Peter Strzok, the FBI agent who was removed from special counsel Robert Mueller’s probe for sending text messages critical of President Donald Trump, helped write the letter informing Congress that the FBI would reopen its investigation into Hillary Clinton’s use of a private email server while Secretary of State. Strzok wrote what appears to be the first draft of the letter former FBI Director James Comey sent to Congress. CNN obtained emails confirming Strzok's involvement.

The revelation about Strzok's involvement comes as Congressional Republicans––and many of the president's supporters––latch onto his text message exchanges with fellow FBI agent Lisa Page. These critics have accused Strzok of being sympathetic to Clinton, and view him as an example of anti-Trump bias at the FBI during the 2016 presidential election. Strzok was removed from the Mueller probe last year. President Trump accused Strzok of "treason" in a Wall Street Journal interview.

Strzok was, according to an individual familiar with his thinking, deeply involved in the Clinton investigation and pursued it "aggressively." In an October 27, 2016, email obtained by CNN, Strzok informs his colleagues he and another FBI agent had drafted "the first cut" of the letter.

Strzok's colleagues exchanged two more emails referencing further comments and changes to Strzok's initial draft, which was ultimately forwarded to Comey by James Rybicki, then the FBI's Chief of Staff.

CNN notes:

One of the drafts, reviewed by CNN, was recently produced to Congress with the email chain. But it is unclear whether that draft was the initial copy written by Strzok or one incorporating others' edits. That draft states that the FBI had an "obligation to take appropriate investigative steps to review" the newly discovered emails on Weiner's laptop.

The next day, on October, 28, 2016, Comey sent the final letter to Congress, editing out the line that he had an "obligation" to take steps to review. Instead, new language was added saying that Comey had been briefed by his team "yesterday" and that he "agreed that the FBI should take appropriate investigative steps."

The key line noting that the "FBI has learned of the existence of emails that appear to be pertinent to the investigation" appears in both the final version and the earlier draft reviewed by CNN.

The letter sparked national controversy immediately after its release, and former Attorney General Eric Holder argued that Comey broke protocol when he wrote about reviewing the newly located emails, which were found on former Congressman Anthony Weiner’s laptop. (Weiner is the estranged husband of Clinton aide Huma Abedin.) Individuals familiar with the case who spoke to reporters at the time, said FBI officials stumbled across the emails "weeks ago" but did not inform Comey of their existence until the week before he presented the findings to Congress. Comey’s announcement came 11 days before the general election; in July 2016, he recommended that the Justice Department bring no charges against Clinton.

The FBI, wrote Holder, “has a practice of not commenting on ongoing investigations. Indeed, except in exceptional circumstances, the department will not even acknowledge the existence of an investigation. The department also has a policy of not taking unnecessary action close in time to Election Day that might influence an election’s outcome. These rules have been followed during Republican and Democratic administrations.”

The rules, he notes, “aren’t designed to help any particular individual or to serve any political interest.” Instead, they “are intended to ensure that every investigation proceeds fairly and judiciously; to maintain the public trust in the department’s ability to do its job free of political influence; and to prevent investigations from unfairly or unintentionally casting public suspicion on public officials who have done nothing wrong.”

Holder also questions the timing of Comey’s announcement: “I fear he has unintentionally and negatively affected public trust in both the Justice Department and the FBI. And he has allowed — again without improper motive — misinformation to be spread by partisans with less pure intentions,” he wrote. “Already, we have learned that the importance of the discovery itself may have been overblown. According to the director himself, there is no indication yet that the “newly discovered” emails bear any significance at all. And yet, because of his decision to comment on this development before sufficient facts were known, the public has faced a torrent of conspiracy theories and misrepresentations.”