Editor's note: This story contains a graphic description of an alleged sexual assault.

Tara Reade, a former junior staffer in Joe Biden's Senate office, has accused the presumptive Democratic presidential nominee of sexually assaulting her in 1993, when she was working as a staff assistant. The Biden campaign denies the accusation and says the alleged incident "absolutely did not happen."

Reade detailed her account in multiple conversations with NPR, and it was corroborated by a friend of hers who declined to be identified. Reade's brother also corroborated some parts of her story. No contemporaneous notes or documentation of the alleged incident have been found, and Reade's account has been denied by longtime Biden staffers whom she worked for at the time.

In interviews with NPR, Reade, now 56 and living in California, said the alleged assault happened when she was asked by her then-supervisor to deliver a duffel bag to Biden as he was heading to the Capitol.

When Reade met up with the senator, she said, he pinned her up against a wall and penetrated her vagina with his fingers.

"His hands went underneath my clothing and he was touching me in my private areas and without my consent," Reade told NPR. She said Biden asked her whether she wanted to go somewhere else.

Reade said that she pulled away and that Biden pointed his finger at her and said, "You're nothing to me, nothing."

Reade thinks she must have responded emotionally, because, she said, Biden then took her by the shoulders and said, "You're OK. You're fine. You're OK," before grabbing his bag and walking away.

Reade could not recall the exact location or date of the alleged incident but said it was likely in the basement of a Senate office building in the spring of 1993.

Reade says she filed a police report just over a week ago with the Washington, D.C., Metropolitan Police Department because she was worried about her safety after receiving "online harassment."

The police investigation is currently open, though the statute of limitations for prosecuting the alleged assault has expired.

NPR obtained confirmation of the police report from a law enforcement source. A record of the report names Biden. NPR has filed a Freedom of Information Act request for the full report.

Some details of Reade's account have been inconsistent, and her story has changed over time. In spring 2019, she came forward with an account of Biden touching her shoulder and neck in a way made her feel uncomfortable, but she never mentioned sexual assault. Then in late March of this year, she went on a left-leaning podcast, The Katie Halper Show, and gave a graphic account of sexual assault similar to what she has told NPR. The story took off on left-wing and right-wing corners of the Internet.

Some supporters of the former vice president, suggest Reade has a political motive. They have tried to discredit her by pointing to her changing story, as well as her outspoken support for Bernie Sanders, who was Biden's final presidential primary challenger. Reade also had demonstrated support for candidates Elizabeth Warren and Marianne Williamson, both of whom had earlier dropped out of the race.

Other critics have pointed to her effusive online posts praising the Russian leader Vladimir Putin; Reade says she was enamored with Russia while writing a novel and has publicly walked back those statements. And yet others have questioned why, as recently as 2017, she had taken to the Internet to praise Biden.

Reade wonders why any of that information is relevant in assessing a sexual assault allegation.

"This isn't a partisan issue. This is about power and the abuse of power, and the people around that person that enabled that behavior," she told NPR.

Reade described herself as a third-generation Democrat and said she supports the work Biden did to advocate for the the Violence Against Women Act. She's a domestic abuse survivor and said that legislation personally helped her.

"Many things can be true at once. Someone can do something really awesome, then they can also commit a crime," Reade said, describing her conflicting feelings about Biden.

Reade said she voted for the Obama-Biden ticket twice but does not intend to cast a vote for president this November.

"I personally do not want Trump to become president again. I will not vote for a Republican," she said. "However, I am not going to vote for the person who assaulted me this time ... So where it leaves me is politically homeless, essentially."

Reade's allegation emerged as Biden was securing his position as the presumptive Democratic nominee to take on President Trump in November. More than a dozen women have publicly accused Trump of various incidents of sexual assault. Reade is the only woman to have publicly accused Biden of sexual assault.

Last spring, before Biden jumped into the presidential race, a former Nevada state legislator named Lucy Flores said Biden once grabbed her shoulders, sniffed her hair and gave her an unwanted kiss on her head. "His behavior wasn't violent or sexual, it was demeaning and disrespectful," Flores wrote in March 2019, noting a key distinction. Other complaints of Biden invading women's personal space followed.

Reade was one of the women who came forward with a similar account then, but did not raise an accusation of sexual assault publicly until March of this year.

Reade said she told one of her friends about the alleged 1993 assault around the time she said it happened. That friend, who asked to remain anonymous in part to protect her business interests, spoke with NPR and corroborated Reade's description of the assault and its aftermath.

That friend said she discouraged Reade from going to the police at the time, believing in that era that it would not have resulted in any action and could have hurt Reade professionally.

Reade said she also told her mother, who has since passed away, and her brother, Collin Moulton.

Moulton did not respond to NPR's initial requests for comment, but in a text message on Saturday night said he recalled Reade telling him about an incident in the early 1990s that happened when she was asked to bring Biden a gym bag.

"They were alone in a private area or room. He more or less cornered her against the wall. He put his hands 'under her clothes.' My mom wanted her to go to the police," Moulton wrote.

Moulton also backed up Reade's recollection that she was fired. NPR could not otherwise confirm the circumstances of Reade's departure from the office.

Reade said she never told anyone in Biden's office about the assault, though she said she did complain about harassment, saying she felt uncomfortable on multiple occasions because of Biden and his staff. Reade said Biden would run his hands through her hair at meetings and said she was asked to serve drinks at a fundraiser because the senator apparently liked her legs. Moulton said in his text message that Reade told him about such incidents.

NPR spoke with multiple former Biden staffers from the time, and none of them could confirm Reade's recollections.

Melissa Lefko had the same job as Reade in the early 1990s, both serving as staff assistants in roughly the same time period. Lefko told NPR that the position did not involve the kind of regular interactions with Biden that Reade has at times described and that she was never asked to take the senator personal items or attend fundraisers. Lefko said the job entailed answering phone calls and performing constituent services.

Lefko added that she does not personally remember Reade and that Reade's description of the office environment doesn't align with her experience.

"The culture of the office was very professional in every way, with women in senior positions at a time when that was not the norm," said Lefko. "When you work on the Hill, you know who the good guys are and who the bad guys are. And Biden was a good guy, and I mean that wholeheartedly."

Although Reade said she never spoke about the assault to anyone on Biden's staff, she said she filed a formal written complaint about harassment to a Senate personnel office but did not receive any follow-up. She did not have a copy of the complaint and said she could not recall the name of the office where she had filed paperwork.

Reade also said she reported her concerns about harassment to three people in the office: Biden's longtime aide, Dennis Toner; his then-chief of staff, Ted Kaufman; and his executive assistant, Marianne Baker. Reade recalls having multiple conversations and meetings with them about the alleged harassment.

Both Toner and Kaufman told NPR they had no recollection of Reade. Congressional files confirm she worked in the office for about nine months from December 1992 to August 1993.

"She did not come to me," Kaufman said. "I would have remembered if she had."

Kaufman stepped in to fill Biden's Senate seat when he became vice president in 2009 and remains a close confidant.

Toner, who worked for Biden for 34 years, told NPR the same. "I would recall any conversation with any staff member with Senator Biden that was along the lines of sexual harassment," he said.

"It's something that would be so out of character with how you would describe Joe Biden," Toner added, reiterating that he has never heard any other such complaints from other staff.

Baker worked for Biden for 18 years and, in a statement sent from the Biden campaign, said she took her duties related to human resources very seriously: "In all my years working for Senator Biden, I never once witnessed, or heard of, or received, any reports of inappropriate conduct, period — not from Ms. Reade, not from anyone. I have absolutely no knowledge or memory of Ms. Reade's accounting of events, which would have left a searing impression on me as a woman professional, and as a manager. These clearly false allegations are in complete contradiction to both the inner workings of our Senate office and to the man I know and worked so closely with for almost two decades."

Biden's deputy campaign manager Kate Bedingfield also put out a statement disputing the allegation: "Vice President Biden has dedicated his public life to changing the culture and the laws around violence against women. He authored and fought for the passage and reauthorization of the landmark Violence Against Women Act. He firmly believes that women have a right to be heard — and heard respectfully. Such claims should also be diligently reviewed by an independent press. What is clear about this claim: it is untrue. This absolutely did not happen."

Biden himself has not responded to the allegation, a point of particular frustration for Reade.

In the weeks before he launched his candidacy last year, when Biden faced accusations of contact that was said to be unwanted but not sexual in nature, his response to those complaints appeared uneven. The former vice president said he recognized that social norms had changed, and he released a video saying that he would be "more mindful about respecting personal space in the future." But he also joked about having permission to hug people at a union event days later.

Biden's campaign and his surrogates have been careful in denying this new allegation, trying not to personally discredit Reade. Ever since the #MeToo movement erupted, Democrats including Biden have been insisting that society should believe women, but they are grappling with what that means.

When asked about Reade's allegation, some allies have pointed to Biden's legislative record on these issues. Sen. Amy Klobuchar, D-Minn., also a former presidential candidate, told NPR last week, "All women in these cases have the right to be heard and have their claims thoroughly reviewed."

Copyright 2020 NPR. To see more, visit https://www.npr.org.