An attorney hired by Minnesota Democrats to investigate a domestic abuse allegation against Rep. Keith Ellison said she could not substantiate that claim because the lawmaker’s ex-girlfriend has declined to turn over a video she says she has of the incident.

Susan Ellingstad, the lawyer hired by Minnesota’s Democratic-Farmer-Labor Party, said in a draft report obtained by the Associated Press that she was not able to obtain evidence of the claim from the ex-girlfriend, Karen Monahan.

Monahan alleged that Ellison dragged her off a bed by her feet while yelling at her in 2016. Ellison, the deputy chairman of the Democratic National Committee who is running for state attorney general, has denied he was abusive toward her.

Monahan told Minnesota Public Radio last month that she would not be releasing the video because the alleged incident was traumatizing and humiliating. It also set a standard that abuse survivors must prove their stories, she said.

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Ellingstad, who has ties to the DFL Party, noted in her draft report that Monahan would not let her view the video privately and had changing explanations for why she would not turn over the footage. Some of the explanations she gave, according to the Associated Press, was that it was lost, it was on a USB drive in storage, and that it would be too traumatic for her to release.

"An allegation standing alone is not necessarily sufficient to conclude that conduct occurred, particularly where the accusing party declines to produce supporting evidence that she herself asserts exists," Ellingstad wrote. "She has thus repeatedly placed the existence of the video front and center to her allegations, but then has refused to disclose it."

Ellison thanked Ellingstad for a “thorough, independent and fair review,” despite the report not being released publicly.

"Addressing this allegation has been especially challenging given the important national moment we are in," he said in a statement. "I believe women who come forward must be heard, and to have their allegations fully investigated. This is why I have complied with this investigation fully, and will do so with any other inquiries."

DFL Party Chairman Ken Martin said Monday that the report had been released “without our knowledge by someone outside of our organization” and that the findings in their investigation would be handed over to law enforcement.

“We understand the public's desire for definitive answers in this matter, but absent substantiated evidence that proves the claim or definitive exculpatory evidence, we believe it is prudent to ask law enforcement authorities to review the information as a final step in this process,” Martin said in a statement.