Special counsel Robert Mueller's investigation, and he has now submitted his report to Attorney General William Barr. But the extent of the probe's impact is not yet known.
Here's a guide to understanding how we got here, and what may come next.
It started May 17, 2017, eight days after President Trump fired FBI Director James Comey.
- Mueller, a former federal prosecutor and director of the FBI, was given a broad mandate: A "full and thorough investigation of the Russian government's efforts to interfere in the 2016 presidential election ... any matters that arose or may arise directly from the investigation ... any other matters" within the scope of the special counsel law.
No new indictments are expected, but 34 individuals and three separate companies have been charged. There have been seven guilty pleas and 99.5 months in prison served.
- Those charged include: Paul Manafort, former Trump campaign chairman; Michael Cohen, President Trump's former personal attorney; and Michael Flynn, who was briefly National Security Adviser.
- Twenty-five Russian nationals and three Russian companies face 161 total charges as part of Mueller's probe, though it is unlikely they will ever see an American court.
The public may never see all of Mueller's findings — that decision rests with William Barr, the attorney general.
- Justice Department guidance says Barr should only submit a "brief notification" containing "an outline of the actions and the reasons for them." He can choose to make much of Mueller's report public if he deems it in the public interest.
Regardless of what Mueller's report shows, congressional investigations are ongoing.
- House Intelligence Committee Chairman Adam Schiff, a California Democrat, has expanded the parameters of the committee's probe.
- House Judiciary Committee Chairman Jerry Nadler has launched an extensive investigation into whether Mr. Trump obstructed justice by firing Comey. In early March, the Judiciary Committee from 81 entities and individuals, from the White House to Donald Trump Jr. and Trump Organization CFO Allen Weisselberg.
The U.S. Attorney's office in the Southern District of New York has also launched investigations into Mr. Trump and the Trump organization.
- Former U.S. Attorney Preet Bharara, who was fired by Mr. Trump in 2017, this week that unlike Mueller, the Southern District is not blocked from any wider investigations by Justice Department guidelines. "They can look at crime as they see fit, "Bharara said. "They can bring a case against anyone they think that justice needs to be served. They don't care how powerful you are, they don't care what party you're from, they don't care what your assets are. They're tough and aggressive and independent."
- The New York state attorney general has into Mr. Trump's business dealings.