Mueller, answering questions publicly for the first time on his inquiry, also defended the integrity of his investigation as he appeared for eagerly anticipated testimony at the first of two back-to-back televised congressional hearings that carry high stakes for Trump and Democrats who are split between impeaching him or moving on to the 2020 election.
The former FBI director, who spent 22 months investigating what he concluded was Russian interference in a "sweeping and systematic fashion" in the 2016 U.S. election to help Trump and the president's conduct, appeared for more than 3-1/2 hours before the House of Representatives Judiciary Committee.
Mueller was set to testify later in the day before the House Intelligence Committee. Democrats control the House, while Trump's fellow Republicans control the Senate.
The Judiciary Committee's Democratic chairman, Jerrold Nadler, praised Mueller and said no one, including Trump, is "above the law." But Trump's Republican allies on the committee tried to paint Mueller's investigation as unfair to the president, with Louie Gohmert heatedly telling him "you perpetuated injustice" and conservative congressman Guy Reschenthaler calling the manner in which the inquiry was conducted "un-American."
Mueller's 448-page report, released in redacted form on April 18, did not reach a conclusion on whether Trump committed the crime of obstruction of justice in a series of actions aimed at impeding the inquiry, but did not exonerate him.
Democratic Representative Ted Lieu asked Mueller if the reason he did not bring a criminal indictment against Trump was the Justice Department's longstanding policy crafted by its Office of Legal Counsel against bringing criminal charges against a sitting president.
"That is correct," Mueller said.
Trump has claimed that the Mueller inquiry resulted in the president's "complete and total exoneration."
"Did you actually totally exonerate the president?" Nadler asked Mueller.
"No," Mueller replied.
Mueller's then-spokesman Peter Carr and Justice Department spokeswoman Kerri Kupec issued a joint statement on May 29 saying that Attorney General William Barr had previously stated that Mueller "repeatedly affirmed that he was not saying that, but for the OLC (Justice Department Office of Legal Counsel) opinion, he would have found the President obstructed justice."
Asked at the hearing whether he stood by that May 29 statement, Mueller said, "I would have to look at it more closely."
Mueller, accused by Trump of heading a "witch hunt" and trying to orchestrate a "coup" against the Republican president, said his inquiry was conducted in "a fair and independent manner" and that members of the special counsel's team "were of the highest integrity."
Trump has accused Mueller of having conflicts of interest, including saying Mueller wanted the president to appoint him as FBI director after firing James Comey. Mueller disputed Trump's account, saying he had not sought the FBI job from Trump. Mueller noted that Justice Department ethics officials confirmed he had no such conflicts.
"Let me say one more thing," Mueller said. "Over the course of my career, I have seen a number of challenges to our democracy. The Russian government's effort to interfere with our election is among the most serious."
The interrogation of Mueller, a reluctant witness who appeared only after being subpoenaed, afforded an opportunity for Americans, who may not have pored over the lengthy and sometimes dense report, to hear his conclusions in a highly charged hearing scheduled by Democrats, with Trump running for re-election in 2020.
'A little fast'
Mueller, 74, was surrounded by news photographers as he took his place in the packed hearing room, showing little apparent emotion as he scanned the scene. Mueller faced a series of rapid-fire questions from lawmakers in both parties, several times asking them to repeat their questions and often referring them to the text of the report itself. Some Republicans interrupted Mueller as he was trying to answer questions.
"That went a little fast for me," Mueller told Doug Collins, the committee's top Republican, at one point.
Mueller avoided being drawn into arguments with Republicans who hammered away at his inquiry, often frustrating lawmakers with responses such as "I am not going to get into that."
"And if I can finish," Mueller told Republican Matt Gaetz after the congressman interrupted him.
In a comment sure to disappoint Republicans, Mueller said he would not answer questions about the origins of the Russia probe in the FBI before he was named to take over the inquiry in 2017 or about a controversial dossier compiled by a former British intelligence agent. Republicans have tried to portray the investigation as a politically motivated attack on Trump cooked up by Democrats and various enemies.
Democrats entered the hearings hoping his testimony would rally public support behind their own ongoing investigations of the president and his administration. Democrats are deeply divided over whether to launch the impeachment process set out in the U.S. Constitution for removing a president from office for "high crimes and misdemeanors."
Mueller's inquiry detailed numerous contacts between Trump's 2016 presidential campaign and Russia at a time when the Kremlin was interfering in the 2016 U.S. election with a scheme of hacking and propaganda to sow discord among Americans and boost Trump's candidacy.
Mueller's investigative report said the inquiry found insufficient evidence to establish that Trump and his campaign engaged in a criminal conspiracy with Russia.
Democrats focused on five actions by Trump that Mueller had investigated as potential obstruction of justice, including at one point telling his White House counsel to remove the special counsel.
"Obstruction of justice strikes at the core of the government's efforts to find the truth and to hold wrongdoers accountable," Mueller testified.
Under questioning by Nadler, Mueller acknowledged that the report detailed "multiple acts by the president that were capable of exerting undue influence over law enforcement investigations, including the Russian interference and obstruction investigations."
"Well, the finding indicates ... that the president was not exculpated for the acts that he allegedly committed," Mueller told Nadler.
Attorney General William Barr, a Trump appointee, subsequently cleared the president of obstruction of justice after receiving Mueller's report.
In his opening statement, Mueller reiterated that his team had decided not to make a determination on the question of obstruction. "Based on Justice Department policy and principles of fairness, we decided we would not make a determination as to whether the president committed a crime. That was our decision then and remains our decision today," Mueller said.
Nadler said in his opening statement that Mueller conducted the inquiry with "remarkable integrity" and was "subjected to repeated and grossly unfair personal attacks."
"Although department policy barred you from indicting the president for this conduct, you made clear that he is not exonerated. Any other person who acted in this way would have been charged with crimes. And in this nation, not even the president is above the law," Nadler said.
Republican congressman John Ratcliffe accused Mueller of exceeding his authority in the report's extensive discussion of potential obstruction of justice by Trump after the special counsel made the decision not to draw a conclusion on whether Trump committed a crime. Ratcliffe agreed that Trump was not above the law, but said the president should not be "below the law" either.
Republican Collins said the facts of the Mueller report are that "Russia meddled in the 2016 election. The president did not conspire with Russians. Nothing we hear today will change those facts."
"The president watched the public narrative surrounding the investigation assume his guilt while he knew the extent of his innocence," Collins said. "The president's attitude towards the investigation was understandably negative, yet the president did not use his authority to close the investigation."
Republican Representative Steve Chabot said Wednesday's hearing was the "last, best hope" by Democrats "to build up some sort of groundswell across America to impeach President Trump. That's what this is really all about today." Chabot also told Mueller some people thought his report was "a pretty one-sided attack on the president."
Republican Representative James Sensenbrenner noted that Mueller's report never referred to actions by Trump as potentially impeachable conduct.
Before the hearing, Trump complained on Twitter that Mueller had not investigated various of the president's foes including 2016 Democratic presidential candidate Hillary Clinton and, referring to the former special counsel, "HIMSELF." During the hearing, Trump posted a tweet that quoted a Fox News anchor as calling the hearing a "disaster" for Democrats and Mueller's reputation.
Mueller's investigation led to criminal charges against 34 people and three Russian entities. People who were convicted at trial or pleaded guilty included Trump's former campaign chairman and other aides.
With a no-nonsense reputation, Mueller is a Marine Corps combat veteran from the Vietnam War who later served as a federal prosecutor and became the architect of the modern FBI after the Sept. 11, 2001, attacks on the United States.
Mueller served as FBI director from 2001 to 2013 under presidents in both parties.