(CNN)The Justice Department and both chambers of Congress are all now investigating alleged Russian attempts to meddle in the 2016 elections and whether President Donald Trump's associates colluded with Moscow -- an ever-evolving saga that is showing no signs of slowing down despite the firing of the man who long found himself spearheading the probe, now-former FBI director James Comey.
Who's who in Trump-Russia saga
CNN has compiled a list of the growing and diverse cast of characters at the start of a critical week of hearings for Senate investigators looking into Russia's actions and its possible ties to Trump associates.
Several US lawmakers and agency heads have emerged as visible, and at times controversial, figures in the investigations into connections between individuals in Trump's orbit and Russian hacking of Democratic Party groups including the Democratic National Committee and Clinton campaign adviser John Podesta.
Robert Mueller -- The Justice Department named Robert Mueller as special counsel to oversee the department's investigation into Russian meddling in the 2016 election after the firing of Comey on May 9. The former FBI director has a long history with investigations and prosecutions. Mueller was former Comey's predecessor.
The longtime litigator was the second-longest FBI director in history, only behind iconic and controversial director J. Edgar Hoover. Congress passed legislation in 2011 to extend Mueller's term from the usual 10 years, giving him a 12-year tenure.
Mueller, 72, oversaw the FBI from September 4, 2001, just days before the September 11, 2001, terrorist attacks, until September 4, 2013.
He is widely seen as a nonpolitical, dogged investigator, respected on both sides of the aisle. The extension of his term passed the Senate 100-0, and he was also initially confirmed in 2001 unanimously, 98-0.
James Comey -- The now-former FBI director was fired abruptly by Trump, but seemed to have a knack for finding himself in the middle of high-profile political controversies while serving as the nation's top law enforcement officer. Months after weathering criticism from both parties over his handling of the investigation into Hilary Clinton's use of a private email server while secretary of state, Comey once again is front and center in another political storm. Most recently, he dropped a bombshell before the House Intelligence Committee when he told lawmakers last week that the bureau was investigating not only Russian hacking and other alleged interference in the 2016 vote, but whether there was any coordination between Trump figures and Moscow as part of its intrusions.
Mike Rogers -- Late last year, Rogers was simultaneously a candidate to be promoted to Director of National Intelligence under President-elect Trump and on the hot seat to be fired as director of the National Security Agency by then-President Barack Obama. Eventually, Rogers remained in his role as the director of the NSA under Trump and now finds himself among those agency heads testifying before Congress as an authority on cybersecurity as it relates to hacks by suspect Russian-relate groups.
Rogers played a key role in last week's House hearing with Comey when he joined the FBI director in refuting Trump's claim that Obama had had his phones tapped during the campaign. He in particular batted down the notion that the Obama administration requested that the British eavesdrop on Trump, an unfounded assertion made on Fox News cited by the Trump White House.
Sally Yates -- A holdover from the Obama administration, the most memorable moment of Yates' short tenure as acting Attorney General may have been her firing in the early days of the Trump administration after she refused to implement the President's orders barring travelers from seven Muslim-majority countries.
Yates also briefed Trump's White House counsel on former national security adviser Michael Flynn's meeting with Russian ambassador Sergey Kislyak, communications that ultimately led to Flynn's resignation. Her scheduled testimony before the House Intelligence Committee on ties between Russian agents and Trump campaign officials was abruptly cancelled by committee Chairman Devin Nunes. The White House rejected allegations that it had sought to prevent Yates from testifying.
James Clapper -- The director of national intelligence under Obama has never been shy in offering criticism of Trump, clashing with him over the latter's public disparagement of intelligence officers, wiretapping allegations and views on Russian hacking. Clapper, along with Comey and then-CIA Director John Brennan, briefed Trump on Russian hacking during the election campaign just hours after the President-elect doubled down on his dismissal of the threat as an artificial and politically driven controversy, calling it a "witch hunt." He has also had been invited to testify by Congress.
John Brennan -- Nearly three years ago, John Brennan, acting CIA director at the time, found himself apologizing to the Senate intelligence committee and acknowledging that the CIA had spied on senators' computers after previously vehemently denying the claims. Now, Brennan, who has been out of the role since January, is testifying about his own concerns about espionage from Russia via possible contacts with the Trump campaign.
Dan Coats -- Less than two months into his tenure as Director of National Intelligence, Dan Coats is being thrust into the public spotlight -- asked to testify before Congress amid an investigation into Russian meddling during the 2016 election.
It is a potentially precarious situation for the former US lawmaker and diplomat who is now serving as Trump's principal adviser on intelligence matters and head of US intelligence efforts.
Confirmed to his new post in March, Coats now finds himself involved in an investigation looking into possible collusion between a foreign power and members of the campaign that helped elect the man who picked him for the post.
Mike Conaway -- Rep. Mike Conaway has been given the reins to the House intelligence committee's fractured Russia investigation following chairman Rep. Devin Nunes' announcement that he is temporarily stepping aside --- but who is the man now tasked with getting things back on track after weeks of partisan conflict?
A seven-term Republican representing Texas' 11th Congressional District, Conaway is the chairman of the agriculture committee in addition to serving as a member of the intelligence committee and Armed Services Committee.
He has also chaired the House ethics committee during his time in Washington.
A member of the House intelligence subcommittee that oversees the National Security Agency and CIA, Conaway has expressed skepticism over the intent of Russian meddling in the 2016 election.
Devin Nunes -- The man once charged with leading the House's investigation into possible connections between Trump associates and Russia's hacking of the 2016 election stepped asied after becoming the focus of controversy. Nunes worked on Trump's transition team, publically supported Flynn just hours before his resignation as national security adviser and downplaying Trump's wiretapping allegations against Obama by suggesting they shouldn't be taken literally.
Nunes particularly provoked Democrats after he disclosed evidence to the press and White House -- before informing Democrats on his committee -- that the Trump team's communications may have been picked up in "incidental" collections by US surveillance of conversations with foreign nationals who were being lawfully monitored. That was seen as a move to bolster Trump's claims of having been wiretapped. The news Monday that Nunes met his source on White House grounds the day before he briefed Trump sparked the latest round of partisan fighting and has left investigators unable to continue right now. Now, Nunes is facing calls to step down as chairman amid questions as to whether he can conduct an impartial investigation. He told CNN Tuesday morning, however, that he was "moving forward" with the investigation.
Adam Schiff -- The Democratic "yin" to Nunes' Republican "yang," Schiff is his party's most senior member on the House Intelligence Committee and has been one of the most visible lawmakers on the Russia investigation. Though the committee has historically been one of the more discreet on Capitol Hill, Schiff hasn't held back his criticism of Trump or, increasingly, the committee chairman. On Monday, Schiff called on Nunes to recuse himself from the investigation in a stunning split between the two top investigators of a committee with a reputation for bipartisanship. Schiff has repeatedly maintained he's seen additional evidence that is more than circumstantial proof of collusion between Trump aides and Russian entities.
Elijah Cummings -- The representative from Maryland is the ranking Democrat on the House Oversight Committee. Cummings was one of the first lawmakers to call for an investigation into Russian meddling in the US election. Cummings wrote a letter to committee chairman Rep. Jason Chaffetz in November 2016 calling for a bipartisan commission, similar to the one that investigated the 9/11 attacks, and the Democratic effort to have an independent investigation is only gathering steam as the acrimony on Capitol Hill rises.
Cummings has also gone beyond calls for Nunes to recuse himself, suggesting he be investigated after his comments disclosing the surveillance that may have picked up conversation of Trump associates. And he has also sharply denounced Flynn, brandishing emails that show the former national security adviser was paid by Russian entities for a trip there during the campaign, raising legal and regulatory questions.
Richard Burr -- The North Carolina Republican and chairman of the Senate Intelligence committee is leading a separate investigation into Russian efforts to tamper with the US election. So far it has been a low-key process, as he's stayed out of the limelight while interviewing witnesses in private. Some of that will change Thursday, when the Senate Intelligence Committee hosts its first public hearing for its Russia investigation.
Investigations by the FBI and congressional committees have included several aides to the Trump campaign and their communication with key foreign entities and, in some cases, Russian operatives. Others have cropped up in headlines because of their dealings with the longtime US adversary. Several of these individuals have volunteered to testify before House and Senate Intelligence Committees in recent days to clear up questions about their actions and associations.
Marc Kasowitz -- The prominent New York lawyer expected to represent Trump throughout the widening Russia probes has professional connections of his own to Moscow, which could create yet another public-relations problem for the White House.
Kasowitz, who has been Trump's go-to lawyer for years on both personal and business matters, is defending a Russian bank, OJSC Sberbank, in an ongoing lawsuit in US court. He also represents a company controlled by a Russian billionaire, Oleg Deripaska, who has close ties to the Kremlin.
Kasowitz' clients with Russian ties may not pose any legal conflicts of interest as he prepares to help Trump navigate an investigation that the President calls "a witch hunt." But the optics of the situation -- a lawyer with Russian-linked clients representing a President whose campaign is being investigated for alleged collusion with Russia -- could make a messy situation for Trump even messier.
Michael Flynn -- Flynn has courted controversy since before he became an early supporter of Trump's campaign. In 2014, he was pushed out as director of the Defense Intelligence Agency in Obama's Pentagon. Flynn said it was because he raised alarm bells on Islamic terrorism, but four US officials serving at time told CNN it was because of his contentious management style.
His reputation for outspokenness and criticizing Washington figures led to raised eyebrows inside the Beltway when Trump tapped him as national security adviser. His tenure in any case didn't last long, as he resigned after acknowledging that he misled Vice President Mike Pence about the nature of his communications with the Russian ambassador in Washington, Sergey Kislyak. He had initially denied that they had discussed sanctions recently imposed by the Obama administration. It is illegal for unauthorized private citizens to negotiate with foreign governments on behalf of the US, though the FBI has said that it has no intention of bringing charges against Flynn. At the time, Flynn did not hold a public office in the US government which technically qualifies him as a private citizen
His financial ties with Russia and other foreign countries have also attracted attention, including the emails obtained by Cummings showing that he was paid by a state-run Russian TV outlet from which he had originally denied receiving funds.
Paul Manafort -- A Republican strategist and longtime Washington operator, Manafort joined Trump's campaign team last spring and was elevated after campaign manager Corey Lewandowski was fired in June. But with just under three months to go until the presidential election, Manafort resigned amid questions over his campaign role and extensive lobbying history overseas, particularly in Ukraine, where he represented pro-Russian interests.
Manafort's connections to Russia faced fresh scrutiny earlier this year after current and former US officials told CNN that high-level Trump campaign advisers, including Manafort, regularly communicated with Russians known to US intelligence. Manafort called the allegation "100% not true" and said he didn't "remember talking to any Russian officials, ever."
Manafort has recently turned over hundreds of pages of documents to the Senate intelligence committee.
Jared Kushner -- The 36-year-old businessman-turned-political operative played a crucial role in his father-in-law's presidential campaign and has carved out a role for himself as one of Trump's key White House aides. After amassing billions of dollars in properties over his decade in the New York real estate market, he now finds himself frequently assisting the President in matters of foreign policy.
That has led to questions in certain arenas, including a recently disclosed meeting he held in December with a Russian banker appointed by President Vladimir Putin. The White House maintains that Kushner met with the banker in his role as a Trump adviser while the bank said it met with Kushner as a private developer.
Kushner has volunteered to testify before senators because of his role in arranging meetings between top campaign advisers and Kislyak, the Russian ambassador.
Carter Page -- Page worked for seven years as an investment banker at Merrill Lynch, which his biography said took him to London, New York and Moscow for three years in the mid-2000s, before Trump last year listed him as a foreign policy adviser in response to a question from The Washington Post.
Page has regularly espoused views at odds with much of the foreign policy community in Washington, in particular questioning the US approach toward Russia and called for warmer relations between the two countries.
His reported meeting with Kislyak during the Republican convention in Cleveland is one of his interactions with Russian officials that has caught the attention of the FBI. Page has denied any wrongdoing and volunteered Friday to speak to the House Intelligence Committee about his role in Trump's campaign. Page, who the White House has said was only loosely connected to the Trump campaign, emphasized last week that he was not a campaign insider.
J.D. Gordon -- A former Pentagon spokesman under Defense Secretaries Donald Rumsfeld and Robert Gates, Gordon contributed to a variety of media outlets before working as a national security adviser to the Trump campaign.
Gordon disclosed earlier this month that he was among the Trump advisers who had met with Kislyak during the Republican National Convention in Cleveland in July. Gordon told CNN that he told Kislyak that he would like to improve relations with Russia. Gordon added that at no time did any inappropriate chatter come up about colluding with the Russians to aid the Trump campaign.
Roger Stone -- The eccentric former Trump adviser and self-described, master of political dark arts has been labeled as the "dirty trickster" of delegate fights. He has worked with the campaigns of Richard Nixon, George H. W. Bush and Ronald Reagan.
Stone repeatedly claimed throughout the final months of the 2016 campaign that he had backchannel communications with WikiLeaks founder Julian Assange and that he knew of the group's forthcoming document dumps, which disseminated the materials hacked from the Democrats. Later, Stone walked back those tweets. His attorney told CNN on Friday that he is willing to speak to the House Intelligence Committee -- preferably in public -- but maintains he has done nothing wrong. Wikileaks also denies any connection with Stone.
Roger Stone also has been forced to defend contacts with hacker Guccier 2.0 on Twitter. While Stone said his messages to the hacker alias are of no consequence, he is the first person in Trump's orbit to have acknowledged any contact with a hacker -- not to mention one that claimed responsibility for hacking the DNC.
Michael Cohen -- Trump's personal lawyer has been a staunch defender of his client, often serving as a media surrogate during the campaign. During a CNN interview in February, Ukrainian lawmaker Andrii Artemenko said he had discussed a pro-Russian peace plan for Ukraine with Cohen over dinner in January. Ukraine would vehemently oppose the idea that the White House would consider formalizing Russian control of Crimea. Cohen told CNN that they never discussed a peace plan and the White House has flatly denied any knowledge of the proposal.
Connections between Trump campaign aides and notable foreigners have fueled suspicions of possible coordination with Russia. Specifically, the US officials told CNN last week that it has information that indicates Trump associates communicated with suspected Russian operatives to possibly coordinate the release of information damaging to Hillary Clinton's campaign.
Sergey Kislyak -- The Russian ambassador to the US is seemingly ubiquitous around town, having gained extensive experience during a career spanning both the Soviet and Russian Federation eras. Not only did the veteran diplomat meet multiple times with Flynn, drawing scrutiny, but his meetings with then-Sen. Jeff Sessions led to the attorney general recusing himself from any potential investigations.
Kislyak has also held several meetings -- or at least photo-ops -- with Democrats. House Minority Leader Nancy Pelosi (who has joined the calls for Nunes to recuse himself) claimed to have never met with Kislyak, but a photo surfaced showing the two individuals in the same room. Current and former US intelligence officials TELL CNN that Kislyak is a top spy and recruiter of spies, an accusation that Russian officials have dismissed.
Julian Assange -- The founder of Wikileaks, the self-styled "radical transparency" organization with the stated goal of exposing the secrets of the powerful, Assange has cast a wide, blurry shadow over the center of US politics from his seclusion in the Ecuadorian Embassy in London, where he remains holed up to avoid facing sexual assault charges in Sweden and a potential extradition to the United States.
Assange spearheaded the release of nearly 20,000 internal DNC emails last July, which US intelligence bodies unanimously concluded were hacked by the Russians. WikiLeaks also began to serially release emails from Podesta, the Clinton campaign chairman, in October. WikiLeaks has denied that Russia was the source for its disclosures, and the Russian government has emphatically denied any connection with the theft as well.
Guccifer 2.0 -- The hacker otherwise known as "Guccifer 2.0" burst into the national conversation after claiming responsibility for a hack of the Democratic National Committee last year. US officials believe with "high confidence" that "Guccifer 2.0" was actually a front for Russian military intelligence and was part of the effort to influence America's elections.
Roger Stone has been forced to defend contacts with the online persona via Twitter. While Stone said his messages to the hacker alias are of no consequence, he is the first person in Trump's orbit to have acknowledged any contact with a hacker -- not to mention one that claimed responsibility for hacking the DNC.
Christopher Steele -- A former officer with MI6, the UK's foreign intelligence service, Steele compiled a dossier of unsubstantiated allegations related to Trump's personal and business ties to Russia before he became president. Steele initially had been hired by a Washington research firm working on behalf of Trump's political opponents -- initially in the Republican primary and then later Democrats.
The FBI obtained a version of Steele's dossier last summer and investigators compared it to some of their own work related to Russia's attempts to influence the US election.
His file contained claims that Russian operatives had compromising personal and financial information about Trump. Trump has consistently denied the claims, dismissing them as "phony" in January, though Schiff and others drew on some of them in the Comey-Rogers hearing last week. US investigators said they have corroborated some of the communications in the dossier, but CNN has not been able to verify many of the specific allegations in the documents.