FAIRFIELD — Police investigating a sexual assault reported by the St. Vincent’s Medical Center emergency department early Sunday morning have been stymied by the victim, a student at Fairfield University.

The alleged victim, a 20-year-old from Mineola, N.Y., told police she and her roommates were hosting a party at the campus townhouses. She said at one point she went upstairs to fix her hair when there was a knock on her door. She let in a man she said was a friend of one of her roommates.

She said the two had non-consensual sex, but refused to provide police with her assailant’s name. According to police, she said she did not want him arrested, and that she had gone to the hospital “to be tested.”

Fairfield University was informed of the incident and the Detective Bureau is continuing its investigation.