A woman using the pseudonym "Jane Doe" is suing the University of Wisconsin-Madison chapter of the Sigma Chi fraternity and its national headquarters after she was allegedly drugged and gang raped at a party at the fraternity’s Langdon Street house last October.

Her attorney, Robert Elliot, filed a civil lawsuit in Milwaukee County circuit court last week, alleging that the fraternity’s negligence caused the woman’s injuries and that it failed to create a safe environment. The fraternity’s insurer, Risk Management Foundation, was also named as a defendant in the suit.

A lawsuit tells only one side of a story. Phone and e-mail messages left with the Sigma Chi headquarters and the Risk Management Foundation, both based in Evanston, Ill., were not returned Tuesday.

The Madison Police Department is investigating a reported sexual assault at Sigma Chi’s address, 221 Langdon St., on the same date listed in the lawsuit, said spokesman Joel DeSpain.

He said the alleged victim took a physical exam that is used to collect evidence of sexual assaults on Oct. 5. She reported the incident to police on Oct. 20, he said. He would not comment further on the investigation because he said it is still open.

According to the lawsuit, Jane Doe, who lives in Milwaukee County, attended a party at the fraternity house on Oct. 4, the night of a Badgers football game against Ohio State.

Some time during the night, she was given a drug that knocked her unconscious and was raped multiple times by strangers, who she believes were members of the fraternity, according to the lawsuit. As a result, she has sought health care for physical and emotional pain, the suit says. The woman is seeking punitive damages.

The suit also alleges that Sigma Chi’s national office has failed in the past to supervise the actions of its chapters, going as far back as 1987, citing incidents where fraternity members have been charged with hazing, alcohol abuse, sexual assault, and homophobic and racial hate conduct.

The woman used the name Jane Doe to protect her identity as a victim of sexual assault, the lawsuit states. It’s relatively rare for someone to file a lawsuit under a pseudonym and is up to a judge whether to allow it, said John Barrett, Milwaukee County clerk of circuit court.

In April, the fraternity was suspended from activities involving alcohol as the university investigated an alleged alcohol-related violation unrelated to the sexual assault allegations. The university has also imposed an undisclosed sanction on the fraternity, which is appealing the discipline.