Key dates related to the investigation of the Trump campaign's alleged ties to Russia:
Paul Manafort and Rick Gates begin work as consultants for the Party of Regions, a pro-Russian political party in Ukraine led by Victor Yanukovych, the country's former prime minister. Manafort is a veteran Republican political operative who worked on the U.S. presidential campaigns of Gerald Ford, Ronald Reagan, George H.W. Bush and Bob Dole.
With the help of his Russian patrons and his American political consultants, Yanukovych is elected president of Ukraine.
Following months of violent clashes between protesters and police across Ukraine, Yanukovych flees Ukraine and enters exile in Russia. U.S. government later opens investigation into Manafort's foreign lobbying and political work.
New York real estate billionaire Donald J. Trump announces his candidacy for U.S. president as a Republican.
The FBI contacts the Democratic National Committee's IT help desk, cautioning that at least one of its computers has been compromised by Russian hackers. A technician scans the system but fails to find evidence of the intrusion.
Manafort joins Trump campaign as a volunteer consultant. George Papadopoulos is named one of five foreign policy advisers to the Trump campaign, and meets with people associated with the Russia government amid discussions to set up a meeting between Trump and Putin.
Papadopoulos meets with Russian national who he says offered "dirt" on Democratic presidential candidate Hillary Clinton, including thousands of emails. Papadopoulos emails other members of Trump campaign about Russian offer of dirt on Clinton and offer for Trump to meet with Putin. Democratic National Committee becomes aware of the scope of the months-long intrusion into its email systems by hackers U.S. intelligence agencies later linked to the Russian government.
Manafort promoted to campaign chairman and chief strategist, taking command of the Trump campaign.
Manafort attends meeting at Trump Tower in New York with Russian lawyer named Natalia Veselnitskaya, who promised to provide the Trump campaign damaging information about Clinton. Donald Trump Jr. and Jared Kushner are also in the meeting. WikiLeaks founder Julian Assange says his website will publish a batch of Clinton emails.
Trump becomes the Republican nominee for president at the party's convention in Cleveland, Ohio. In speech the following week, Trump encourages Russians to release hacked Clinton emails. FBI opens investigation into Russian government's attempt to influence the election, including whether members of Trump's campaign are involved.
The New York Times reports that Manafort's name appears on a secret list of payments made by the Yanukovych regime. Manafort resigns from Trump campaign the day after The Associated Press reports he failed to register as a foreign agent after arranging a covert lobbying campaign in the United States on behalf of the Ukrainian Party of Regions.
Donald Trump wins presidential election.
FBI Director James Comey, who was overseeing the ongoing investigation into Russian meddling in the 2016 presidential election, briefs Trump on contents of unverified dossier that contains salacious allegations about him and his campaign. Trump inaugurated as 45th President of the United States. Papadopoulos interviewed by the FBI about his contacts with Russians.
Trump fires Comey. Former FBI Director Robert Mueller is appointed as special counsel to take over the probe.
Manafort files paperwork with the Justice Department retroactively disclosing under the Foreign Agents Registration Act that his firm received more than $17 million working for the government of Ukraine between 2012 and 2014. The Washington Post reports that Mueller is investigating Trump for obstruction of justice.
FBI agents conducted a raid at former Trump campaign chairman Paul Manafort's home in Alexandria, Virginia. Papadopoulos arrested by FBI at Dulles International Airport.
Mueller impanels criminal grand jury in Washington, D.C.
Papadopoulos pleads guilty to making false statements to the FBI, as part of apparent agreement to cooperate with Mueller's investigation. Mueller files 12 count criminal indictments against Manafort and Gates.