Authorities said the investigation wasn't related to an exotic dancer's allegations that she was raped and beaten by three men at an off-campus party thrown by Duke's lacrosse team in March.
Police reports show the female student told officers she was assaulted after an annual party celebrating the last day of classes, Julia Lewis of CBS affiliate WRAL reports.
On Wednesday, police searched a male student's dorm for photos, videotapes, cameras, drugs and women's clothing. A search warrant application said they were investigating allegations of second-degree forcible rape, possession of controlled substance and possession of drug paraphernalia.
No charges have been filed, but authorities collected DNA samples from the woman and the man she says attacked her.
The accuser said the man walked her to her room after the April 26 party and had sex without her consent, police said. The man told police he walked the woman to her room and helped her get into bed, but denied raping her.
The man's lawyer, Steve Sitkoff of Los Angeles, said there was "zero truth to the allegations."
"I am confident that once the Duke police, who I have utmost confidence in, have completed their investigation, they will come to the exact same
conclusion I have come to, which is that my client is 100 percent innocent of these allegations," Sitkoff said.
Both drugs and alcohol are believed to have been involved, Lewis reports. Investigators said the woman had consumed a large amount of alcohol at the party and that someone had rigged a vaporizer to spew marijuana smoke into the room.
On a police department website, investigators write the woman could not provide too many details of what happened leading up to the alleged attack, Lewis notes.
Duke spokesman John Burness said he couldn't comment on an ongoing investigation.
Earlier this week, faculty reports called for action to combat alcohol abuse at the university.amid the lacrosse scandal found that Duke's ambivalence toward drinking made it difficult to deal with the issue.