A May 2016 email from FBI investigator Peter Strzok shows the agency knew at that time some classified information had been hacked from Clinton's private server.
"We did not find documentary or testimonial evidence that improper considerations, including political bias, directly affected the specific investigations we reviewed". The report also notes that then-Attorney General Loretta Lynch repeatedly raised concerns about leaks from NY.
Clinton has blamed her election defeat on Comey's public disclosure of a reopening of the email investigation 11 days before the 2016 election.
While the report being sent to Congress on Thursday doesn't deal with the origins of the probe into Russian Federation meddling in the 2016 US election and possible collusion with those around President Donald Trump, the president and his Republican supporters in Congress are primed to use it as evidence of poor judgment and anti-Trump bias within the Federal Bureau of Investigation and the Justice Department.
A long-awaited watchdog report on the FBI's investigation into Hillary Clinton's emails slams the bureau over the actions of ex-Director James B. Comey Jr. and other agents - but stops short of saying they acted from political bias.
"During the 2016 campaign, Page asked Strzok: "(Trump's) not ever going to become president, right? The report specifically points to Strzok's text message that suggested he would be willing to stop Trump from winning.
The Horowitz report was highly critical of Peter Strzok and Lisa Page, two Federal Bureau of Investigation staff members who exchanged highly charged political messages, finding their texts cast a cloud over the Federal Bureau of Investigation and created the appearance of bias. However, he did say Clinton had been "extremely careless" in her handling of classified information.
The inspector general says he did not follow regulations.More news: Trump Leaves G-7 Summit With A Call To End 'Unfair' Trade
"I do not agree with all of the inspector general's conclusions, but I respect the work of his office and salute its professionalism", Comey wrote in an op-ed for The New York Times after the report's release Thursday.
The FBI can not lawfully make that determination, even if the FBI Agent, in this case Comey, was previously a DOJ prosecutor.
Two Republican-led House committees say their own monthslong probe into the now-closed FBI investigation of Hillary Clinton's emails has so far shown "questionable decision-making" by the agency.
"In the August 8, 2016 text message Page questions whether Trump will become president saying, "[Trump's] not ever going to become president, right?
He also said he didn't know if it was in line with DoJ policy; Horowitz concludes that it wasn't.
Strzok tried to explain to investigators that his message to Page "was meant to reassure Page that Trump would not be elected, not to suggest that he would do something to impact the investigation". "However, I have no faith that those under investigation are also able to provide an unbiased review and edit the IG's work".
The inspector general's report was originally expected in May, and earlier this month, Trump questioned on Twitter whether its publication had been delayed because the findings were "being changed and made weaker".
"Although we acknowledge that Comey faced a hard situation with unattractive choices, in proceeding as he did, we concluded that Comey made a serious error of judgment", the report said of one key moment in the Clinton probe. The pair, who were engaged in a romantic relationship for a period of time, have come under scrutiny by Trump and his allies on Capitol Hill given their brief stints on the special counsel's team.