A county attorney who was asked to look further into the Minnesota DFL Party’s investigative report of a domestic abuse allegation against U.S. Rep. Keith Ellison said Tuesday that he would not do so without an additional review by law enforcement.

Minneapolis City Attorney Susan Segal, who received the report Monday from the DFL, forwarded it to Dakota County Attorney James Backstrom to avoid a conflict of interest given that Ellison’s son serves on the Minneapolis City Council. But in a letter to Segal Tuesday, Backstrom wrote that his office would not look at the report by the Lockridge Grindal Nauen law firm and would only review findings that come from a law enforcement agency.

Backstrom’s letter also disclosed that the law firm requested, in an e-mail to Segal, that the Minneapolis Police Department ­investigate.

Ellison’s former girlfriend, Karen Monahan, alleges that the Democratic candidate for attorney general tried to drag her off a bed during a fight in 2016. He denies it.

“If such an investigation occurs and is submitted to you for review to determine whether or not criminal charges should be filed, I will agree to review the matter on a conflict of interest basis for you,” Backstrom wrote. “However, I will not review any investigation completed by the law firm retained by the Minnesota DFL Party or any other private investigator without the completion of an investigation by a law enforcement agency.”

Segal said Tuesday that her office would not take any further action on the report. She said she chose Dakota County because it prosecutes misdemeanors and gross misdemeanors, and that the allegations didn’t appear to be felonies.

A city official also said Tuesday that Dakota County was ask to review the report to avoid a further perceived conflict in sending the case to a prosecutor from the same party as Ellison. Backstrom is a Republican.

Carla Kjellberg, Ellison’s attorney, said Tuesday, “County Attorney Backstrom rightly determined that law enforcement has no jurisdiction because Ms. Monahan has never made a police report.” An Ellison spokesman earlier referred to a previous statement that Ellison “complied with this investigation fully, and will do so with any other inquiries.” Ellison has also requested a U.S. House Ethics Committee investigation into Monahan’s allegation.

Andrew Parker, an attorney representing Monahan, said Tuesday that Monahan would “welcome any investigation that is fair and impartial, including any law enforcement investigation that is fair and impartial.” He would not comment on whether Monahan would file a complaint alleging criminal activity to Minneapolis police.

A DFL spokeswoman declined to comment on Backstrom’s letter and a Minneapolis police spokesman also declined to comment.

The DFL hired Minneapolis attorney Susan Ellingstad to carry out the investigation. She works at the same firm as the DFL’s attorney Charles Nauen, and Republicans questioned her independence. Doug Wardlow, the Republican candidate for attorney general, spent nearly half his law career working for Parker, who told the Star Tribune that Wardlow was unaware that he has been representing Monahan for about a week.

Ken Martin, the DFL’s chairman, said Monday that the party referred the report to law enforcement after Ellingstad was not able to substantiate the allegation.

In her 15-page report, which the DFL has not released but which the Associated Press obtained, Ellingstad described Monahan as “unwavering in her claim that the alleged physical altercation occurred.” Ellison meanwhile was “credible in his denial” and “truly seemed not to recall the incident ever happening,” Ellingstad wrote.

But Ellingstad wrote that Monahan refused to allow her to privately review an alleged video of the 2016 incident that Monahan has said she recorded on her cellphone. Monahan has offered differing explanations for why she would not release the video.

“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.”