A slew of FBI and DOJ officials could face a reckoning when Justice Department Inspector General Michael Horowitz on Thursday releases a long-awaited report detailing his review of the Hillary Clinton investigation during the 2016 presidential race.

“I think it's going to put a lot of the missing pieces in this giant puzzle together,” House Judiciary Committee Chairman Bob Goodlatte, R-Va., predicted Wednesday on Fox News’ “America’s Newsroom.”

For more than a year, Horowitz has been reviewing the FBI and DOJ’s actions related to its investigation into Clinton’s use of a private email server while she was secretary of state.

The report is not expected to address the DOJ and FBI’s actions taken in the Trump-Russia investigation, or relitigate the Clinton case itself. But it will mark the most definitive accounting of the email probe to date, looking at -- among other things -- whether “certain underlying investigative decisions were based on improper considerations.”

DOJ TO RELEASE LONG-AWAITED REVIEW OF CLINTON PROBE ON THURSDAY

Among the top Justice Department and FBI officials expected to face scrutiny in Horowitz’s report: former FBI Director James Comey, then-Attorney General Loretta Lynch, former Deputy FBI Director Andrew McCabe and FBI official Peter Strzok.

James Comey

Horowitz’s investigation has looked at whether it was improper for Comey to make a public announcement about not recommending prosecution over the Clinton email arrangement. He memorably faulted Clinton and her associates for being “extremely careless” with classified information.

A draft version of the report called Comey "insubordinate," calling him out for making that statement as well as notifying Congress the probe was being reopened days before the election, according to ABC News.

Comey, in his newly released memoir, also admitted drafting a statement exonerating Clinton months before federal investigators interviewed the former secretary of state as part of the email probe.

Comey has used his book to defend the move, describing it as a routine step that any competent investigator might take. “Any investigator or prosecutor who doesn’t have a sense, after nearly a year of investigation, where their case is likely headed, is incompetent,” Comey wrote in his book.

Republicans have raised questions about the draft statement essentially clearing Clinton in the email case. It was written before investigators interviewed Clinton and other key figures. It's unclear whether Horowitz's report will take issue with that statement.

Comey has also faced questions about why the FBI waited weeks to act after the 2016 discovery of thousands of emails on ex-Rep. Anthony Weiner's laptop that potentially were relevant to the Hillary Clinton email investigation. The Weiner emails jolted the 2016 presidential race after Comey told Congress just days before the election that FBI agents had found more of Clinton’s messages. The IG review reportedly will hit FBI leaders for moving too slowly after the messages were found.

Loretta Lynch

Horowitz is likely to scrutinize then-Attorney General Loretta Lynch’s infamous meeting on an Arizona tarmac with former President Bill Clinton just days before the FBI decided it would not recommend criminal charges against Hillary Clinton.

Lynch has claimed she and Clinton spoke of only “innocuous things” during their controversial meeting on a tarmac in Arizona, calling it a “chance encounter.”

But the tarmac meeting fueled Republican complaints that Lynch had met with the husband of an investigation subject improperly, just days before the probe into her personal email server was completed with no charges filed.

Comey has publicly taken issue with the meeting, saying the tarmac meeting was a “deciding factor” in his decision to act alone to update the public on the status of the Clinton probe.

Andrew McCabe

Horowitz’s review has already put McCabe in legal jeopardy. The Justice Department’s internal watchdog sent a criminal referral for McCabe in April to the U.S. attorney’s office in Washington after Horowitz’s finding that McCabe leaked a self-serving story to the press and later lied about it to Comey and federal investigators. Attorney General Jeff Sessions fired him in March.

A portion of that report on McCabe was previously released to Congress, but more information involving the former deputy director is likely in Horowitz’s report.

Horowitz also is reviewing whether McCabe should have recused himself from the probe early because of his family’s ties to the Democratic Party. (He did not do so until a week before the election.) And he could face scrutiny over the delay in reviewing messages on Weiner's laptop. McCabe knew as early as September 2016 of the emails, but the bureau did not obtain a warrant to review them until the following month.

This week, lawyers representing McCabe filed a suit against the Justice Department and FBI on Tuesday, alleging that they wouldn't give up files connected to his ouster.

Peter Strzok

The inspector general’s review months ago uncovered a trove of anti-Trump texts from FBI official Peter Strzok, who famously called Trump an “idiot” and texted about an “insurance policy” against a Trump presidency.

Strzok was reassigned to the FBI's human resources division following revelations that he was romantically involved with FBI employee Lisa Page and exchanged the politically charged texts. Page has since left the bureau.

Strzok, a former deputy to the assistant director for counterintelligence at the FBI, also was involved in changing Comey’s early draft language about Clinton’s actions regarding her private email server from “grossly negligent” to “extremely careless.”

Republicans are expected to seize on the report’s findings and argue the existence of an anti-Trump bias.

“I think it's most important that the American people see this report because I think it's going to shed light on how the Federal Bureau of Investigation mishandled this whole investigation with regard to former secretary of state and presidential candidate Hillary Clinton,” Goodlatte said.

But Democrats are already pushing back.

“I’m calling it now: no matter what the DOJ IG report actually says, President Trump’s sycophantic supporters will try to claim that somehow he is the victim of FBI wrongdoing & bias,” Connecticut Democratic Sen. Richard Blumenthal tweeted Wednesday. “Talk about fake news.”

Fox News’ Brooke Singman, Elizabeth Zwirz, Catherine Herridge, Nicole Darrah and Judson Berger contributed to this report.