A special prosecutor found that the FBI rushed into its investigation of ties between Russia and Donald Trump’s 2016 campaign and relied too much on raw and unconfirmed intelligence as he concluded a four-year probe that fell far short of the former president’s prediction that the “crime of the century” would be uncovered.

The report Monday from special counsel John Durham represents the long-awaited culmination of an investigation that Trump and allies had claimed would expose massive wrongdoing by law enforcement and intelligence officials. Instead, Durham’s investigation delivered underwhelming results, with prosecutors securing a guilty plea from a little-known FBI employee but losing the only two criminal cases they took to trial.

The roughly 300-page report catalogs what Durham says were a series of missteps by the FBI and Justice Department as investigators undertook a politically explosive probe in the heat of the 2016 election into whether the Trump campaign was colluding with Russia to tip the outcome. It criticized the FBI for opening a full-fledged investigation based on “raw, unanalyzed and uncorroborated intelligence,” saying the speed at which it did so was a departure from the norm. And it said investigators repeatedly relied on “confirmation bias,” ignoring or rationalizing away evidence that undercut their premise of a Trump-Russia conspiracy as they pushed the probe forward.

“Based on the review of Crossfire Hurricane and related intelligence activities, we conclude that the Department and the FBI failed to uphold their important mission of strict fidelity to the law in connection with certain events and activities described in this report,” the document states.

The impact of Durham’s report, though harshly critical of the FBI, is likely blunted by Durham’s spotty prosecution record and by the fact that many of the seven-year-old episodes it cites were already examined in depth by th e Justice Department’s inspector general. The FBI has also long since announced dozens of corrective actions. The bureau outlined those changes in a letter to Durham on Monday, including steps meant to ensure the accuracy of secretive surveillance applications to eavesdrop on suspected terrorists and spies.

“Had those reforms been in place in 2016, the missteps identified in the report could have been prevented. This report reinforces the importance of ensuring the FBI continues to do its work with the rigor, objectivity, and professionalism the American people deserve and rightly expect,” the FBI said in a statement. It also stressed that the report focused on the FBI’s prior leadership, before current Director Christopher Wray took the job in 2017.

Still, Durham’s findings are likely to amplify scrutiny of the FBI at a time when Trump is again seeking the White House as well as offer fresh fodder for congressional Republicans who have launched their own investigation into the purported “weaponization” of the FBI and Justice Department. After the report was released, Republican House Judiciary Committee Chairman Jim Jordan said he had invited Durham to testify next week.

Trump, on his Truth Social platform, claimed the report showed the American public had been “scammed.”

Durham, the former U.S. Attorney in Connecticut, was appointed in 2019 by Trump’s attorney general, William Barr, soon after special counsel Robert Mueller had completed his investigation into whether the 2016 Trump campaign had colluded with Russia to move the outcome of the election in his favor.

The Mueller investigation resulted in roughly three dozen criminal charges, including convictions of a half-dozen Trump associates, and concluded that Russia intervened on the Trump campaign’s behalf and that the campaign welcomed the help. But Mueller’s team did not find that they actually conspired to sway the election, creating an opening for critics of the probe — including Barr himself — to assert that it had been launched without a proper basis.

The original Russia investigation was opened in July 2016 after the FBI learned from an Australian diplomat that a Trump campaign associate named George Papadopoulos had claimed to know of “dirt” that the Russians had on Democratic candidate Hillary Clinton in the form of hacked emails.

But revelations over the following months laid bare flaws with the investigation, including errors and omissions in Justice Department applications to eavesdrop on a former Trump campaign aide, Carter Page, as well as the reliance by the FBI on a dossier of uncorroborated or discredited information compiled by an British ex-spy, Christopher Steele.

Durham’s team delved deep into those mistakes, finding that investigators opened the investigation hastily, without doing key interviews or a significant review of intelligence databases. The report says the FBI, at the time the investigation was opened, had no information that any Trump campaign officials had been in touch with any Russian intelligence officials.

It said the FBI did not corroborate a “single substantive allegation” in the so-called Steele dossier and ignored or rationalized what it asserts was exculpatory information that Trump associates had provided to FBI confidential informants. That includes, the report said, minimizing the importance of a conversation in which Papadopoulos strenuously denied to the FBI informant that he had any knowledge of ties between the campaign and Russia.

“An objective and honest assessment of these strands of information should have caused the FBI to question not only the predication for Crossfire Hurricane, but also to reflect on whether the FBI was being manipulated for political or other purposes,” the report said. “Unfortunately, it did not. “

Durham’s mandate was to scrutinize government decisions, and identify possible misconduct, in the early days of the Trump-Russia probe. His appointment was cheered by Trump, who in a 2019 interview with Fox News said Durham was “supposed to be the smartest and the best.” He and his supporters hoped it would expose a “deep state” conspiracy within the top echelons of the FBI and other agencies to derail Trump’s presidency and candidacy.

Durham and his team cast a broad net, interviewing top officials at the FBI, Justice Department and CIA. In his first year on the job, he traveled with Barr to Italy to meet with government officials as Trump himself asked the Australian prime minister and other leaders to help with the probe. Weeks before his December 2020 resignation as attorney general, Barr appointed Durham as a Justice Department special counsel to ensure that he would continue his work in a Democratic administration.

The slow pace of the probe irked Trump, who berated Barr before he left office about the whereabouts of a report that would not be released for several more years. By the end of the Trump administration, only one criminal case had been brought, while the abrupt departure of Durham’s top deputy in the final months of Trump’s tenure raised questions about whether the team was in sync.

Despite expectations that Durham might charge senior government officials, his team produced only three prosecutions. A former FBI lawyer pleaded guilty to altering an email the FBI relied on in applying to eavesdrop on an ex-Trump campaign aide. Two other defendants — a lawyer for the Clinton campaign and a Russian-American think tank analyst — were both acquitted on charges of lying to the FBI.