Last fall, a largely unknown former prosecutor with a beard and a brisk gait flew unnoticed to Washington from The Hague after being summoned to a secret meeting by Attorney General Merrick B. Garland.
Jack Smith’s job interview would remain unknown to all but a handful of department officials until hours before he was appointed special counsel to oversee two investigations into former President Donald J. Trump in mid-November.
Over the past few months of frenetic activity, Mr. Smith’s anonymity has vanished. He has now indicted Mr. Trump twice: in June, for risking national security secrets by taking classified documents from the White House, and on Tuesday, in connection with his widespread efforts to subvert democracy and overturn an election in 2020 he clearly lost.
And he has taken these actions with remarkable speed, aggressiveness and apparent indifference to collateral political consequences.
“He’s going at a very fast clip — not letting the perfect be the enemy of the good — to the point that I sometimes worry they might be going a little too fast and haven’t buttoned everything up,” said Ryan Goodman, a professor at the New York University School of Law, before the release of the indictment in the election case.
Mr. Smith told reporters that the attack on the Capitol on Jan. 6, 2021, was “fueled by lies” — Mr. Trump’s lies — during brief remarks on Tuesday, after a jury in Washington indicted the former president on four counts.
Mr. Smith is not the first special counsel to investigate Mr. Trump. From 2017 to 2019, Robert S. Mueller III examined ties between Mr. Trump’s 2016 campaign and Russia. In his final report, he laid out a frantic effort by Mr. Trump to thwart a federal inquiry but ultimately cited a Justice Department policy in not making a determination on whether the sitting president had committed a crime. Mr. Smith, by contrast, faces no such limits, given that Mr. Trump is no longer in office.
But where Mr. Mueller took two years to conclude his investigations into Mr. Trump, Mr. Smith — who took over investigations into Mr. Trump that were several months old — delivered his basic assessment in two criminal investigations in a little over eight months.
Beyond the contrast in circumstances and timing, there are undeniable differences between the two men, rooted in their respective ages, experiences, management styles and prosecutorial philosophies, that have shaped their divergent charging decisions.
“His disposition, compared to Mueller, seems very different — he’s working against the clock, Mueller moved a lot more slowly,” said Mr. Goodman, who is a co-founder of Just Security, an online publication that has closely monitored the Trump investigations.
Mr. Trump and congressional Republicans have accused Mr. Smith, without evidence, of pursuing a politically motivated investigation intended to destroy Mr. Trump’s chances of retaking the White House, including by leaking details of the case. But department officials have said Mr. Smith is committed to conducting a fair investigation, and he has defended his own lawyers against attacks from the Trump team, who accuse them of using unethical tactics.
The former president has taken to calling Mr. Smith “deranged,” and some of his supporters have threatened the special counsel, his family and his team — prompting the U.S. Marshals to spend $1.9 million to provide protection for those who have been targeted, according to federal expense reports that cover the first four months of his tenure. Mr. Smith was flanked by a three-person security detail inside his own building when he delivered remarks to reporters on Tuesday.
Mr. Mueller was an established and trusted national figure when he was appointed special counsel, unlike Mr. Smith, who was virtually unknown outside the department and drew a mixed record during his tenure. Mr. Mueller had already solidified a reputation as the most important F.B.I. director since J. Edgar Hoover, after protecting and reshaping the bureau at a time when some were calling for breaking it up following the intelligence failures that preceded the Sept. 11, 2001, terrorist attacks.
But there was, at times, a gap between the perception of Mr. Mueller and his ability to execute a difficult job under fire. Already in his mid-70s, he struck many of those who working with him as a notably diminished figure who, in testifying before Congress at the end of the investigation, was not entirely in command of the facts of his complex investigation.
By comparison, Mr. Smith is someone who rose to the upper echelons of the Justice Department but is not well known outside of law enforcement circles. At 54, Mr. Smith, a lifelong prosecutor, is leading the investigation at the height of his career, not at the end of it.
Mr. Smith is fresh off a stint as a war crimes prosecutor in The Hague and took over two investigations that were already well down the road. Mr. Smith sees himself as a ground-level prosecutor paid to make a series of fast decisions. He is determined to do everything he can to quickly strengthen a case (or end it) — by squeezing witnesses and using prosecutorial tools, such as summoning potential targets of prosecution before a grand jury to emphasize the seriousness of his inquiries, people close to him have said.
When Mr. Smith took over as chief of the Justice Department’s public integrity unit in 2010, the unit was reeling from the collapse of a criminal case against former Senator Ted Stevens, Republican of Alaska. In his first few months on the job, he closed several prominent investigations into members of Congress without charges.
At the time, Mr. Smith brushed off the suggestion that he had lost his nerve. “If I were the sort of person who could be cowed,” he said, “I would find another line of work.”
Among his more notable corruption cases was a conviction of Robert McDonnell, the Republican former governor of Virginia, that was later overturned by the Supreme Court, and a conviction of former Representative Rick Renzi, Republican of Arizona, whom Mr. Trump pardoned during his final hours as president.
Mr. Smith appears to be somewhat more involved than Mr. Mueller in the granular details of his investigations. Even so, he seldom sits in personally on witness interviews — and spoke only sparingly during two meetings with Mr. Trump’s defense lawyers, delegating the discussions to subordinates, according to people familiar with the situation.
Mr. Smith’s stony style, intentional or not, has the effect of sowing considerable unease across a conference table or courtroom.
James Trusty, who quit the former president’s defense team a day after meeting with Mr. Smith’s team in June, worked for years with Mr. Smith as a senior criminal prosecutor at Justice Department headquarters and told associates he was a “serious” adversary not to be underestimated. Other lawyers said Mr. Smith’s team has fed the sense of mystery by describing him in veiled or cryptic terms, with one calling him “the man behind the curtain.”
He has been more public-facing than Mr. Mueller in one critical respect — delivering short, sober statements to the news media after each grand jury indictment.
Mr. Mueller said little when faced with a barrage of falsehoods pushed publicly by Mr. Trump and his allies about him and his investigative team. But at a news conference after Mr. Trump was indicted in the documents case, Mr. Smith seemed to be speaking with an added purpose: to rebut claims that one of his prosecutors, Jay I. Bratt, had inappropriately pressured a defense lawyer representing one of Mr. Trump’s co-defendants, according to a person with knowledge of the situation.
“The prosecutors in my office are among the most talented and experienced in the Department of Justice,” he said. “They have investigated this case hewing to the highest ethical standards.”
While much attention has centered on Mr. Smith, most of the day-to-day work on critical elements of the case has been done by several prosecutors known for their aggressive approaches.
One of them is J.P. Cooney, the former leader of the public corruption division of the U.S. attorney’s office in Washington. Mr. Cooney has worked on several politically fraught trials and investigations that drew the ire of Republicans and Democrats alike.
He unsuccessfully prosecuted two Democrats — Senator Robert Menendez of New Jersey and Greg Craig, a former White House counsel during the Obama administration — and investigated Andrew G. McCabe, the former F.B.I. deputy director, who was vilified by Mr. Trump for the bureau’s Russia investigation. (Mr. McCabe was never prosecuted.)
More recently, Mr. Cooney oversaw the lawyers prosecuting Roger J. Stone Jr., a longtime political adviser to Mr. Trump. The lawyers quit in protest after the Justice Department under William P. Barr intervened in his sentencing. (Mr. Cooney was deeply upset by the intervention, but he said the case was “not the hill worth dying on” according to Aaron Zelinsky, a career prosecutor, who testified before the House Oversight Committee in 2020.)
A second key player is Thomas P. Windom, who was brought in nearly a year before Mr. Smith’s appointment to coordinate the complicated Jan. 6 investigation that had once been seated in the U.S. attorney’s office in Washington.
Mr. Smith has relied on F.B.I. agents to perform investigative tasks, which is not uncommon for special counsels. But the F.B.I. is not walled off from Mr. Smith’s investigation, unlike the agents who were detailed to work for John H. Durham, a special counsel who investigated the origins of the F.B.I.’s Russia investigation.
In a letter to House Republicans in June, Carlos F. Uriarte, the Justice Department’s legislative affairs director, disclosed that Mr. Smith employed about 26 special agents, with additional agents being brought on from “time to time” for specific tasks related to the investigations.
Mr. Smith, unlike many previous special counsels, did not hire most of the staff: He inherited two existing Trump investigations and moved them from Justice Department headquarters to his new office across town. Some of the investigative legwork was also done by investigators with the U.S. Postal Inspection Service and agents with the Justice Department’s inspector general working alongside Mr. Windom at one point.
He has, however, exerted direct control over both inquiries, trying to keep even the most quotidian information about his efforts away from the news media, and been present, if sotto voce, at the most critical moments.
During Mr. Trump’s arraignment in Miami in June, Mr. Smith sat in the gallery, closely watching the proceedings. Some in the courtroom suggested he stared at Mr. Trump for much of the hearing, sizing him up.
But that was not really the case. He listened intently to the lawyers on both sides, at times leaning in toward a colleague to make a whispered comment or ask a question.
Alan Feuer contributed reporting.