After FBI agent removed from Mueller's team, FBI utility man steps in

This story has updated.

After Special Counsel Robert Mueller removed a senior FBI agent from his team for allegedly expressing potentially anti-Trump views, a veteran FBI official briefly involved in the launch of the agency's probe into Hillary Clinton's private email server has stepped in to join Mueller's ranks, ABC News has learned.

Agent David Archey is described by colleagues as a utility man of sorts within the FBI.

The FBI later told ABC News he played a fleeting administrative role in the initial opening of the Clinton-related probe. He quietly joined Mueller's team over the summer, according to sources with knowledge of the matter.

While Archey's exact role within the Special Counsel's office remains unclear, some in FBI circles believe he was sent there to replace Peter Strzok, who was brought onboard by Mueller to help manage the far-reaching investigation but removed in early summer. Others questioned whether Archey's enlistment had anything to do with Strzok.

The Justice Department's inspector general, looking into an array of FBI actions tied to last year's election, found text messages from last year sent by Strzok that could be interpreted as critical of Donald Trump, sources told ABC News.

"Immediately upon learning of the allegations, the Special Counsel's Office removed Peter Strzok from the investigation," Mueller spokesman Peter Carr said in a recent statement.

Trump seized on the news, saying in a Tweet on Sunday that the FBI's "reputation is in tatters."

During a House hearing on Thursday with FBI Director Chris Wray, Republicans similarly used Strzok's situation to question the integrity of federal investigations, including the probe being led by Mueller - a Republican himself who was appointed Special Counsel by a Trump nominee.

Strzok has spent much of his law enforcement career working counterintelligence cases, and he has been widely praised by federal law enforcement officials who spoke with ABC News.

He reportedly left Mueller's team in late July and is now working for the FBI's human resources division. At the time of Strzok's departure, Archey was serving as the acting head of the FBI's field office in Birmingham, Alabama.

Archey is "very seasoned and smart," one source who's worked alongside Archey told ABC News. The limited public profile offered of Archey reflects a low-key man who has repeatedly been asked to temporarily step into vacancies within his own agency.

For a brief period in 2015, he served as the acting deputy assistant director of the FBI's counterintelligence division at headquarters in Washington. According to documents released by the FBI, he was one of a small group of senior FBI officials who - on the day that the FBI launched its criminal probe into Hillary Clinton's use of a private email server as secretary of state - approved the move. He was not otherwise involved in the FBI's investigation related to Clinton.

"Whether they are elected or appointed, public officials are servants of the public's interest," Archey said in a press release, unrelated to Clinton, during his time in Alabama. "While the vast majority of public officials are honest, those who are not should know that there is no acceptable level of corruption, and my office is dedicated to rooting out corruption at every level."

Even amid the public spectacle that has engulfed Mueller's investigation - with reporters and photographers chasing prosecutors and others around the nation's capital - the FBI agents behind the sprawling probe have largely remained unseen and unsung.

But with every charge brought by Mueller, an FBI agent working on the case is identified in open court, offering the public another peek at the team of FBI agents working for the Special Counsel.

When former Trump campaign manager Paul Manafort and his deputy, Rick Gates, appeared in court for the first time to face money-laundering charges, prosecutors were accompanied by FBI agent Omer Meisel.

Meisel has known Mueller's top prosecutor, Andrew Weissmann, for several years.

In 2002, after focusing on fraud, insider trading and money laundering from the FBI's San Francisco field office, Meisel was assigned to the FBI task force created to investigate the collapse of energy giant Enron. Weissman was the lead prosecutor on the case.

Each member of the Enron Task Force was "uniquely skilled at drilling deep into balance sheets and following the money," the FBI said in a 2006 summary of the investigation, which lasted five years. "Their job [was] to learn how company officials perpetrated fraud on such a grand scale, build a strong criminal case, and hold accountable those responsible."

Ultimately, top Enron officials were convicted of federal fraud charges and 16 others pleaded guilty to their roles in what the FBI called a "sham accounting" scheme. At the time, it was "the largest and most complex white-collar investigation in FBI history," according to the FBI.

When Trump's former national security, Michael Flynn, admitted in court last week that he lied to FBI agents about his contacts with the Russian government, prosecutors in that case were accompanied by FBI agent William Barnett.

Little is publicly known about Barnett.

Before leaving Mueller's team, however, Strzok had become well-known among reporters covering the FBI.

As chief of the FBI's counterespionage section last year, he helped oversee the FBI's investigation into Hillary Clinton's use of a private email server, and he took part in the bureau's interview of her.

Within weeks of the end of the Clinton probe, Strzok found his office facing a new challenge: investigating Russia's alleged efforts to influence last year's presidential election, including hacking of Democratic National Committee computers.

During the congressional hearing Thursday, Republicans on the House Judiciary Committee repeatedly pressed FBI Director Wray about Strzok and questioned whether Mueller's investigators could be fair and impartial.

"We do not know the magnitude of this insider bias on Mr. Mueller's team," the committee's chairman, Rep. Bob Goodlatte, R-Virginia, said. "One thing is clear though: It is absolutely unacceptable for FBI employees to permit their own political predilections to contaminate any investigation."

Wray balked at such comments.

"Congressman, there is no shortage of opinions out there," Wray said. "What I can tell you is that the FBI that I see is tens of thousands of agents and analysts and staff working their tails off to keep Americans safe from the next terrorist attack, gang violence, child predators, spies from Russia, China, North Korea and Iran. The FBI that I see is tens of thousands of brave men and women who are working as hard as they can to keep people that they will never know safe from harm ... The FBI that I see is people - decent people - committed to the highest principles of integrity, professionalism and respect."

Wray noted that the Justice Department's "outside" and "independent" inspector general is currently looking into allegations related to Strzok and others.

"And when that independent fact-finding is complete, we will hold our folks accountable if that's appropriate," he said.

At the hearing Thursday, Republicans also raised concern that Strzok played a key role in then-FBI Director James Comey's remarks last year announcing that Hillary Clinton would not face charges for her use of a private email server as secretary of state.

After coming to the conclusion that Clinton bore no criminal responsibility, Comey had planned to describe Clinton's actions as "grossly negligent," but based on Strzok's recommendation he changed the phrase to "extremely careless," according to sources with knowledge of the matter.

U.S. law makes such "gross negligence" a federal crime, "but I believe also that almost anybody who grabbed a thesaurus would say that 'gross negligence' and 'extremely careless' are pretty darn close to each other," Wray told lawmakers.

A spokesman for the Special Counsel's office declined to comment for this article. An FBI spokesman also declined comment.

Editor's Note: An FBI spokesman later clarified to ABC News that David Archey was in the acting deputy assistant director position on the day that he and others approved the opening of the FBI investigation into Hillary Clinton's use of a private email server when she was Secretary of State. In documents publicly released by the FBI, Archey is listed as "A/DAD" - Acting Deputy Assistant Director - of the counterintelligence division and "approved" the opening of the full investigation. He left that position shortly thereafter and was not involved in the broader investigation.