Attorney General William Barr told Congress on Sunday that special counsel Robert Mueller concluded there was no criminal collusion between the Trump presidential campaign and the Russian government.

Over the course of the years-long Mueller investigation, some of the media's biggest stories resulted in retractions, apologies, and even departures. Some reports, many of which relied on unnamed sources and remain uncorroborated, have never been retracted or corrected. One such story was even refuted by the Special Counsel’s Office in a rare public rebuke.

The fight over Mueller's report is far from over. Democrats are demanding his full report be released to the public and questions remain about whether Trump attempted to obstruct justice.

But Barr explained that Mueller's probe was extensive. He wrote, “the Special Counsel issued more that 2,800 subpoenas, executed nearly 500 search warrants, obtained more than 230 orders for communication records, issued almost 50 orders authorizing use of pen registers, made 13 requested to foreign governments for evidence, and interviewed approximately 500 witnesses.”

Despite all of this investigative work, Mueller never charged anyone in relation to these 10 bombshell reports:

Jan. 10, 2017: CNN reported, “Classified documents presented last week to President Obama and President-elect Trump included allegations that Russian operatives claim to have compromising personal and financial information about Mr. Trump, multiple U.S. officials with direct knowledge of the briefings tell CNN.” These classified documents would eventually be revealed to have been part of what came to be known as the Trump dossier, a series of memos put together by British ex-spy Christopher Steele and then pushed to journalists and members of the government.

Later that day, BuzzFeed published the unverified document in its entirety, saying: “A dossier making explosive — but unverified — allegations that the Russian government has been 'cultivating, supporting and assisting' President-elect Donald Trump for years and gained compromising information about him has been circulating among elected officials, intelligence agents, and journalists for weeks.”

Since that day, much has been learned about the dossier. Its author, Steele, was deemed unsuitable as a human source because of his leaks to the media. His research's funding was revealed to have come through the opposition research firm, Fusion GPS, which itself was funded in part by the Clinton campaign and the Democratic National Committee through the Perkins Coie law firm. Despite being unverified, the dossier was used as a key part of FISA applications against Trump campaign associate Carter Page, which has served as a source of concern for GOP investigators. Its specific source of funding was never revealed to the Foreign Intelligence Surveillance Court and the vast majority of its claims remain unverified.

Recently released court depositions reveal that the unverified dossier was discussed with or passed along to over a dozen journalists as well as many members of the U.S. government.

Proving the central claims of the dossier about Russian collusion, as well as its more salacious elements, remains an incomplete to this day.

June 6, 2017: Prior to ex-FBI Director James Comey’s appearance in front of the Senate Intelligence Committee in June 2017, CNN reported his congressional testimony would contradict President Trump’s claim that Comey told Trump he was not under investigation. CNN was later forced to retract its story, which was based on an anonymous source.

CNN’s original headline read: “Comey expected to refute Trump.” Its revised headline said: “Comey unlikely to judge on obstruction.”

CNN added an “update and correction” to the piece, which stated: “This article was published before Comey released his prepared opening statement. The article and headline have been corrected to reflect that Comey does not directly dispute that Trump was told multiple times he was not under investigation in his prepared testimony released after this story was published.”

June 22, 2017: CNN reported then-White House Director of Communications Anthony Scaramucci was involved with the Russian Direct Investment Fund and that the Senate Intelligence Committee was examining him over a meeting he had during Trump’s transition with Kirill Dmitriev, an executive from the RDIF. This story was based on a single anonymous source.

CNN later retracted and all three employees who were involved with the piece quit.

CNN’s correction said: “On June 22, 2017, CNN.com published a story connecting Anthony Scaramucci with investigations into the Russian Direct Investment Fund. That story did not meet CNN's editorial standards and has been retracted. Links to the story have been disabled. CNN apologizes to Mr. Scaramucci.”

Dec. 1, 2017: ABC News reported former national security adviser Michael Flynn would testify that he was directed by then-candidate Trump to contact Russian officials in the midst of the 2016 campaign. But it was revealed that Flynn’s contacts with the Russians only occurred after the election. ABC News was forced to retract the bombshell, which it said came from an anonymous source.

ABC News would tweet out a correction: “During a live Special Report, ABC News reported that a confidant of Lt. Gen. Michael Flynn said Flynn was prepared to testify that then-candidate Trump instructed him to contact Russian officials during the campaign. That source later clarified that during the campaign, Trump assigned Flynn and a small circle of other senior advisers to find ways to repair relations with Russia and other hot spots. It was shortly after the election, that President-elect Trump directed Flynn to contact Russian officials on topics that included working jointly against the Islamic State."

Dec. 5, 2017: The Wall Street Journal and Bloomberg reported that Mueller had subpoenaed Trump’s bank records from Deutsche Bank, with the Journal naming Trump specifically and Bloomberg claiming that the subpoena had “zeroed in” on the Trumps. Both later issued corrections to their stories. The sources in both instances were anonymous.

The Wall Street Journal’s official correction read: “An earlier sub-headline said a subpoena from special counsel Robert Mueller’s office requested data and documents about President Trump’s accounts. The subpoena concerns people or entities close to Mr. Trump.”

Bloomberg wrote a similar story and was forced to issue a similar correction, saying that their story on Dec. 6th “corrects December 5th story that said subpoena ‘zeroed in’ on Trumps.” The corrected story said only that “those records pertain to people affiliated with President Donald Trump.”

Dec. 8, 2017: CNN reported that Donald Trump Jr. received emails hacked by Russia before WikiLeaks released them in the midst of the 2016 presidential campaign. It seemed like a giant scoop indicating that the president's eldest son was being given advance access to the DNC email dump. But it wasn’t true, since the emails that Don Jr. were sent were already public. CNN later published an extensive correction and update to their article. Their story was based on two anonymous sources.

CNN’s correction read: “This story has been corrected to say the date of the email was September 14, 2016, not September 4, 2016. The story also changed the headline and removed a tweet from Donald Trump Jr., who posted a message about WikiLeaks on September 4, 2016.” With a corrected timeline, the story no longer supported CNN's original claims.

The correction continued: “CNN originally reported the email was released September 4 — 10 days earlier — based on accounts from two sources who had seen the email. The new details appear to show that the sender was relying on publicly available information. The new information indicates that the communication is less significant than CNN initially reported.”

April 13, 2018: McClatchy reported Mueller had evidence that longtime Trump attorney Michael Cohen was in Prague during the 2016 presidential election. This would have lent credence to a claim made in the Steele dossier that Cohen had gone to Prague that summer in an effort to collude with the Russians on election interference. McClatchy’s story was based on two anonymous sources.

McClatchy said: “The Justice Department special counsel has evidence that Donald Trump’s personal lawyer and confidant, Michael Cohen, secretly made a late-summer trip to Prague during the 2016 presidential campaign, according to two sources familiar with the matter.”

The day that the dossier was made public in 2017, Cohen tweeted out a picture of his passport along with a claim that he'd never been to Prague, and he has steadfastly denied the allegation ever since.

Nov. 27, 2018: The Guardian reported Paul Manafort managed to sneak into the Ecuadorian Embassy in London three different times to meet with Julian Assange. The report was never confirmed by other outlets and was dependent on anonymous sources.

The Guardian's report said: “Donald Trump’s former campaign manager Paul Manafort held secret talks with Julian Assange inside the Ecuadorian embassy in London, and visited around the time he joined Trump’s campaign, the Guardian has been told. Sources have said Manafort went to see Assange in 2013, 2015 and in spring 2016 – during the period when he was made a key figure in Trump’s push for the White House.”

Manafort denied this in a statement which read in part: "This story is totally false and deliberately libelous. I have never met Julian Assange or anyone connected to him."

Despite numerous criminal allegations and convictions, Mueller never charged Manafort with anything related to working with WikiLeaks or collusion with Russia.

Dec. 27, 2018: McClatchy followed up on its disputed its Cohen-in-Prague story, reporting that it had evidence of Cohen’s cell phone pinging in Prague at the time that the Trump dossier claimed he was there. The outlet cited four anonymous sources for the story.

McClatchy reported: “A mobile phone traced to President Donald Trump’s former lawyer and ‘fixer’ Michael Cohen briefly sent signals ricocheting off cell towers in the Prague area in late summer 2016, at the height of the presidential campaign, leaving an electronic record to support claims that Cohen met secretly there with Russian officials, four people with knowledge of the matter say.”

Cohen again denied this under oath before Congress last month, saying: "I’ve never been to Prague."

Jan. 17, 2019: BuzzFeed published a bombshell report claiming that Mueller possessed internal emails and testimony that proved that Trump directed Cohen to lie to Congress about a proposed Trump Tower Moscow project. The piece cited anonymous sources.

Jason Leopold and Anthony Cormier, two reporters for BuzzFeed, wrote that “President Donald Trump directed his longtime attorney Michael Cohen to lie to Congress about negotiations to build a Trump Tower in Moscow, according to two federal law enforcement officials involved in an investigation of the matter.”

In a rare move, the Special Counsel’s Office publicly denied the report. Spokesman Pete Carr saying: “BuzzFeed’s description of specific statements to the Special Counsel’s Office, and characterization of documents and testimony obtained by this office, regarding Michael Cohen’s Congressional testimony are not accurate.”

BuzzFeed stuck by the reporting. Speaking with CNN’s Brian Stelter, Cormier said: “We're being told to stand our ground. Our reporting is going to be borne out to be accurate, and we're 100 percent behind it.” And speaking with the New Yorker, Leopold claimed: “I will say that I have evidence that what he said to Congress as it pertains to the story that Anthony Cormier and I wrote was correct.”

Cohen later refuted these claims under oath in front of Congress, writing in his opening statement: "Mr. Trump did not directly tell me to lie to Congress. That's not how he operates."

BuzzFeed's story remains uncorroborated as well as refuted by the Special Counsel's Office. Mueller also never brought any charges against Cohen or anyone else related to these allegations.

It remains to be seen whether Barr’s letter or Mueller’s report will spur retractions for any of the uncorroborated stories.