The report comes 18 months after Horowitz announced that his office would look into alleged misconduct surrounding Comey's handling of the investigation into Clinton's emails, including allegations that DOJ and FBI policies or procedures were not followed.
Horowitz's report also took issue with several FBI employees, whom he said "sent political messages - some of which related directly to the midyear investigation - that created the appearance of bias and thereby raised questions about the objectivity and thoroughness of the midyear investigation".
While a highly anticipated report from inspector general Michael Horowitz will criticize the officials' conduct, he reportedly concluded there is no evidence that they acted improperly or tried to influence the outcome of the investigation.
The exchange references former FBI Director James Comey's decision to reopen the Clinton email probe days before the election, only to close it again.
Democrats - and even Mrs Clinton herself - have blamed Mr Comey for her election loss to US President Donald Trump.
Trump downplays abuses by Kim Jong Un's regime
Trump made the announcement of the freeze at a news conference following the summit and initially appeared to catch U.S. Trump, on the other hand, has promised loudly and repeatedly that this process will end with North Korea's disarmament.
US President Donald Trump and former Federal Bureau of Investigation boss James Comey have traded insults over what Trump perceived to be bias. However, while other reports do implicate McCabe in wrongdoing, the IG says that McCabe "did what he was supposed to do" with regards to his decision not to recuse. "An announcement at that point by the attorney general, especially one without the transparency our traditions permitted, would have done corrosive damage to public faith in the investigation and the institutions of justice". Anticipation builds for report on FBI Clinton probe MORE email probe. Despite this, Comey just had to say something to keep Republicans at bay, so he made up his "extremely careless" remark-something that was both inappropriate and lacked any legal foundation.
On Capitol Hill, members of Congress also reacted to the investigation.
"Strzok told Page in a text message that "we'll stop it", after he was asked, "[Trump's] not ever going to become president, right? The inquiry expanded to touch on an array of politically sensitive decisions by officials including Comey and former Attorney-General Loretta Lynch. He added that "no changes are made to the OIG's report on account of these briefings".
"First, the inspector general's team went through the F.B.I.'s work with a microscope and found no evidence that bias or improper motivation affected the investigation, which I know was done competently, honestly and independently", Comey wrote. The report also noted that once McCabe did officially step back from all Clinton-related probes on November 1, 2016, he "did not fully comply with his recusal in a few instances". When they fixate on the latter, they risk becoming the former.
"As we warned before the election, Director Comey had a double-standard: he spoke publicly about the Clinton investigation while keeping secret from the American people the investigation of Donald Trump and Russian Federation", said top Judiciary Committee Democrat Jerrold Nadler of NY and top Oversight Committee Democrat Elijah Cummings of Maryland in a joint statement.
McCabe's noncompliance with his recusals seemed to be limited mostly to participating in discussions about cases, and the evidence for some incidents was mixed.