President Donald Trump Joshua Roberts | Reuters

The Mueller report is in — but we haven't heard the whole story yet. Only a summary of special counsel Robert Mueller's highly anticipated report on Russian election interference, obstruction and possible Trump-campaign collusion has so far been released by Attorney General William Barr. But that four-page document, shared by Barr on Sunday with the leaders of the House and Senate Judiciary committees, has already been touted by President Donald Trump and his supporters as a "total and complete exoneration." Barr wrote that Mueller's final report "did not find that the Trump campaign or anyone associated with it conspired or coordinated" with Russia — a massive political victory for Trump that lends credence to his long-asserted refrain of "no collusion." Mueller also made no determination on whether Trump himself obstructed justice, according to the summary. But Barr and Deputy Attorney General Rod Rosenstein, who received Mueller's report on Friday and reviewed it over the weekend, concluded that the special counsel's evidence was "not sufficient to establish that the President committed an obstruction-of-justice offense." The Financial Times' Edward Luce said on MSNBC's "Morning Joe" that the summary's revelations made Sunday "the best day of Trump's presidency." But while Barr's summary did provide answers on some of the key questions dogging Trump since the presidential election, it leaves many more unanswered. Here are five remaining questions in the wake of Barr's letter:

How long is the report, and what will the public see?

Barr's brief letter to Sen. Lindsey Graham, R-S.C., Sen. Dianne Feinstein, D-Calif., Rep. Jerrold Nadler, D-N.Y., and Rep. Doug Collins, R-Ga., includes quotations from Mueller's report but no full sentences. It also says nothing about the length of the report or the level of detail it provides. Democrats and Republicans alike had called on Barr to publicly release the report. "The American people have a right to the truth," House Speaker Nancy Pelosi, D-Calif., and Senate Minority Leader Chuck Schumer, D-N.Y., said in a statement Friday. "The watchword is transparency." Graham, in a press conference Monday, said "my desire is for the public to get as much of the report as possible." Barr said the same in his letter — but noted that "the report contains material that is or could be subject" to federal rules imposing "restrictions on the use and disclosure" of testimony from Mueller's grand jury. For now, it remains unclear when the report will be made publicly available and how much of it may be redacted or otherwise kept confidential.

Why didn't Mueller interview Trump?

According to the summary, Mueller's team of 19 lawyers and about 40 FBI agents interviewed "approximately 500 witnesses" over the investigation's nearly two-year duration. Trump wasn't one of them. The president's lawyers had resisted letting Trump sit down for a face-to-face interview with federal investigators, saying it would be a "perjury trap" designed to manipulate him into lying. John Dowd, Trump's former lawyer, said in February that he had advised Trump against sitting for an interview, explaining that "what I was worried about is that he really couldn't do it. He couldn't do it." CNN, citing a source familiar with the matter, reported Monday that the special counsel and Justice Department officials had deliberated "at length" about subpoenaing Trump for an interview but ultimately decided against it. After a monthslong tug-of-war, the special counsel ended up submitting a written list of questions to Trump's attorneys, which were answered in late November. House Intelligence Committee Chairman Adam Schiff, D-Calif., said in an ABC News interview Sunday, "It was a mistake to rely on written responses by the president." Congressional ethics and investigations attorney Andrew Herman said it is "unsurprising" that Trump was never interviewed in the probe. "The office of the president is special, and he has special privileges," Herman told CNBC. "No one else has a memo in the Department of Justice files that says 'you can't indict this person while they're sitting in office.'"

What about the existing investigations?

Mueller's probe, launched days after Trump fired former FBI Director James Comey in May 2017, is now technically complete. But many of the cases lodged by Mueller are far from finished. Less than two weeks before filing his report, Mueller wrote in Washington, D.C., court that Rick Gates, the longtime partner of former Trump campaign chairman Paul Manafort, "continues to cooperate" in several ongoing investigations. Gates still has not been sentenced. The trial date for Roger Stone, the self-described political dirty trickster and confidant of Trump who was arrested in late January on charges of lying to Congress and witness tampering, has recently been set for Nov. 5. Stone has pleaded not guilty to the charges, which revolve around statements he made to Congress about his alleged efforts to have WikiLeaks release material hacked by Russian agents from Democrats, including Hillary Clinton's campaign chairman, during the 2016 campaign. Trump's first national security advisor, Michael Flynn, has yet to be sentenced in his cases on a charge of lying to FBI agents about his conversations with Russia's then-ambassador to the U.S., Sergey Kislyak. The still-pending cases appear to have been transferred to proximate U.S. attorneys' offices. A spokesman for the special counsel confirmed to CNBC that control of Gates' and Stone's cases had been handed over to the U.S. attorney's office in Washington. The Washington U.S. attorney's office had been part of Stone's case "from the outset," the spokesman added. That office has also been involved in the case of Concord Management and Consulting, the company accused of backing a Russian "troll farm" meant to influence the 2016 presidential election, CNN reported Saturday. The outlet also reported that plans to transfer Flynn's case, as well as the pursuit of grand jury testimony from Stone associate Andrew Miller, have not been finalized yet.

What will Democrats do?

Even before Mueller submitted the Russia report, Democrats in the House had opened a sweeping probe into Trump, his administration and dozens of his associates. That probe has three main points of focus: alleged obstruction of justice by Trump and others and the "alleged cover-up of violations of the law"; alleged corruption in areas including violations of the Constitution's emoluments clause "and other criminal misuses of official positions for personal gain"; and alleged abuses of power, such as attacking the press and misusing the presidential pardon power. It's unclear how the trajectory of that probe might be altered in light of Barr's determination that there was insufficient evidence to lodge an obstruction-of-justice offense against Trump. Nadler said early in March that he believes Trump has "very clearly" obstructed justice. On Sunday, Nadler said, "We will ask the attorney general to testify before the House Judiciary Committee. We will demand the release of the full report." Rep. Eric Swallwell, D-Calif., another member of the Judiciary Committee, said Friday on HBO's "Real Time with Bill Maher" that "we're going to subpoena" Mueller to testify, as well. In the meantime, Swallwell and other Democrats have made clear that they aren't sold on Barr's summary alone. Swallwell TWEET Until we hear from Mueller, call it the Barr Report.

What will Republicans do?