposed plan to build a Trump tower in Moscow was scrapped.

Cohen has cooperated with Mueller and participated in multiple interview sessions with investigators from the office of special counsel Mueller, totaling more than 40 hours, sources told ABC News.

Roger Stone

Given his decades-long role in Republican politics, Stone was one of the better-known members of the extended Trump network of campaign advisers.

His colorful history – from the tattoo of former President Richard Nixon that he has on his back, to being a self-described “dirty trickster in Republican politics for decades” made him one of the most visible politicos in Trump’s orbit.

Stone was arrested in January after Mueller filed a seven-count indictment against him as part of the ongoing probe into Russia interference during the 2016 presidential election.

The special counsel leveled against Stone, 66, five counts of lying to Congress, one count of obstruction of an official proceeding, and one count of witness tampering. He has pleaded not guilty and the federal judge overseeing his case has since issued a gag order on all parties involved in the case – including the gregarious Stone.

Carter Page

Page was a foreign policy adviser to the Trump campaign and came under FBI scrutiny during the campaign itself because according to the FISA application, the FBI believed he had been the subject of targeted recruitment by the Russian government, according to an application with the Foreign Intelligence Surveillance Court. Page is alleged to have had “established relationships with Russian Government officials, including Russian intelligence officers.”

Page told Stephanopoulos in February 2018 that there was "no basis" for the FBI to eavesdrop on him and called their investigation “just complete ridiculousness.”

Felix Sater

The Soviet-born American businessman, who, along with Michael Cohen, held discussions with Russians about a possible Trump tower in Russia used to describe himself as a “senior advisor to Donald Trump. Sater is also a convicted felon and one-time stock scammer who promised to "get all of Putin's team to buy in" on a proposed plan to build "Trump Tower Moscow" in the heat of the presidential campaign.

Donald Trump Jr.

One known contact that several members of the Trump team had with Russians during the campaign came through a meeting arranged through pop music promoter Rob Goldstone with the president’s son, Donald Trump Jr, and a Russian attorney in Trump Tower on June 9, 2016.

Accounts of the motive for the meeting, the nature of the meeting and the attendees involved changed after The New York Times first reported about the meeting in July 2017. The initial statement about the meeting – which it was later determined to have been drafted by President Trump – said that the meeting was about adoption policy.

But as emails released by Trump Jr. show, he believed he was meeting the lawyer, Natalia Veselnitskaya, to obtain damaging information about his father's then-Democratic rival Hillary Clinton. In addition to Trump Jr., two other key Trump campaign officials attended the meeting -– then-chairman Paul Manafort and campaign adviser and Trump son-in-law Jared Kushner.

In a statement on behalf of Donald Trump Jr., Trump Organization attorney Alan Futerfas previously said, “Donald Trump Jr. has been professional and responsible throughout the Mueller and Congressional investigations. We are very confident of the accuracy and reliability of the information that has been provided by Mr. Trump, Jr., and on his behalf.”

Jared Kushner

Kushner, who married into the Trump family when he wed Ivanka Trump, was an ever-present member of the Trump campaign and remains a key senior adviser in the administration.

Because of his intimate role in the campaign, as well as his presence at the Trump Tower meeting with the Russian lawyer, questions about his contacts with Russians and knowledge of others’ were inevitable.

In July 2017, Kushner became the first Trump family member questioned by the Senate Intelligence Committee as part of the investigations into Russian meddling. He released a statement before the closed-door session denying any collusion with Russia.

"Let me be very clear: I did not collude with Russia, nor do I know of anyone else in the campaign who did so. I had no improper contacts. I have not relied on Russian funds for my businesses," Kushner said.

ABC News’ Mike Levine, John Santucci, Cheyenne Haslett, Benjamin Siegel, Lucien Bruggeman, Ali Dukakis, Allison Pecorin, Luke Barr, Trish Turner, Katherine Faulders, Lauren Pearle, Pete Madden, Matthew Mosk, Adam Kelsey, Jonathan Karl, Pierre Thomas, Justin Fishel, Devin Dwyer, Karma Allen, Lee Ferran, James Gordon Meek, Patrick Reevell, Meghan Keneally and Avery Miller contributed to this report.