In October, documents surfaced that appeared to contradict a key story told by Sen. Elizabeth Warren on the campaign trail. In her telling, Warren’s “dream job” as a public school teacher ended in 1971 when the school principal noticed she was “visibly pregnant,” a form of employment discrimination that was legal and common during that era. On October 7, a conservative website presented archived documents that appeared to challenge that narrative, including the minutes of a meeting in which the school board had voted to extend Warren’s tenure and another in which the board notes that Warren herself resigned from the job.

The story spread like wildfire, moving from conservative publications to major newspapers. Even Kellyanne Conway, a counselor to President Donald Trump, weighed in on the controversy to suggest that the Democratic candidate had lied about her life story. More records seeming to challenge Warren’s narrative emerged, including a 2007 interview in Berkeley, California, in which Warren appeared to say that she left teaching on her own accord to raise her child and seek additional education credentials, as well as a contemporaneous newspaper story about Warren leaving the school “to raise a family.”

Warren has stood by her story that she was “shown the door” because of her pregnancy. “When I was 22 and finishing my first year of teaching, I had an experience millions of women will recognize. By June I was visibly pregnant — and the principal told me the job I’d already been promised for the next year would go to someone else,” Warren said on Twitter last month.

But how did these documents surface in the first place? According to the results of an open records request, an opposition research group known as America Rising had requested documents from the Riverdale Board of Education in New Jersey just weeks before the news appeared. It asked for “Warren’s employment records,” as well copies of other records requested from the school board from the previous two years.

In response to the request, a school official provided America Rising with the school board minutes that became the basis for the story that erupted the following month, along with emails from a Wall Street Journal reporter, who had requested similar records in April.

America Rising — which is affiliated with a political action committee, a public relations firm, and a for-profit research company, as well as several news websites — has been backed over the years by Republican donors, including hedge-fund billionaires Paul Singer and Ken Griffin, private equity investor John Childs, and banker Andrew Beal.

America Rising did not respond to a request for comment. The organization did not claim direct responsibility for the Warren story, but touted the documents as soon as they appeared online via an allied conservative website called the Washington Free Beacon. Free Beacon is also funded by Singer.

America Rising is known for attempting to dig up dirt on politicians, journalists, and activists on behalf of donors’ interests. The group went after journalist Jane Mayer, shopping negative information about the New Yorker writer following the publication of her book “Dark Money.” In 2016, America Rising focused on environmentalist Bill McKibben, dispatching its team to obtain thousands of documents from McKibben’s past and to follow the Vermont-based writer, filming him at public events, as well as while grocery shopping and sitting in a church pew. This year, Definers Public Affairs, an affiliate of America Rising that shares the same staff, decided to rebrand following revelations that the company had been retained by Facebook to orchestrate a campaign to smear its critics.

The current America Rising research effort on Warren appears to be part of a broader dive into the Democratic field, which is being coordinated with America First Policies, the nonprofit arm of Trump’s Super PAC. The effort involves research on Bernie Sanders, Kamala Harris, Michael Bloomberg, Joe Biden, Cory Booker, and other Democratic candidates.

Election narratives are often crafted in part by research efforts financed by partisan interest groups. The board documents surfaced by America Rising don’t necessarily undermine Warren’s version of the events, but they did add to speculation that she embellished her history by opening up a line of questioning that doesn’t have a clear answer.

Politifact, after reviewing evidence of the controversy, did not reach a conclusion one way or another regarding Warren’s claims and her critic’s efforts to unravel them. The principal of the elementary school at the center of the story, Edward Pruzinsky, is deceased.

Still, Warren has argued against some of the claims. The minutes from the April 21, 1971, meeting show that the board unanimously approved a motion to extend Warren’s employment contract as a speech pathologist for the next school year. Another set of board minutes, from June 16, 1971, show Warren’s resignation “accepted with regret.” It is unlikely, as many have pointed out, that Warren showed visible signs of her pregnancy in April of that year. She gave birth to her daughter Amelia in September 1971. Further, if Warren was let go for showing signs of her pregnancy by the summer of that year, it also seems unlikely that the board would highlight that justification in its official set of minutes.

Trudy Randall, a retired teacher who worked at Riverdale Elementary School for three decades, backed up Warren’s account in an interview with CBS News. “The rule was at five months, you had to leave when you were pregnant. Now, if you didn’t tell anybody you were pregnant, and they didn’t know, you could fudge it and try to stay on a little bit longer,” said Randall. “But they kind of wanted you out if you were pregnant.”

That didn’t stop an array of outlets from declaring that Warren had told a lie. “Report disputes Elizabeth Warren’s claim she was let go from teaching job over pregnancy,” claimed the New York Post. The Daily Signal reported, “Records contradict Warren’s claim she was fired for being ‘visibly pregnant.'” On Fox News, the story blared with the chyron, “Warren Facing New Credibility Questions,” with a pundit roundtable that discussed how the documents highlighted a “character issue.”