This was Rolling Stone's biggest mistake in their now-retracted UVA story

Rolling Stone published a scathing report from Columbia Journalism School Sunday night, which details the many issues in their discredited article on sexual assault at the University of Virginia.

Rolling Stone officially retracted the UVA article Sunday night, replacing it online with the Columbia report - compiled by journalism school dean Steve Coll. Columbia's investigative report reviewed of Rolling Stone's reporting and editorial decisions, specifically in how the magazine covered the story of UVA student "Jackie," who alleged in the article that she was gang-raped at a campus fraternity house.

Much - if not all - of Jackie's story has now been disproved, by outside media reports, a police investigation, and now the Columbia review.

Jackie told Rolling Stone that she was gang-raped during a date party on September 28, 2012, at the campus' Phi Kappa Psi fraternity house. In Rolling Stone's article, three of the UVA student's friends meet her after she is allegedly raped, telling her to keep quiet to protect both her own reputation and the school's Greek system.

Although it appears that the other students are quoted directly - albeit with pseudonyms - all of their comments are taken from what Jackie told Rolling Stone writer Sabrina Rubin Erdely.

In fact, after the Rolling Stone article was published, all three students came forward independently under their real names to provide alternate accounts of what actually happened that night, telling the Associated Press that they urged Jackie to call the police, with one student even going so far as beginning to dial 9-1-1.

Not speaking to these students, Coll writes, was the biggest mistake that Rolling Stone made:

In hindsight, the most consequential decision Rolling Stone made was to accept that Erdely had not contacted the three friends who spoke with Jackie on the night she said she was raped. That was the reporting path, if taken, that would have almost certainly led the magazine's editors to change plans.

All the friends said that no one from Rolling Stone - including Erdely - ever reached out to them during the course of reporting the story, even though they were quoted in it based on Jackie's comments.

Jackie reportedly asked the magazine to not name or contact the people she described in the story. However, according to the Columbia report, "Jackie never requested ... that Rolling Stone refrain from contacting" the three friends that she said were with her that night, although she did only give the writer their first names.

"All three friends would have spoken to Erdely, they said, if they had been contacted," Coll reports.

He elaborated on this in an interview with Columbia Journalism Review, saying, "the reason it's a single point of failure involves our finding that all this was avoidable through routine practices of journalistic verification."

"Jackie had told the reporter a story about her recent encounters with one of these three, and if the reporter had found them, had reached out to them, even just for the purposes of checking, she would have heard a disturbing contradiction of what Jackie had told her. Essentially one of the three would have said she'd made up a story just a week ago," Coll explains.

Jackie's friends also provided alternate accounts of how the Rolling Stone subject physically appeared on September 28, as well as details about who supposedly had taken her on a date that night.