The mounting inquiries are building into a cascade of legal challenges that threaten to dominate Trump's third year in the White House. In a few weeks, Democrats will take over in the House and pursue their own investigations into all of the above - and more.
The ultimate consequences for Trump are still unclear. Past Justice Department opinions have held that a sitting president may not be charged with a federal crime.
House Democrats may eventually seek to impeach Trump. But, for now, removing him from office appears unlikely: It would require the support of two-thirds of the Senate, which is controlled by Republicans.
However, there has been one immediate impact on a president accustomed to dictating the country's news cycles but who now struggles to keep up with them: Trump has been forced to spend his political capital - and that of his party - on his defense.
On Capitol Hill this week, weary Senate Republicans scrambled away from reporters to avoid questions about Trump and his longtime fixer Michael Cohen - and Cohen's courtroom assertion that he had been covering up Trump's "dirty deeds" when he paid off two women who claimed they had affairs with the president before he was elected.
"I don't do any interviews on anything to do with Trump and that sort of thing, OK?" said Sen. James Risch, R-Idaho.
"There's no question that it's a distraction from the things that obviously we would like to see him spending his time on, and things we'd like to be spending our time on," said Sen. John Thune, R-S.D. "So that's why I'm hoping that some of this stuff will wrap up soon and we'll get answers, and we can draw conclusions, and we can move on from there."
Sen. Richard Blumenthal, D-Conn., summed it up another way: "It's been a bad week for Individual Number One," referring to the legal code name prosecutors in Manhattan used in court filings to refer to the president.
Trump attorney Rudy Giuliani did not respond to a request for comment. Neither did White House or Trump Organization officials.
As the bad news has rolled in, the president has cut back his public schedule. He spent more time than usual in his official residence this week, with more than two dozen hours of unstructured "executive time," said a person familiar with his schedule.
In several tweets on Thursday, Trump sought to cast doubt on two former advisers who have cooperated with investigators. Cohen, Trump said, just wanted a reduced prison sentence. Former national security adviser Michael Flynn, he said, was the victim of scare tactics by the FBI.
Then - after wordy explanations of how both men had gone wrong - Trump tried to sum up his increasingly complex problems with a simple explanation.
"WITCH HUNT!" he wrote.
"He's just never been targeted by an investigation like this," said Timothy O'Brien, a reporter who wrote a biography of Trump, adding that the longtime real estate mogul had contended with extensive litigation in his business career, but never legal threats of this scale. "The kind of legal scrutiny they're getting right now - and the potential consequences of that scrutiny - are unlike anything Donald Trump or his children have ever faced."
THE SPECIAL COUNSEL PROBE
Mueller's investigation began in May 2017 after Trump fired FBI Director James Comey. The special counsel's mandate: to investigate Russian interference in the 2016 campaign and whether the Kremlin worked with Trump associates. Mueller is also examining whether the president has sought to obstruct the Russia probe.
So far, Mueller has charged 33 people. That includes 26 Russian nationals - some of whom allegedly stole emails and other data from U.S. political parties, others of whom allegedly sought to influence public opinion via phony social media postings.
Several Trump aides have also pleaded guilty.
Paul Manafort, Trump's former campaign chairman, was found guilty in August of tax and bank fraud charges and pleaded guilty in September to conspiracy and obstruction charges unrelated to his work for the campaign. He agreed to cooperate with Mueller's investigation - though the special counsel's office recently asserted he has been lying to investigators.
Flynn, Trump's former national security adviser, admitted to lying to the FBI about his conversations with the Russian ambassador. Rick Gates, Trump's former deputy campaign chairman, admitted to conspiracy and lying to the FBI. Former foreign policy adviser George Papadopoulos pleaded guilty to lying to the FBI about his Russian contacts. Cohen admitted to lying about efforts to build a Trump project in Moscow that lasted into Trump's presidential run. All agreed to cooperate with investigators.
It's unclear where Mueller's inquiry is headed - and whether it will end with a spate of indictments reaching further into Trump's world or with a written report submitted to the Justice Department.
Trump has repeatedly denied there was any "collusion" between his associates and Russia and has attacked the investigation as a fishing expedition led by politically biased prosecutors. Advisers said he has recently ramped up his attacks - hoping to undermine confidence in Mueller's work - because he believes the probe is at a critical stage.
THE CAMPAIGN-FINANCE INVESTIGATION
Separately, federal prosecutors in Manhattan have pursued another investigation that emerged out of the 2016 campaign: hush-money payments Cohen made to two women who said they'd had extramarital affairs with Trump.
Cohen, who was sentenced Wednesday to three years in prison for what a judge called a "veritable smorgasbord of criminal conduct," pleaded guilty to campaign-finance violations in connection to the payments.
Cohen also named who told him to pay off the women: Trump.
"He was very concerned about how this would affect the election," Cohen told ABC News in an interview that aired Friday.
Trump has denied he directed Cohen to break the law by buying the silence of former Playboy playmate Karen McDougal and adult-film star Stormy Daniels. He also said Cohen, as his lawyer, bore responsibility for any campaign finance violations.
"I never directed him to do anything wrong," Trump told Fox News on Thursday. "Whatever he did, he did on his own."
Prosecutors also revealed Wednesday they had struck a non-prosecution agreement with AMI, the company that produces the National Enquirer tabloid, for its role in the scheme.
The company admitted it had helped pay off one of Trump's accusers during the campaign. It said it had done so in "cooperation, consultation, and concert with" one or more members of Trump's campaign, according to court filings.
It is unclear whether prosecutors will pursue charges against campaign or Trump Organization officials as part of the case.
But at the White House, advisers have fretted that this case - and not Mueller's - could be the biggest threat to Trump's presidency. House Democrats have already indicated the campaign-finance allegations could be potential fodder for impeachment proceedings.
SCRUTINY OF THE INAUGURAL COMMITTEE
The nearly $107 million donated to Trump's inaugural committee has drawn the attention of Mueller, who has probed whether illegal foreign contributions went to help put on the festivities.
The special counsel already referred one such case to federal prosecutors in Washington. In late August, an American political consultant, W. Samuel Patten, admitted steering $50,000 from a Ukrainian politician to the inaugural committee through a straw donor.
Patten pleaded guilty to failing to register as a foreign lobbyist and agreed to cooperate with prosecutors.
On Friday, Rep. Adam Schiff, D-Calif., the incoming chairman of the House Intelligence Committee, said his panel plans to investigate possible "illicit foreign funding or involvement in the inauguration."
The Wall Street Journal reported this week that federal prosecutors in New York are examining whether the inaugural committee misspent funds. The Washington Post has not independently confirmed that report.
Officials with the committee, which was chaired by Trump's friend Tom Barrack, said they were in full compliance "with all applicable laws and disclosure obligations" and have not received any records requests from prosecutors.
White House spokesman Hogan Gidley told reporters this week that questions about the committee's practices have "nothing to do with the president of the United States."
THE EMOLUMENTS LAWSUITS
Trump also faces a pair of civil lawsuits alleging he has violated the Constitution by doing business with foreign and state governments while in office.
Trump still owns his private company, though he says he's given up day-to-day control to his sons Donald Trump Jr. and Eric Trump. Since the 2016 election, Trump's businesses have hosted parties for foreign embassies, hosted Malaysia's prime minister and Maine's governor, and rented more than 500 rooms to lobbyists paid by the Saudi government.
The lawsuits allege that such transactions violate a Constitutional ban on presidents taking emoluments, or payments, from foreign or state governments. One complaint was filed by congressional Democrats; the other by the Democratic attorneys general of Maryland and the District of Columbia.
"What we want to do is be able to tie the flow of money from foreign and domestic sovereigns into Donald Trump's pocketbook," said Karl Racine, D, the D.C. attorney general. He called the emoluments clauses "our country's first corruption law."
The plaintiffs are seeking to have Trump barred from doing business with governments. But the more immediate threat for Trump and his company is the legal discovery process, in which the plaintiffs are seeking documents detailing his foreign customers, how much they paid - and how much wound up in the president's pocket.
So far, Trump - who is represented by the Justice Department and a private attorney - has failed to get the cases dismissed or block discovery.
Earlier this month, the two attorneys general sent Trump's company a raft of subpoenas. They expect to get answers early next year.
NEW YORK STATE INQUIRIES
In New York, where Trump's business is based, incoming Attorney General Letitia James, D, is preparing to launch several investigations into aspects of his company.
"We will use every area of the law to investigate President Trump and his business transactions and that of his family as well," James told NBC News.
She said she wanted to look into whether Trump had violated the emoluments clause by doing business with foreign governments in New York and examine allegations detailed by the New York Times that Trump's company engaged in questionable tax practices for decades.
New York state's tax agency has also said it is considering an investigation into the company's tax practices.
Earlier this year, New York Attorney General Barbara Underwood filed suit against Trump and his three eldest children, alleging "persistently illegal conduct" at the Donald J. Trump Foundation, a case spurred by reporting by The Post in 2016.
Trump is accused of violating several state charity laws, including using his charity's money to pay off legal settlements for his for-profit businesses. He used the foundation to buy a portrait of himself that was hung up at one of his resorts. Trump also allegedly allowed his presidential campaign to dictate the charity's giving in 2016 - despite laws that bar charities from participating in campaigns.
The attorney general has asked for Trump to pay at least $2.8 million in penalties and restitution and that he be barred from running a charity in New York for 10 years.
Trump has called the suit politically motivated and "ridiculous."
Last month, a New York state judge denied a request by Trump's attorneys to throw out the suit.
Meanwhile, a defamation suit against Trump by former "Apprentice" contestant Summer Zervos has also quietly advanced through the New York courts.
A judge has allowed Zervos to seek discovery - including possibly deposing the president - as the two sides wait for a panel of New York appellate judges to rule on Trump's latest move to block the lawsuit.
Trump has argued that, as a sitting president, he is immune from the claims in both the foundation and Zervos case. He maintains that the 1997 Supreme Court decision in Clinton v. Jones - which said that presidents do not have immunity from civil litigation - does not apply in state courts.
