When Grace Rebecca Mann, a popular junior and outspoken feminist at the University of Mary Washington in Virginia, was killed in April, her death was treated as not only a tragedy but a mystery. The police quickly apprehended a suspect, Ms. Mann’s housemate, but her friends and family were at a loss to explain the motive.

Still, for months before Ms. Mann died, she and her friends feared for their safety and told the university so. In a complaint to be filed Thursday with the Department of Education, which investigates schools for mishandling sexual harassment and sexual assault cases, a feminist student group that included Ms. Mann says the university failed to protect them from a “sexually hostile environment” in which they were verbally harassed in person and threatened on Yik Yak, an anonymous social app that has been criticized as a permissive platform for racism, sexism and violence.

The complaint does not allege that the university is responsible for Ms. Mann’s death, which occurred off campus in a home she shared with three people in Fredericksburg, Va. One of them, Steven Vander Briel, is charged with first-degree murder in her strangulation. Investigators have not speculated on a motive.

“What we are alleging,” said Debra S. Katz, a lawyer for the students, “is that she and the other women were being threatened routinely, that they lived in a state of fear, there was a culture that was allowed to exist at the university and that this is a tragic loss, and we believe this is something that should be looked at as a potential hate crime.”