U.S. Attorney John Durham's inquiry into the Russia investigation is not expected to wrap up until the spring or summer of 2020.

Attorney General William Barr, who is overseeing Durham's work, gave the first hint on Tuesday about when that Justice Department investigation might conclude, one day after the agency's inspector general released a report on the FBI's efforts to monitor a member of President Trump's 2016 campaign.

Emphasizing how Durham's investigators will scrutinize the actions of the Justice Department and the FBI before and after the 2016 presidential election, Barr said Durham's investigators are "looking at the whole waterfront." This includes issues surrounding Crossfire Hurricane, the FBI’s counterintelligence investigation into the Trump campaign, which was later wrapped into special counsel Robert Mueller’s Russia investigation.

“He's looking at the issue of how it got started. He’s looking at whether or not the narrative of Trump being involved in the Russian interference actually preceded July and was in fact the precipitating trigger for the investigation, and he’s also looking at the conduct of the investigation,” Barr told NBC News's Pete Williams. “There are some things that were done in the investigation that are not included in [DOJ Inspector General Michael] Horowitz's report. And he's looking at those things. But also, a few weeks ago, I told him that he should spend just as much attention on the post-election period. And I did that because of some of the stuff that Horowitz has uncovered which to me is inexplicable.”

Horowitz’s investigation focused on allegations of Foreign Intelligence Surveillance Act abuses against onetime Trump campaign associate Carter Page related to the FBI’s reliance on a dossier compiled by British ex-spy Christopher Steele. Horowitz concluded that the FBI’s investigation was filled with serious missteps and the concealment of exculpatory information from the FISA court.

The watchdog said he “did not find documentary or testimonial evidence of intentional misconduct” from the FBI agents and supervisors involved in the FISA process, but “also did not receive satisfactory explanations for the errors or problems we identified.” Horowitz believed FBI agents “substituted their own judgments” in place of FBI leadership and in place of the FISA court when dismissing the significance of new or important facts and said FBI agents “did not follow or appear to even know” many of the FISA rules they were required to follow.

Barr and Durham broke with Horowitz on whether the bureau’s Trump-Russia investigation was properly predicated.

“Their case collapsed after the election, and they never told the court. And they kept on getting renewals on these applications. There were documents falsified in order to get the renewals. There was all kinds of withholding of information from the court,” Barr said. “And the question really is, 'What was the agenda after the election that kept them pressing ahead after their case collapsed?' He's the president of the United States.”

Barr said questions remain unanswered, pointing to former FBI Director James Comey’s refusal to allow his security clearance to be reinstated, which allowed him to avoid the questions about classified information that Horowitz wanted to raise. Durham, who is conducting a criminal investigation, has the ability to compel testimony from other agencies and countries, unlike Horowitz in his limited role as inspector general.

Barr also emphasized that Durham is being meticulous and will leave it to the U.S. attorney to decide whether he will issue a final report or make a public presentation.

“You know, these things take time. And I know there's a lot of impatience. People want results immediately, but those are people who don't understand our process. We have to be careful about the way we collect evidence. And we have to make sure that we have enough evidence to justify our actions. And we're not going to cut corners in that respect,” Barr said. “You know, there's some people who think this thing is going to drop in a few weeks. That's not the case. I see this, perhaps, reaching an important watershed perhaps in the late spring, early summer.”

Barr has become a polarizing figure while overseeing this investigation into the origins of the Trump-Russia investigation, for which Trump gave him full declassification authority, and Democrats have accused him of going to extreme lengths to protect Trump. As part of the investigation, Barr and Durham have reached out to foreign governments, including Australia, Italy, and the United Kingdom, taking multiple overseas trips to speak with intelligence officials and review evidence as they look into how the Trump-Russia investigation began.

Barr defended those trips and his participation in meetings with foreign officials.

“I think our nation was turned on its head for three years. I think based on a completely bogus narrative that was largely fanned and hyped by an irresponsible press. And I think that there were gross abuses of FISA and inexplicable behavior that is intolerable in the FBI,” Barr said. “And the attorney general's primary responsibility is to protect against the abuse of the law enforcement and intelligence apparatus and make sure that it doesn't play an improper role in our political life. That's my responsibility. And I'm going to carry it out.”

