When he was named special counsel in May, Robert S. Mueller III was hailed as the ideal lawman — deeply experienced, strait-laced and nonpartisan — to investigate whether President Trump's campaign had helped with Russian meddling in the 2016 presidential election.
The accolades squared with Mueller's valor as a Marine rifle platoon commander in Vietnam and his integrity as a federal prosecutor, senior Justice Department official and FBI director from 2001 to 2013 — the longest tenure since J. Edgar Hoover's. He was praised by former courtroom allies and opponents, and by Democrats and Republicans in Congress.
But at 73, Mueller has a record that shows a man of fallible judgment who can be slow to alter his chosen course. At times, he has intimidated or provoked resentment among subordinates. And his tenacious yet linear approach to evaluating evidence led him to fumble the biggest U.S. terrorism investigation since 9/11.
Now, as he leads a sprawling investigation aimed at the White House, Mueller's prosecutorial discretion looms over the Trump presidency.
On what terms would Mueller offer immunity from prosecution to investigative targets? How broadly will he interpret his mandate to look into not only the 2016 campaign but also matters that "may arise directly from the investigation"?
Will he target Trump's sprawling family business and financial empire and the years before the developer ran for the White House?
Robert Swan Mueller III began life on an elite footing.
Raised in affluent suburbs west of Philadelphia, he attended St. Paul's School in New Hampshire (classmates included future Secretary of State John F. Kerry) before majoring in politics at Princeton. He joined the Marines after graduation and was awarded Navy and Marine Corps medals for his service in Vietnam, where he was shot in the thigh. He graduated from the University of Virginia School of Law in 1973.
Bored by a stint at a white-shoe San Francisco law firm, the jut-jawed Mueller switched to the U.S. attorney's office there in 1976. Colleagues say he typically arrived by 6:30 a.m., at times in his Marine-issue green raincoat. He played on the office softball team but was careful not to let down his guard while socializing.
"He'd join us, have one — and it was only one — and then his wife would arrive to pick him up," recalled a colleague.
This article is based, in part, on interviews with more than two dozen lawyers and investigators who have worked with Mueller. Citing the sensitivity of the Russia investigation and potential repercussions, most spoke on the condition of anonymity. Mueller declined, through a spokesman, to comment.
Mueller also is remembered for a headline-grabbing case that ended in failure.
In 1979, the government lodged then-novel racketeering charges against 33 members of the Hells Angels motorcycle club. The indictments alleged bombings and murders as well as the manufacture and sale of illegal drugs. The defendants and their supporters were so feared that bulletproof glass was installed in court to shield the judge.
The first trial, of 18 defendants, ended with only five convictions. All were overturned on appeal.
Mueller, who led the U.S. attorney's special prosecutions unit, then took over the case. He dropped many of the charges, including those against Ralph "Sonny" Barger, leader of the club's Oakland chapter, whose charismatic testimony had dominated the first trial.
Mueller led a team of four prosecutors in court when the second trial, with 11 defendants, began in October 1980. But after four months, the jury said it was deadlocked, and the judge declared a mistrial. Mueller decided not to ask for a retrial.
Richard B. Mazer, a defense lawyer at both trials, said the government was unable to prove the Hells Angels was a racketeering enterprise. Key prosecution witnesses, he said, seemed unreliable — especially those granted immunity to testify despite having committed violent crimes themselves.
"They made a mess of it," Mazer recalled. "It was an entirely snitch case. It depended entirely on the quality of snitches."
But Mazer and Alan Caplan, another defense lawyer, praised Mueller's straightforward handling of the case. "We fought hard, but I can't conceivably say anything negative about him," Caplan said.
About a year after the case collapsed, a new U.S. attorney in San Francisco chose a prosecutor with more trial experience to head the office's criminal division, a post that Mueller had held for a year.
Mueller responded by transferring to the U.S. attorney's office in Boston. He prosecuted financial fraud, terrorism and public corruption cases for six years, and served as acting U.S. attorney from 1986 to 1987.
One case — involving a Soviet-bloc spy — gave Mueller an early window into U.S.-Russia intrigues.
At the direction of the Justice Department's internal security division, Mueller negotiated a plea agreement with an East German physicist named Alfred Zehe. In February 1985, Zehe admitted in court that he had conspired to deliver U.S. defense information to East German intelligence authorities.
Under the agreement, Zehe was sentenced only to the time he had served in jail after his arrest at a scientific conference in Boston. In turn, he became a bargaining chip for a major spy swap.
"We ultimately got 25 of our people out, including their families," in a trade for Zehe and several other Soviet-bloc spies, recalled a U.S. official involved with the negotiations.
The successful June 1985 exchange helped pave the way, the official said, for a more significant exchange between Washington and Moscow.
In February 1986, officials again faced off for a trade on the so-called Bridge of Spies between East and West Germany. Among those escorted to freedom was Natan Sharansky, the celebrated Russian human rights activist who had served nine years in Soviet prisons.
As the Cold War ended, Mueller moved to "main Justice" in Washington. He easily won his first Senate confirmation after President George H.W. Bush appointed him assistant U.S. attorney general, responsible for the criminal division.
Mueller oversaw investigations of Panamanian leader Manuel Noriega, the 1988 bombing of Pan Am Flight 103 over Lockerbie, Scotland, and Gambino crime family boss John Gotti, among other high-profile cases. But his tendency to command, rather than inspire, came into sharp relief.
"He doesn't invite disagreement," said a former prosecutor who served under Mueller. "He's an order-giver."
He could be harsh on subordinates — sparking resentment when he referred privately to reassigning career lawyers as "moving the furniture."
In 1993, at age 49, Mueller decided to try private practice again, joining Hale and Dorr as a partner in Washington, representing corporate clients.
The money was better, but Mueller was unfulfilled. After two years, he returned to government service — signing on as a homicide prosecutor in the District of Columbia. It was a time of mayhem in the nation's capital, made worse by the scourge of crack cocaine.
Mueller began working with a cold-case squad of Metropolitan Police detectives and FBI agents that sought to bring murderers to justice.
The squad sent applications for search warrants and subpoenas for Mueller's review before seeking a judge's approval. Unlike some prosecutors, Mueller "wouldn't automatically give a signature," recalled one of the investigators.
"He would ask, 'Have you done your work? Do you have your facts?' … He knew what he was asking was the way to make sure everything stood up" in court.
Building cases often entailed forging trust with victims, witnesses and suspects. Relating to both the sympathetic and the unsavory did not play to Mueller's strengths.
"He was a gruff guy, and a lot of times, there wasn't much warmth or ability to really build a bond or connect with a victim-witness," said the same investigator. "There's times when you've got to bond with the suspect to get what you need. His personality wasn't necessarily the best for that."
Nor was Mueller an easy fit with juries in Washington, especially in the freewheeling local Superior Court, where decorum is typically below what judges demand in U.S. District Court.
"In D.C. Superior Court, it's a bit like meatball surgery. It's a bit like a M.A.S.H. unit — it's the unexpected," said one of Mueller's former colleagues. "His strength was not as a M.A.S.H. unit trial lawyer."
Mueller, a Republican, moved back to San Francisco in 1998 after President Clinton appointed him U.S. attorney for the Northern District of California. In July 2001, President George W. Bush nominated him as FBI director, and he won unanimous Senate confirmation. Mueller asked the White House for a delay, however, so he could undergo treatment for prostate cancer.
His first day on the job was Sept. 4, 2001 — a week before hijacked airliners slammed into the World Trade Center, the Pentagon and a field in Pennsylvania in the worst terrorist attack in U.S. history.
At 7 a.m. on Sept. 12, Mueller, then-Atty. Gen. John Ashcroft and other officials arrived for an emergency briefing at the FBI's operations center. The senior agent had been given an hour to prepare while investigators were still combing airline manifests and scouring crash sites.
When Mueller asked a rapid-fire series of questions, the agent replied that accurate information was not yet "established."
"'I want answers, goddamn it!'" Mueller exploded, an official who was present recalled.
Mueller already was coming under siege from critics who questioned why the FBI had not prevented the attacks. Fear spread of a "second wave" terrorist strike.
Mueller countered by announcing plans to reshape the FBI. Its first priority would be to prevent another terrorist attack — not conventional law enforcement.
The vastness of the FBI's challenge emerged within weeks.
A handful of letters laced with powdered anthrax killed five people and sickened 17 others. The government closed congressional office buildings, the Supreme Court and postal facilities as the country braced for further biological terrorism.
But Mueller's FBI struggled for nearly seven years to determine who was responsible — even as he personally managed the case.
"The director was always the leader of the anthrax investigation, period," said Michael Mason, former head of the FBI's Washington field office.
The FBI focused on Steven J. Hatfill, a virologist at the Army's laboratories at Ft. Detrick, Md. In January 2003, Mueller assured congressional leaders in a closed-door briefing that bloodhounds had traced anthrax from the attacks to Hatfill.
But Hatfill had no experience handling anthrax. Nor did he have access to anthrax stored at Ft. Detrick or elsewhere. Years later, the FBI would reject the bloodhound evidence as unreliable.
After media leaks fingered Hatfill, he sued the FBI and the Justice Department on privacy grounds. In June 2008, the government agreed to pay Hatfill about $5.8 million.
Two months later, on Aug. 6, Mueller summoned senior investigators and prosecutors on the anthrax case to his seventh-floor office. The FBI would hold a news conference that afternoon, and he wanted to recap the case's stunning denouement.
Bruce E. Ivins, an Army microbiologist at Ft. Detrick who specialized in handling anthrax, had committed suicide after his lawyers informed him he was about to be charged with murder for the letter attacks.
Evidence showed Ivins had created and held custody of a batch of anthrax traced by DNA to each of the killings. He had spent hours alone in specially equipped labs just before each batch of letters was mailed.
Mueller let others hold the news conference. Some aides who met Mueller that day think he was reluctant to publicly address the missteps with Hatfill, the bloodhounds and the long delay in focusing on Ivins.
"I think he was personally embarrassed," said one. "I would assess him as someone that can't accept the fact that he screwed up."
At FBI headquarters, protecting the director from embarrassment was ingrained.
A case in point unfolded in 2011 — just as the Senate was considering President Obama's request to extend Mueller's expiring term as FBI director by two years.
The FBI's Inspection Division, a unit that scrutinizes bureau operations, conducted a three-week examination of the Directorate of Intelligence, a unit that Mueller had created to carry out the shift in preventing terrorism.
"They inspected it and they wrote the inspection report, and it said the whole thing's broken — set it on fire and start from scratch," said a former official familiar with the report. Another ex-official confirmed the account.
Mueller's top aides saw peril in following normal procedure — forwarding the report to the Justice Department's inspector general for possible follow-up action.
"It was, 'The director will get skewered. We've got to protect him, and we can't issue this,'" the former official recalled.
The aides kept the report in-house, the former official said, by tweaking its language.
"Anywhere it said 'inspection,' they changed it to 'review.' And said this was a review, not an inspection, and therefore they didn't have to issue it to … the inspector general."
Two years later, Mueller — without citing the inspection — informed Congress that he had restructured the Directorate of Intelligence "to maximize organizational collaboration, identify and address emerging threats and more effectively integrate intelligence and operations within the FBI."
During his final months as FBI director, Mueller was again enlisted to help with a thorny matter in U.S.-Russia relations.
In the summer of 2013, the White House asked Mueller to negotiate the release from Russia of Edward Snowden, the former National Security Agency contractor who stole volumes of classified material on U.S. surveillance operations at home and abroad. Snowden had fled to Moscow after leaking the data to journalists.
Unlike the Cold War spy cases, the U.S. did not offer a trade. The Obama administration wanted Moscow to return Snowden as part of a diplomatic "reset," an ultimately unsuccessful effort to improve relations with Russia.
Lisa Monaco, the White House's Homeland Security advisor, tasked Mueller to talk to Alexander Bortnikov, head of Russia's internal security and counter-intelligence service, the FSB.
For at least a week, Mueller called Bortnikov's office, starting at 3 a.m. in Washington. Each time, the FBI director was turned aside without getting Bortnikov on the line.
"Mueller just kept calling over there, like begging to talk to the guy," said a former official. Instead, Snowden was granted asylum in Russia.
The unsuccessful outreach offered Mueller insight into Russian intelligence, which U.S. officials say helped hack and leak Democratic Party emails last year in an effort to undermine U.S. democracy and to help Trump's campaign.
Investigators and lawyers who have worked with Mueller say that his legacy as special counsel will depend, ultimately, on his resolve, his integrity and especially his judgment.
"If he believes somebody has committed a crime, he's going to do whatever he can to hold them accountable," said a former FBI colleague. "Trump's name or brand is not going to back down Mueller."