(CNN) There's a hotly anticipated new report expected to be released Monday from the Department of Justice Inspector General's office about whether, as President Donald Trump has repeatedly alleged, the FBI spied on his presidential campaign in 2016.

That conspiracy theory has helped feed Trump's distrust of the government he leads, and it's been a main counterargument of Republicans who want to divert attention from Trump's behavior as documented in the House impeachment inquiry and Robert Mueller's special counsel report

The investigations and reports are getting hard to keep track of, so CNN's Crime and Justice reporter David Shortell walked us through what to expect from this report and how important it will or won't be.

The DOJ Inspector General Michael Horowitz is expected to release a report Monday. What do we expect it will say? Did the FBI spy on Trump's campaign as he alleges?

The report is not expected to confirm Trump's allegation. Here are a few of the expected top lines, according to reporting from CNN and other outlets:

Horowitz found no evidence that US intelligence agencies tried to plant spies in the Trump campaign;

The FBI had sufficient information to open the Russia investigation in the summer of 2016;

The FBI's applications to the FISA court to surveil former Trump campaign foreign policy adviser Carter Page were valid, but there were some missteps, and potentially illegal conduct, by lower-level employees as part of that process;

The FBI properly appropriately disassociated itself from Christopher Steele, the former British spy and author of the infamous dossier, after his contacts with the media were uncovered.

How big a deal is this?

Shortell: There have been a lot of people in Washington and across the country waiting for this report. It really amounts to the most comprehensive review of the FBI's internal decision-making in the extraordinarily fraught period of time ahead of the 2016 election. In its 400-some pages we expect a lot of answers to important questions about surveillance of members of the Trump campaign and allegations of bias among the FBI leadership. These are topics that the President loves to talk about: the Steele dossier, " There have been a lot of people in Washington and across the country waiting for this report. It really amounts to the most comprehensive review of the FBI's internal decision-making in the extraordinarily fraught period of time ahead of the 2016 election. In its 400-some pages we expect a lot of answers to important questions about surveillance of members of the Trump campaign and allegations of bias among the FBI leadership. These are topics that the President loves to talk about: the Steele dossier, " Spy-gate ," FISA abuse . While all the reporting -- from CNN and other outlets -- indicates that DOJ Inspector General Michael Horowitz will knock down several of the claims that Trump has pushed about abuses at the FBI, there is still going to be criticism of law enforcement and wrongdoing uncovered that will certainly be weaponized by conservative allies of the White House.

Expect this report to be used as a political shield by Republicans getting pummeled every day in the impeachment inquiry.

It's almost 2020. Why are we still talking about the 2016 election?

Shortell: Good question. Well the 2016 election, and the epic FBI investigations that loomed over it, are still things that the President loves to talk about. But this report has been in the works since March of 2018, when the topics seemed a bit more relevant. At the time, Good question. Well the 2016 election, and the epic FBI investigations that loomed over it, are still things that the President loves to talk about. But this report has been in the works since March of 2018, when the topics seemed a bit more relevant. At the time, Horowitz's office said it launched the review after requests from then-attorney general Jeff Sessions and members of Congress. This was just after the so-called Nunes Memo was released -- one of the first kind of after action-reports into the period that shed light on claims of surveillance abuses that drew sharp outcry from Republicans. So to answer your question, things in Washington just take a long time.

This sounds a lot like the investigation Attorney General William Barr opened up into the Russia probe. Is it the same thing?

Shortell: Yes and no. There is overlap in the topics scrutinized in the Horowitz report and by investigators in the separate probe that Barr tapped veteran prosecutor John Durham to lead earlier this year. But Durham's review of the surveillance techniques used by intelligence agencies around the opening of the FBI's investigation is, by design, able to go further and cut deeper. Whereas Horowitz, as the DOJ IG, is only allowed to compel testimony from current department employees, Durham will have greater access to speak with former officials and people who work for the intelligence agencies, like the CIA. In fact, Trump ordered his intelligence agencies to assist in the Durham review earlier this year, giving Barr authority to declassify sensitive secret material. The Durham probe is also now a full-fledged criminal investigation, meaning he can subpoena witnesses, convene a grand jury and file criminal charges.

What do we know about how the report was conducted? How many people they interviewed, etc.?

Shortell: Horowitz is known for being thorough and fair. His office has said they reviewed more than 1 million records and conducted Horowitz is known for being thorough and fair. His office has said they reviewed more than 1 million records and conducted more than 100 interviews ahead of the report. Among the people his investigators met with are some of the current and former law enforcement officials whose names are at the center of "deep state" conspiracies including Steele, and the pair of high-ranking FBI officials, Peter Strzok and Lisa Page, who left the agency under a pall when their anti-Trump text messages were revealed.

There was some controversy, however, in recent weeks after allegations that Horowitz's office was hurrying witnesses as they were being given an opportunity to provide comment on sections of the report that mentioned them, leading to criticism that the report's accuracy was being risked in the rush to release the document. In response, a spokeswoman for the IG's office said at the time that they were clarifying to witnesses that they would be able to provide fulsome written rebuttals to the report, in line with past practices and procedures to protect classified information.

Trump said the Mueller report exonerated him when it didn't. What's he likely to say about this report?

Shortell: One part of the report Trump is certain to seize on is an allegation that a former FBI lawyer altered a document related to the FBI's surveillance of Page. The lawyer is under criminal investigation and his conduct is being reviewed by Durham. One part of the report Trump is certain to seize on is an allegation that a former FBI lawyer altered a document related to the FBI's surveillance of Page. The lawyer is under criminal investigation and his conduct is being reviewed by Durham. CNN first broke the story last month

Trump could use the misconduct as evidence that FBI officials were abusing their power and carrying out an unlawful investigation of his campaign because they were biased against him. But that conclusion would likely fly in the face of Horowitz's own findings, which are expected to not bear that out.

We've also heard Trump begin to dial back expectations in recent days and steer interest towards the Durham report. In London this week he told reporters, "I do think the big report to wait for is going to be the Durham report. That's the one that people are really waiting for."

What about Barr? If he is overseeing his own inquiry that touches on these topics is he likely to be supportive of this IG report?

Barr has only had the highest praise for Horowitz in public, calling him last month a "superb" and "fiercely independent investigator" whose report "will be a credit to the department." But behind closed doors, Barr is telling allies that the Horowitz report won't be the last word on the subject.