Key moments included Mueller saying his report did not exonerate the president as Trump has claimed and contending he could be charged after leaving office.
But he also did not answer many questions, frustrating both Republicans, who tried to discredit his probe, and Democrats who pressed him on whether he had left it to Congress whether to pursue impeachment, believing that Justice Department policy prevented him from indicting a sitting president.
Democrats on the House Judiciary and Intelligence committees labored for months to bring the 74-year-old Mueller before Congress to answer lingering questions about his 22-month investigation.
Mueller was reluctant to appear before Congress, and only agreed to appear under subpoena from both panels. "The report is my testimony," he said in his only public statement on the report in May.
Here is how the day developed:
3:25 p.m. 'Had it been anyone else in the country they would have been indicted,' Chairman Schiff said as hearing ended
After more than six hours of facing questions, Robert Mueller spent his last few minutes of his historic testimony listening to bluntly-worded final comments from Rep. Adam Schiff,
"The facts you set out in your report and have spoken about today, tell a disturbing tale of a massive Russian interference in our election, of a campaign so eager to win, so driven by greed, it was willing to accept the help of a hostile power in a presidential election decided by a handful of votes in a few key states," Schiff said.
"They risked going to jail by lying to you, to the FBI and to congress about it and indeed some have gone to jail over such lies. And your work speaks of a president who committed many acts of obstruction of justice. Had it been anyone else in the country they would have been indicted," Schiff said.
Schiff then excused Mueller and the former special counsel left the room quietly without making further comment.
3:14 p.m. Mueller is asked about Trump's tax returns
"Your office did not obtain the president's tax returns which could otherwise show foreign financial services, correct?" Rep. Raja Krishnamoorthi, an Illinois Democrat, asked.
"I'm not going to speak to that," Mueller said.
"In July 2017, the president said his personal finances were off limits or outside the per view of your investigation. And he drew a red line around his personal finances.Were the president's personal finances outside the purview of your investigation?" Krishnamoorthi asked.
"I'm not going to get into that," Mueller responded.
"Were you instructed by anyone not to investigate the president's personal finances?" Krishnamoorthi said.
"No," Mueller answered.
3:13 pm Mueller said Trump's written answers were 'generally' not truthful
"Director Mueller, is it fair to say the president's written answers were not only inadequate and incomplete, because he didn't answer many of your questions, but where he did, his answers showed he wasn't always being truthful?," Rep. Val Demings, D-Fla., asked.
"I would say generally," Mueller said.
3:03 p.m. Mueller questioned on why he didn't subpoena Trump
A Democrat posed a question that many in his party have asked from early in Mueller's investigation.
"Why didn't you subpoena the president?" Rep. Sean Maloney, D-N.Y., asked.
"At the outset, after we took over the investigation and began and pursued it, one of the things we anticipated wanting to accomplish is getting the -- having the interview of the president," Mueller said. "We negotiated with him for a little over a year, and I think what you alluded to in the appendix lays out our expectations as a result of those negotiations. But when we were almost toward the end of our investigation, we had no success to get the interview of the president, we decided we did not want to exercise the subpoena power because of the necessity of ending the investigations," Mueller said.
"Excuse me?" Maloney said.
"If we did subpoena the president, he would fight the subpoena, and we would be under the investigation for a substantial period of time," Mueller said
2:47 p.m. Mueller said Russians are actively trying to interfere in U.S. elections
"In your investigation, did you think that this was a single attempt by the Russians to get involved in our election? Or did you find evidence to suggest they'll try to do this again?" Rep. Will Hurd, R-Texas, asked.
"It wasn't a single attempt. They're doing it as we sit here. And they expect to do it during the next campaign," Mueller said.
2:30 pm Mueller refuses to answer questions about Donald Trump Jr.
After the hearing resumed, Mueller was asked about another matter that critics have questioned: his handling of the president's son.
"Did you want to interview Donald Trump Jr.?" Rep. Eric Swalwell, D-Calif., asked.
"I'm not going to discuss that," Mueller said.
"Did you subpoena Donald Trump Jr.?" Swalwell asked.
"I'm not going to discuss that," Mueller answered.
2:15 p.m. Chairman Schiff calls a recess for 5-10 minutes after Mueller questioned about Trump and WikiLeaks
The plan was that Mueller would testify for about two hours before the House Intelligence Committee but aides said it could go somewhat longer.
A few minutes earlier Rep. Mike Quigley, an Illinois Democrat, ran through a series of slides showing Trump quotes about WikiLeaks, prompting Mueller to call Trump's encouraging comments "problematic."
"If we could put up slide 6: 'This just came out. Wikileaks. I love WikiLeaks.' Donald Trump, October 10, 2016. 'This WikiLeaks stuff is unbelievable. You have to read it.' October 12, 2016. 'This WikiLeaks is like a treasure trove.' Donald Trump October 31, 2016. 'Boy, I love reading those WikiLeaks.' Would any of those quotes disturb you, Mr. Director?" Quigley asked.
"How do you react to those? " Quigely asked
"It's problematic is an understatement to say the least - in terms of what it displays in terms of giving some hope or some boost to what is and should be illegal activity," Mueller answered.
"Donald Trump Jr. had direct communications with WikiLeaks during the campaign period. On October 3, 2016. WikiLeaks penned another message to Trump Jr. asking: "You guys to have a link to Clinton. Julian Assange responded to that, he had already done so. This behavior at the very least disturbing?
"Disturbing and also subject to investigation," Mueller said.
"Could it be described as aide and comfort to a hostile service, sir?? Quigley pressed.
"I wouldn't characterize it with any specificity," Mueller said.
1:41 p.m. Republican lawmaker presses Mueller on whether attorney general has authority to exonerate Trump
Rep. Mike Turner, R-Ohio, returned to Republicans' theme of questioning Mueller's decision not to exonerate Trump, something that has frustrated the president and his allies.
With a screenshot of a CNN chyron from earlier Wednesday reading "Mueller: Trump was not exonerated," Turner pressed Mueller on the issue.
"If your report is to the attorney general and the attorney general doesn't have the power to exonerate and he does not -- he knows that you do not have that power, you don't have to tell him that you're not exonerating the president. He knows this already. So then that kind of changes the context of the report," he said. "The attorney general has the power to exonerate? He has not been given that authority."
"No," Mueller replied. "We included in the report for exactly that reason."
"You have no more power to declare him exonerated than you have the power to declare him Anderson Cooper," Turner said. "The statement about exoneration is misleading and meaningless and colors this investigation. One word out of the entire portion of your report and it's a meaningless word that has no legal meaning and it has colored your entire report."
"Mr. Mueller, would you agree with me that the attorney general does not have the power to exonerate?" Turner continued.
"I'm going to pass on that," Mueller said.
"Why?" Turner pressed.
"Because it embroils us in a legal discussion. I'm not prepared to deal with a legal discussion in that arena," Mueller answered.
1:14 p.m. Mueller said his investigation was not a witch hunt and that Russian interference is not a hoax, as Trump has claimed
"Your investigation is not a witch hunt, is it?" Rep. Adam Schiff, D-Calif., asked.
"It is not a witch hunt," Mueller said.
"When the president said the Russian interference was a hoax, that was false, wasn't it," Schiff asked.
"True," Mueller answered.
"It's also clear from your report that during that Russian outreach to the Trump campaign, no one associated with the Trump campaign ever called the FBI to report it, am I right?" Schiff asked.
"I don't know that for sure," Mueller said.
"In fact, the campaign welcomed the Russian help, did they not?" Schiff asked.
"I think we report, in the report, say indications that that occurred, yes," Mueller answered.
"The president's son said when he was approached about dirt on Hillary Clinton, that the Trump campaign would love it," Schiff said.
"That's generally what was said, yes," Mueller said.
"The president himself called on the Russians to hack Hillary's emails?," Schiff said.
"There's a statement by the president in those general lines," Mueller responded.
"Numerous times during the campaign, the president praised the releases of the Russian-hacked emails through Wikileaks?" Schiff asked.
"That did occur," Mueller said.
1:09 p.m. Mueller corrects earlier statement to Democratic lawmaker at first hearing
"Now, before we go to questions, I want to go back to one thing that was said this morning by Mr. Lieu who said, and I quote, 'You didn't charge the president because of the OLC opinion'," Mueller said, referring to the Justice Department Office of Legal Counsel opinion that it was against department policy to indict a sitting president. "That is not the correct way to say it. As we say in the report, and as I said at the opening, we did not reach a determination as to whether the president committed a crime," Mueller explained.
1 p.m. Top Republican gives opening remarks
"Welcome, everyone, to the last gasp of the Russia collusion conspiracy theory," Rep. Devin Nunes, R-Calif., said as he began his opening statement.
"Among congressional Democrats, the Russia investigation was never about finding the truth," he said as he finished. "It’s always been a simple media operation, and by their own accounts, that operation continues in this room today. Once again, numerous pressing issues this Committee needs to address are put on hold to indulge the political fantasies of people who believed it was their destiny to serve in the Hillary Clinton administration. It’s time for the curtain to close on the Russia hoax—the conspiracy theory is dead. At some point, I would argue, we’re going to have to get back to work," Nunes said.
12:52 p.m. Second hearing begins before House Intelligence Committee
Rep. Adam Schiff, the California Democrat who chairs the House Intelligence Committee, gaveled in another two hours of questioning of Robert Mueller.
"Your report, for those who have taken the time to study it, is methodical and it is devastating, for it tells the story of a foreign adversary’s sweeping and systematic intervention in a close U.S. presidential election," he said in an opening statement.
"That should be enough to deserve the attention of every American, as you well point out. But your report tells another story as well. For the story of the 2016 presidential election is also a story about disloyalty to country, about greed, and about lies," he continued.
"Your investigation determined that the Trump campaign – including Trump himself – knew that a foreign power was intervening in our election and welcomed it, built Russian meddling into their strategy, and used it.
"Disloyalty to country. Those are strong words, but how else are we to describe a presidential campaign which did not inform the authorities of a foreign offer of dirt on their opponent, which did not publicly shun it, or turn it away, but which instead invited it, encouraged it, and made full use of it?" he said.
12:10 p.m. First hearing ends
Mueller finished his testimony before the House Judiciary Committee after more than three hours of questioning. After a break, Mueller would be testifying before members of the House Intelligence Committee about the section of his report dealing with whether there was collusion between the Trump campaign and the Russian government or individuals tied to that government.
12:07 p.m. Mueller declines to comment on impeachment question
"Director Mueller, at your May 29, 2019, press conference, you explained that, quote, 'The opinion says that the Constitution requires a process other than the criminal justice system to formally accuse a sitting president of wrongdoing,' end quote. That process, other than the criminal justice system for accusing a president of wrongdoing, is that impeachment?", Rep. Veronica Escobar, D-Texas, asked.
She was the last Democrat to ask a question.
"I'm not going to comment on that," Mueller answered.
"In your report, you also wrote that you did not want to, quote, 'potentially preempt constitutional processes for addressing presidential misconduct,' end quote. For the non-lawyers in the room, what did you mean by, quote, 'potentially preempt constitutional processes'?"
"I'm not going to try to explain that," Mueller responded.
"That actually is coming from page 1 of Volume II. In the footnote is the reference to this. What are those constitutional processes?" she pressed.
"I think I heard you mention at least one," Mueller answered.
12:01 p.m. Democratic lawmaker questions Barr's summary of the Mueller report
"Could Attorney General Barr have avoided public confusion if he had released your summaries and executive introduction and summaries," Rep. Madeleine Dean, D-Penn., asked, referring to Barr's letter stating, in his view, the "principal conclusions" of Mueller's report, several weeks before the redacted report was released.
"I don't feel comfortable speculating on that," Mueller said, although he did send a letter to Barr stating his concerns that his report had been mischaracterized.
11:53 a.m. Republicans end their questioning on impeachment issue
A key question since his report was issued has been whether Mueller, because he believed he could not indict a sitting president, intended for Congress to deal with the issue through possible impeachment, according to the Constitution.
"One last important question. Your report does not recommend impeachment. Does it?" Rep. Mike Johnson, R-La., asked.
"I'm not going to talk about recommendations," Mueller said.
"It does not conclude that impeachment would be appropriate here, right," Johnson added.
"I'm not going to talk about that issue," Mueller answered.
11:43 a.m. Mueller emphatically defends his prosecution team against claims of political bias
"You must be aware by now that six of your lawyers donated $12,000 directly to Hillary Clinton. I'm not even talking about the $49,000 they donated to other Democrats. Just the donations to the opponent who was the target of your investigation," Rep. Kelly Armstrong, R-N.D., said.
"We strove to hire those individuals that could do the job. I've been in this business for almost 25 years, and in those 25 years, I have not had occasion once to ask somebody about their political affiliation. It is not done. What I care about is the capability of the individual to do the job and do the job quickly and seriously and with integrity," Mueller said.
11:32 a.m. Mueller denies he applied for job as FBI director
"A day before being named special counsel, did you indeed interview for the FBI director job one day before you were appointed special counsel?," Rep. Greg Steube, R-Fla., asked, repeating a claim President Trump has made multiple times as evidence Mueller was "conflicted" and biased, allegedly because Trump rejected him.
"My understanding - it was not applying for the job. I was asked to give my input on what it would take to do the job, which triggered the interview you're talking about," Mueller answered.
"So you don't recall on May 16, 2017, that you interviewed with the president regarding the FBI director job," Steube said, reminding Mueller that he was under oath.
"I interviewed with the president," Mueller said.
"Was it about the FBI director job?" Steube added.
"It was about the job, not me applying for the job," Mueller said.
"So, did you tell the vice president that the FBI director position would be the one job that you would come back for?" Steube asked.
"I don't recall that one," Mueller answered.
11:17 a.m. Mueller pushes back on how GOP lawmaker characterizes his report
"Well, what you did is you compiled a nearly 450 pages of the very worst information you gathered against the target of your investigation, who happens to be the president of the United States. And you did this knowing that you were not going to recommend charges and that the report would be made public," Rep. Guy Reschenthaler, R-Penn., said.
"Not true," Mueller responded.
10:58 a.m. Mueller defends his report
"The fundamental problem is, as I said, we've got to take your word, that your team, faithfully, accurately, impartially, and completely described all of the underlying evidence in the Mueller report, and we're finding more and more instances where this just isn't the case. And it's starting to look like, you know, having desperately tried and failed to make a legal case against the president, you made a political case instead.You put it in a paper sack, lit it on fire, dropped it on our porch, rang the doorbell, and ran," Rep. Tom McClintock, R-Calif., said.
"I don't think you’ve reviewed a report that is as thorough, as fair, as consistent as the report that we have in front of us," Mueller responded.
10:52 a.m. Mueller explains why he did not indict Trump
"And I'd like to ask you the reason, again, that you did not indict Donald Trump is because of OLC opinion stating that you cannot indict a sitting president, correct," Rep. Ted Lieu, D-Calif., asked, referring to a Justice Department Office of Legal Counsel opinion that it was DOJ policy that a sitting president cannot be indicted.
"That is correct," Mueller said.
10:37 a.m. Mueller said prosecutors can bring a charge of obstruction after a president leaves office
In an especially significant moment, the former special counsel answered one of the key outstanding questions about his report during questioning by a Republican.
"Could you charge the president with a crime after he left office?" Rep. Ken Buck, R-Colo., asked.
"Yes," Mueller said.
"You believe that he committed -- you could charge the president of the United States with obstruction of justice after he left office?" Buck asked again.
"Yes," Mueller answered.
10:23 a.m. Republican challenges Mueller on credibility of Christopher Steele
"I'm quoting from the Steele dossier, extensive evidence of conspiracy between the Trump campaign team and the Kremlin. So here's my question: Did Russians really tell that to Christopher Steele or did he just make it all up and was he lying to the FBI," Rep. Matt Gaetz, R-Fla., asked.
"Let me back up a second if I could and say as I have said earlier with regard to the Steele -- that's beyond my purview," Mueller said.
10:06 a.m. The committee takes a short break
So far, there have been 21 instances of Mueller saying "refer to the report," "I'll leave that to our report," "I direct you to the report," "I'll leave the answer to the report," "rely on the language of the report" -- answers along the lines of his previous statement that his report would be his "testimony" and that he would not go beyond it.
9:47 a.m. Democrat asks about Trump's intention in wanting to fire Mueller
"Director Mueller, you found evidence as you lay out in your report that the president wanted to fire you because you were investigating him for obstruction of justice, isn't that correct," Rep. Ted Deutch, D-Fla., said.
"That's what it says in the report. And yes, I stand by the report," Mueller said.
Deutch then pivoted to ask Mueller about his report's finding that Trump ordered then-White House counsel Don McGhan to have then-Attorney General Jeff Sessions fire Mueller.
"You found White House counsel McGahn to be a credible witness, isn't that correct?" Deutch said.
"Correct," Muller said.
"Director Mueller, the most important question I have for you today is why Director Mueller, why did the president of the United States want you fired?" Deutch asked.
"I can't answer that question," Muller answered.
9:39 a.m. Republican lawmaker asks Mueller about Peter Strzok controversy
"Peter Strzok hated Trump. You didn't know that before he was made part of your team, is that what you're saying," Rep. Louie Gohmert, R-Texas, asked about the former FBI agent who exchanged derogatory texts with former FBI lawyer Lisa Page, with whom he was having an affair.
House Republicans and President Trump have repeatedly cited Strzok as evidence that Mueller's investigation was biased from the start.
"I did not know that. And when I did find out, I acted swiftly to have him reassigned," Mueller answered.
9:08 a.m. Republican argues Mueller didn't give Trump presumption of innocence
Rep. John Ratcliffe, R-Texas, a former U.S. attorney, has a pointed back-and-forth with Mueller.
He "respectfully" criticized Mueller's comments about not exonerating Trump in the report.
"Respectfully, respectfully, it was not the special counsel's job to conclusively determine President Trump's innocence," he said, "because there is a presumption of innocence, prosecutors never, ever, need to determine it."
"Nowhere in here did it say write a report about decisions that weren't reached," Ratcliffe said.
"Americans need to know this as they listen to the Democrats and socialists on the other side of this aisle ... volume II was not authorized to be written under this law."
"Donald Trump is not above the law, but he damn sure shouldn't be below the law."
9 a.m. Top Republican presses Mueller on collusion
"Collusion is not a specific offense or a term of art in federal criminal law. Conspiracy is. In the colloquial context, collusion and conspiracy are essentially synonymous terms, correct?" Rep. Doug Collins, R-Ga., asked.
"No," Mueller said.
"On page 180, Volume 1 of your report, it said collusion is largely synonymous with conspiracy as that crime is set forth. Now, you said you chose your words carefully. Are you contradicting your report right now?" Collins asked.
"Not when I read it," Mueller answered.
"So, you would change your answer to yes, then?" Collins asked.
"No," Mueller said.
"I'm reading your report, sir. Is it a yes or no answer. Page 180, Volume 1. This is from your report," Collins added.
"Correct. And I leave it with the report," Mueller said.
8:52 a.m. Chairman Nadler asks the first question
"Director Mueller, the president has repeatedly claimed that your report found there was no obstruction and that it, completely and totally exonerated him. But that is not what your report said, is it?" Rep. Jerry Nadler, D-N.Y., asked.
"Right, that is not what the report said," Mueller said.
Nadler then asks if the report totally exonerates Trump of obstruction of justice as the president has claimed.
"So. the report did not conclude that he did not commit obstruction of justice? Is that correct," Nadler said.
"That is correct," Mueller answered.
"And what about total exoneration? Did you actually totally exonerate the president," Nadler asked.
"No," Mueller said.
8:42 a.m. Mueller is sworn in
"It is unusual for a prosecutor to testify on a criminal investigation. And given my role as a prosecutor there are reasons why my testimony will necessarily be limited," Mueller said in his opening statement.
"I also will not comment on the actions of the Attorney General or of Congress. I was appointed as a prosecutor, and I intend to adhere to that role and to the Department’s standards that govern it," Mueller added.
8:36 a.m. Judiciary Chairman Nadler gives opening statement
"Director Mueller, we have a responsibility to address the evidence that you have uncovered. You recognize as much when you said, 'The Constitution requires a process other than the criminal justice system to formally accuse a sitting president of wrongdoing.' That process begins with the work of this committee," Rep. Jerry Nadler, D-N.Y., said.
"This hearing is long overdue. We’ve had the truth for months — no American conspired to throw our elections. What we need today is to let that truth bring us confidence and closure," Rep. Doug Collins, the top Republican on the committee, said in his opening statement.
8:33 a.m. Mueller takes the witness chair
In a packed hearing room, Mueller takes a seat in the witness chair. A top aide, Aaron Zebley, takes a seat just behind him.
Shortly after Mueller sat down, a protester shouted: “Kushner and Manafort downloaded encrypted apps the day of the Trump Tower meeting” before getting pulled out of the room by Capitol Police.
7:53 a.m. Mueller arrives on Capitol Hill
Mueller arrived amid a crush of reporters and cameras for his congressional testimony in front of the House Judiciary Committee but made no comment.
Mueller testifies first before the Judiciary Committee for three hours, before fielding questions from the House Intelligence Committee for two hours. The first hearing will focus on Volume II of the Mueller report, which detailed ten instances of possible obstruction of justice by President Trump. The second hearing will center on Volume I of the report, which focused on Russian efforts to interfere in the 2016 White House race.
Lawmakers have spent weeks preparing for the hearings, and continued to prepare for the back-to-back rounds of questioning well into Tuesday evening, fielding a last-minute request from Mueller that Aaron Zebley, his longtime chief of staff, be sworn in to appear alongside him in front of the committees. A committee spokesman said Zebley would appear with Mueller on Wednesday as his counsel.
Democrats and Republicans on the House Judiciary Committee have each held mock hearings, with committee staffers playing the role of Mueller. The former special counsel has prepared with a cadre of longtime aides at the WilmerHale law firm, where he worked before accepting the special counsel appointment.
Trump has attacked Mueller ahead of the hearing, and said he may "see a little bit of it" on television.
On Monday, the Justice Department attempted to limit elements of Mueller’s testimony, saying in a letter to the former special counsel that he "must remain within the boundaries" of the public report on his investigation.