Dec. 1 (UPI) -- It's the biggest question of Donald Trump's presidency: Did members of his campaign collude with the Russian government to sway the 2016 election?
U.S. intelligence agencies announced in October that they agree Moscow was responsible for hacking Democratic National Committee computers as well as those of other Democratic figures and organizations.
The hackers forwarded the information they obtained to WikiLeaks, some of which was seen as damaging to campaign of Trump rival Hillary Clinton.
What role, if any, Trump or his associates played in the hacking has prompted four investigations -- one by the FBI, one in the House and two in the Senate -- which collectively Trump has labeled a "witch hunt."
Attempts to answer the question have also prompted a new one -- whether Trump has obstructed investigations into the matter.
Here are the key players and how they're involved:
President Donald Trump
Trump has characterized allegations that his campaign colluded with Russian efforts to meddle in the election as a "witch hunt."
Though he said he wasn't involved in the DNC hacking, in July 2016, Trump said he hoped Russia would find 30,000 emails missing from Hillary Clinton's private email server during her time as secretary of state.
"Russia, if you're listening, I hope you're able to find the 30,000 emails that are missing," he said during a press conference in Doral, Fla.
Trump later tweeted that if Russia did have the emails, they should share them with the FBI.
Clinton's campaign accused Trump of actively encouraging "a foreign power to conduct espionage against his political opponent." Trump said he was only joking.
Though he often praised Russian President Vladimir Putin during his campaign, Trump repeatedly denied meeting with him prior to their first official face-to-face at the G20 summit in Berlin in July 2017.
Prior to his campaign for president, Trump had numerous business dealings with Russian companies. About one-third of the units on the most expensive floors of Trump Tower in Manhattan were sold to people or companies connected to Russia and neighboring states by 2004.
Just before ground broke on the building, Russia defaulted on $40 billion in domestic debt, the ruble plummeted and many Russian millionaires invested in U.S. real estate as a safe place for their money.
Trump and his children have traveled to Russia number of times for business deals, and though he applied for trademarks there, he never purchased any real estate or opened hotels in Russia.
In a September 2015 interview on The Hugh Hewitt Show, Trump said he made contacts with powerful people in Russia.
"I was with the top-level people, both oligarchs and generals, and top of the government people. I can't go further than that, but I will tell you that I met the top people, and the relationship was extraordinary," he said.
Trump and former White House press secretary Sean Spicer have said he has no financial or business connections to the country.
Some members of Congress have questioned whether Trump obstructed the FBI's Russia probe when he allegedly asked former director James Comey to drop the investigation into former national security adviser Michael Flynn.
Flynn became the first former Trump administration official to be charged in the special counsel probe on Dec. 1, 2017. He pleaded guilty to one count of making a false statement to the FBI regarding conversations he had with Russian Ambassador Sergey Kislyak.
The plea could indicate Flynn is cooperating with the special counsel investigation and could provide beneficial information.
Trump forced Flynn to resign as his national security adviser Feb. 13, 2017, for misleading Vice President Mike Pence about a meeting he had with Kislyak during the transition period.
In his resignation letter, Flynn said he may have discussed policy matters and potential sanctions by the Obama administration with Kislyak, topics he later told Pence were not discussed.
Trump said he only fired Flynn because of the lack of disclosure to Pence, and supported his national security adviser's contacts with Russians during the transition. Comey testified in June that Trump implied he wanted the FBI to "let go" of its investigation into Flynn. Trump has denied the allegation.
In December 2015, Flynn sat at a table with Putin at a gala for Russia's state-owned news outlet, RT, and made an appearance on the television network. He made $65,000 that year from companies linked to Russia, but omitted the payments on his security clearance renewal paperwork in January 2016.
In April, Flynn filed revised financial disclosure forms revealing payments from three Russian companies with ties to the Kremlin shortly before he joined the Trump campaign.
After initially invoking the Fifth Amendment, Flynn said he would comply with a Senate intelligence committee subpoena for personal and professional documents related to his dealings with Russia.
Trump fired Comey as director of the FBI on May 9, less than four years into his 10-year term. Trump initially said he fired him because of his conduct in the FBI investigation into Clinton's emails.
Later, Trump attributed the dismissal to the active FBI investigation into whether the Trump campaign colluded with Russian efforts to sway the presidential election. Days before he was fired, Comey had asked the Justice Department for more resources and staff for the investigation.
"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,'" Trump said in an interview at the time.
On June 8, Comey testified before the Senate intelligence committee and said he wrote detailed memos after every discussion he had with Trump. Comey said that shortly after Trump fired Flynn, the president asked him to stop the Flynn investigation.
"I hope you can see your way clear to letting this go, to letting Flynn go," Comey testified that Trump said.
Comey said he didn't interpret that to mean that Trump wanted the entire Russian investigation dropped.
Attorney General Jeff Sessions recused himself from heading the Justice Department's Russia investigation after it was revealed he didn't disclose meeting with Kislyak twice while he was a surrogate of the Trump campaign.
During his confirmation hearing on Jan. 10, Sessions said he was not aware of anyone affiliated with the Trump campaign communicating with the Russian government.
"I have been called a surrogate at a time or two in that campaign and I didn't have -- did not have communications with the Russians, and I'm unable to comment on it," he said.
Sessions later said his meetings were part of the normal course of duty for his job as a U.S. senator and he never discussed campaign-related matters. To avoid the appearance of a conflict of interest, he stepped away from the investigation, a move Trump has since criticized.
"Jeff Sessions takes the job, gets into the job, recuses himself, which frankly I think is very unfair to the president," Trump told The New York Times in July. "How do you take a job and then recuse yourself? If he would have recused himself before the job, I would have said, 'Thanks, Jeff, but I'm not going to take you.' It's extremely unfair -- and that's a mild word -- to the president."
After Sessions' recusal, Deputy Attorney General Rod Rosenstein appointed former FBI Director Robert Mueller as special counsel to lead the FBI investigation into Russia.
Donald Trump Jr.
Most of the focus on the president's oldest son's involvement with Russia has been on his June 2016 meeting with a Kremlin-linked lawyer who said she had damaging information about Clinton.
A total of eight people attended that meeting, which started with an email from British music publicist Rob Goldstone to Trump Jr. In it, Goldstone offered to arrange a meeting between Trump Jr. and Natalia Veselnitskaya, whom he described as a "Russian government attorney." Goldstone said she wanted to give Trump Jr. information about Clinton as "part of Russia and its government's support for Mr. Trump."
Trump Jr. agreed to go, saying, "If it's what you say, I love it, especially later in the summer."
Trump Jr. said Veselnitskaya made "vague" and "ambiguous" statements that "made no sense" related to alleged information she had that individuals connected to Russia were funding the Democratic National Committee in support of Clinton.
He said Veselnitskaya's "true agenda" was to discuss the U.S. adoption of Russian children and the Magnitsky Act.
In addition to Trump Jr. and Veselnitskaya, six others were at the meeting: Goldstone; Ike Kaveladze, the vice president of a Russian real estate company; Paul Manafort; Jared Kushner; Rinat Akhmetshin, a Russian-American lobbyist who served in a counterintelligence unit of the former Soviet military; and Anatoli Samochornov, a former State Department employee acting as a translator for Veselnitskaya.
On Sept. 7, Trump Jr. had a private meeting with the Senate Committee on the Judiciary. He said he attended the Trump Tower meeting because Veselnitskaya promised "information concerning the fitness, character or qualifications of" Clinton.
Senior White House adviser and President Trump's son-in-law Jared Kushner said he met four times with Russian officials.
In June 2016, he was one of eight people in attendance at the meeting between Trump Jr. and a Kremlin-linked Russian lawyer.
In December 2016, he met with Kislyak and Flynn at Trump Tower in Manhattan. The White House said they spoke about "potentially establishing a more open line of communication in the future."
The same month, he also met with Sergey Gorkov head of Russian state investment bank Vnesheconombank.
On July 24, 2017, Kushner testified before the Senate intelligence committee that his meetings with Russians the year before were "proper" and not an attempt to collude with them to win the election.
Kushner has come under scrutiny for not disclosing the meetings on his SF-86 questionnaire, which he submitted as part of his security clearance. He said his assistant submitted the form before he had a chance to review it.
A federal judge placed Paul Manafort on house arrest Oct. 30, 2017, after he pleaded not guilty to the first series of charges brought by Mueller's investigation. He posted $10 million bond.
A 31-page indictment charged Manafort with conspiracy, money laundering, tax fraud, failure to file reports of foreign financial assets, serving as an unregistered foreign agent and giving false and misleading statements under the Foreign Agents Registration Act.
Manafort resigned as Trump's campaign chairman in August 2016 after The New York Times reported a Ukrainian government corruption probe found Manafort received nearly $13 million off the books from a pro-Russian Ukrainian political party. In June 2017, when Manafort registered as a foreign agent after the fact, he reported making more than $17 million from the Party of Regions.
Within the first month of Trump's presidency, U.S. intelligence agencies said they were investigating intercepted phone calls between Manafort and Russian intelligence agents. Manafort said he didn't realize they were intelligence agents.
Manafort also was one of eight people in attendance at a meeting between Trump Jr. and a Kremlin-linked Russian lawyer.
Manafort was scheduled to testify before the Senate Committee on the Judiciary in July 2017, but the committee dropped its subpoena after he spoke with members of the Senate intelligence committee and gave them documents on July 25.
Former Trump campaign aide Rick Gates, along with Manafort, faced one of the first indictments approved by a grand jury in the Mueller probe. A judge placed him on house arrest Oct. 30, 2017, after he pleaded not guilty to a series of charges including conspiracy, money laundering, tax fraud, failure to file reports of foreign financial assets, serving as an unregistered foreign agent and giving false and misleading statements under the Foreign Agents Registration Act. He posted $5 million bond.
Gates is accused of transferring more than $3 million from offshore accounts.
Though Manafort was ousted from the Trump campaign in 2016, Gates stayed on and had a role in the president's inaugural committee. He also was part of a lobbying group to help push Trump's agenda, but he was forced out in April amid questions over his role in the Russia probe.
George Papadopoulos, a former foreign policy adviser to the Trump campaign, pleaded guilty in October to lying to the FBI about his interactions with Russians linked to the Kremlin.
Court documents show Papadopoulos worked to create a relationship between the campaign and the Kremlin after Trump secured the Republican nomination.
Carter Page is an American oil industry consultant who served as a foreign policy adviser to Trump during his presidential campaign.
Various U.S. intelligence agencies, including the CIA, NSA and FBI, have investigated him for alleged contact he has had with Russian officials under U.S. sanctions. He distanced himself from the Trump campaign in September 2016 while under scrutiny.
The Foreign Intelligence Surveillance Court issued a warrant to allow the Justice Department to surveil Page in the summer of 2016 based on evidence he was working as a Russian agent.
In March 2017, before news of the FISA warrant became public, Page sent a letter to the Senate intelligence committee saying he may have been wiretapped during the time he spent at Trump Tower for the campaign.
Political consultant Roger Stone was an adviser to Trump during his campaign, but exited the team in August 2015. He remained a Trump supporter and said he communicated with WikiLeaks founder Julian Assange in order to obtain information on Clinton. He also acknowledged communicating with Democratic National Committee hacker Guccifer 2.0, which U.S. intelligence agencies believe is a handle used by Russian intelligence.
He answered questions from staffers of the House intelligence committee Sept. 26, saying he was unaware WikiLeaks planned to publish Clinton's emails. He said he only knew about it beforehand "by reading about it on Twitter."
In February 2016, U.S. intelligence agencies said they were investigating whether Stone had any contact with Russian officials during the time he was involved in Trump's campaign.
During his Sept. 26 interview, he said neither he nor anyone involved in the Trump campaign colluded with Russia.
The Russian president has repeatedly denied any government involvement in meddling in the U.S. election or hacking of political figures' email accounts.
In July 2017, when he met with Trump for the first time, he again denied the accusations. During the 2016 campaign, Putin lauded Trump as a "really brilliant and talented person," and Trump called Putin a "strong leader."
The relationship between the two countries, though, has been strained over U.S. sanctions on Russia first imposed by the Obama administration and continued under Trump over alleged election meddling.
Sergey Kislyak served as the Russian ambassador to the United States from shortly before Barack Obama became president in 2008 until July 23. Meetings between Kislyak and members of Trump's campaign team have come under scrutiny.
Trump forced Flynn to resign Feb. 13 for failing to disclose the nature of a meeting he had with the ambassador before Trump's inauguration. Kislyak met twice with then-Sen. Sessions, who did not disclose the meetings during Senate confirmation hearings to become attorney general. Kushner also met with Kislyak in 2016 and did not disclose it to congressional and federal officials.
For his part, Kislyak said his interactions with Trump surrogates are part of his job as a diplomat -- to make connections with political figures in the United States.
Status of investigations
The FBI began its Russia probe in the summer of 2016 and impaneled at least one grand jury in Alexandria, Va., to investigate Flynn and payments he received from foreign interests.
On May 17, Rosenstein appointed special counsel Mueller to oversee the FBI's investigation. The team also is considering whether Trump obstructed the FBI investigation into Flynn, though a formal investigation has not been launched.
Mueller assembled a legal team that includes Andrew Weissman, who once ran the Justice Department's fraud section, Deputy Solicitor General Michael Dreeben, Jay Sekulow, Michael Bowe, John Dowd, and three partners from his former law firm, Aaron Zebley, Jeannie Rhee and James Quarles.
On Aug. 3, unnamed sources told CNN and The Wall Street Journal that Mueller had convened a grand jury and issued subpoenas for documents related to Trump Jr.'s meeting with a Russian lawyer.
The team has the legal authority to issue subpoenas and can use its own discretion whether to inform members of the Trump administration about the investigation's progress. Trump has the authority to fire Mueller, though senators have introduced at least two pieces of legislation to prevent that.
Mueller's investigation issued its first charges on Oct 30, against Manafort and a former business associate, Rick Gates.
The Senate Select Committee on Intelligence and the Senate Committee on the Judiciary are investigating Russian election meddling.
The intelligence committee heard testimony from Comey on his dismissal and interactions with Trump; has subpoenaed documents from Flynn; and has interviewed Manafort and Trump Jr.
The judiciary committee in June announced it would investigate whether the Obama and Trump administrations improperly interfered with the FBI investigation into Russia.
There are been some disagreement between the two Senate committees on witnesses, and judiciary committee Chairman Chuck Grassley said he would consider subpoenaing Comey and other witnesses.
U.S. House of Representatives
This House Permanent Select Committee on Intelligence is investigating whether the Trump campaign colluded with Russia in election meddling. On March 20, Comey told the committee there was a counterintelligence investigation into Trump. On Sept. 26, Stone said there was no collusion between the Trump campaign and the Russian state.
In April, the committee's chairman, Rep. Devin Nunes, said he would temporarily step aside from the panel's Russia investigation after he gave wiretapping evidence to Trump before he shared it with panel members.
Rep. Mike Conaway, R-Texas, took over the Russia investigation.
On July 12, Rep. Brad Sherman, D-Calif., introduced articles of impeachment against Trump, though the measure attracted virtually no support, even among Democrats. It had one co-sponsor, Rep. Al Green, D-Texas.
Democrats have sought to tamp down talk of impeaching Trump for fear it would backfire among moderates and shift focus away from the ongoing investigations.
Sherman's articles allege Trump obstructed justice by firing Comey after Comey refused to end an investigation into Flynn at Trump's behest.
Articles of impeachment are the first step on a long path set out in the Constitution for removing a president from office. Given the Republican control of both the House of Representatives and Senate, Sherman's measure has virtually no chance of advancing with the majority necessary in each chamber.