FBI agent removed from Russia probe played key role in controversial remarks on Hillary Clinton Peter Strzok suggested changes to James Comey's remarks last year.

 -- The veteran FBI agent removed from special counsel Robert Mueller’s team after the discovery of potentially anti-Trump messages also played a key part in former FBI director James Comey’s controversial announcement last year laying out the FBI’s findings in its probe of Hillary Clinton’s use of a private email server, according to a U.S. official with knowledge of the matter.

Specifically, FBI agent Peter Strzok weighed in on drafts of Comey’s July 5, 2016, remarks, recommending that Comey not describe Clinton’s actions as “grossly negligent” but instead as “extremely careless,” according to the official.

As Comey noted at the time, under U.S. law it is a felony to mishandle classified information “in a grossly negligent way.”

“Although we did not find clear evidence that Secretary Clinton or her colleagues intended to violate laws governing the handling of classified information, there is evidence that they were extremely careless in their handling of very sensitive, highly classified information,” Comey said then.

Relevant internal FBI records were turned over to the Senate Judiciary Committee months ago, the official told ABC News.

For months, the Justice Department’s inspector general has been looking into “whether certain underlying investigative decisions” related to the 2016 presidential election “were based on improper considerations,” including “issues that might arise during the course of the review,” according to a statement from the inspector general’s office on Saturday.

In August, ABC News first reported that Strzok, tapped only weeks earlier by Mueller to help lead the probe of Russian meddling in last year's presidential election, had left Mueller's team. Details about the sudden departure were elusive at the time.

But, as initially reported Saturday by The Washington Post and The New York Times, Strzok sent messages during last year’s presidential campaign to a colleague that some believe could be interpreted as critical of then-candidate Donald Trump.

It's unclear if the messages continued after Trump became president and after Mueller was appointed as special counsel in May. Strzok and the person he was texting, identified by The Washington Post as FBI veteran Lisa Page, both ended up on Mueller's team.

Strzok has spent much of his law enforcement career working counterintelligence cases and has been unanimously praised by government officials who spoke with ABC News. He is now working for the FBI's human resources division.

"Immediately upon learning of the allegations, the special counsel's office removed Peter Strzok from the investigation," Mueller spokesman Peter Carr said in a statement Saturday. "Lisa Page completed her brief [assignment] and had returned to the FBI weeks before our office was aware of the allegations."

The Justice Department’s inspector general has been looking into Strzok's actions and indicated in a statement today that the review is part of broader investigations announced in January of how the FBI and Justice Department have handled matters associated with the 2016 presidential election.

"The allegations that the inspector general has confirmed are part of his ongoing investigation, if proven to be true, would raise serious questions of public trust," Attorney General Jeff Sessions said in the statement. "I look forward to receiving the inspector general's report. We will ensure that anyone who works on any investigation in the Department of Justice does so objectively and free from bias or favoritism."

He added that he asked the inspector general to complete the report "as soon as possible" because the "American people deserve answers."

As chief of the FBI's counterespionage section last year, Strzok helped oversee the FBI's investigation related to Clinton, 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 efforts to influence last year's presidential election, including the hacking of Democratic National Committee computers.

CNN first reported Strzok's role in changing language associated with Comey's remarks last year.