Longtime FBI investigator Peter Strzok, who was removed from special counsel Robert Mueller’s into investigation Russian meddling after sending derogatory messages about President Trump, reportedly edited a key part of former FBI Director Jim Comey’s statement about Hillary Clinton’s use of a private email server.

U.S. officials told CNN that Strzok, who led the FBI’s probe into Clinton’s private email server, changed the language Comey used to detail Clinton’s actions from “grossly negligent” to “extremely careless.”

Several people looked over the language as changes were being made, but the change from “grossly negligent” to “extremely careless” could have had major consequences. Under federal law, mishandling of classified information through gross negligence is a criminal act.

Strzok also signed the document officially launching the probe into Russia’s interference in the 2016 election, according to CNN.

Senate Judiciary Committee Chairman Chuck Grassley, R-Iowa, accused Comey and other FBI officials last month of eliminating the words “grossly negligent” from the former director’s July 2016 comments on the FBI’s probe into Clinton’s use of a private email server.

“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.

Grassley asked FBI Director Christopher Wray to turn over copies of files of Comey’s remarks in the original form, including “all metadata indicating who created the original drafts, who made the edits to the draft statement, and when those edits were made.”

News of Strzok’s involvement in changing Comey’s remarks come after it was reported he sent texts to a colleague mocking Trump.

The Justice Department’s inspector general was looking into Strzok after the messages were discovered. Strzok had been exchanging texts with Lisa Page, an FBI lawyer who was also part of Mueller’s team.

The two were reportedly involved in an extramarital affair during the FBI’s investigation into Clinton’s use of a private email server.

Strzok was removed from the Mueller probe over the summer.