This police sketch shows a man wanted for questioning in connection to a reported sexual assault that happened on Sept. 27 on University Hill in Boulder. The man is described as a white male in his 20s, about 6 feet, 1 inch tall and 230 pounds. He had dark brown, longer, curly hair and gray eyes and had a scraggly beard. He was wearing a T-shirt, jeans and some kind of closed toe shoes. He smelled of alcohol and a musky cologne.

Boulder and University of Colorado police are investigating reports that three women were sexually assaulted in separate incidents over the past two weeks, including one CU student who said she was raped by a stranger.

Investigations are ongoing, but at this point police do not believe the incidents are related.

Police spokeswoman Sarah Huntley said the first incident was reported by an 18-year-old student at CU, who said she was “very intoxicated” in the early-morning hours of Sept. 27 when she was taken into a house near 11th Street and College Avenue on University Hill and sexually assaulted by a man she didn’t know.

The incident happened between 12:48 a.m. and 1:25 a.m., after the woman left a party at a friend’s house.

The woman told police she had met up with a female friend after the party, but the two were separated briefly when the friend left to give her roommate a copy of their residence-hall room key.

The victim was sitting on a curb at 11th Street and Aurora Avenue, waiting for her friend to return, police said, when she was approached by a man who invited her to come with him.

When she resisted, police said, the man pulled her up and coaxed her into a house in the area. The woman said the man pushed her onto the floor, held her there against her will and sexually assaulted her. Then he let her go, saying, “I’m done. You can go.”

The woman called police after meeting with a victim’s advocate at CU.

While the woman could not recall exactly where the incident happened, Huntley said, she was able to provide a detailed description of the suspect. Police on Wednesday released a composite sketch of the man, who is wanted for questioning.

He is described as a white man in his 20s, about 6-feet, 1-inch tall and weighing 230 pounds. He had dark brown, longer, curly hair and gray eyes and had a scraggly beard. He was wearing a T-shirt, jeans and closed-toe shoes.

“We want to talk with him about what happened that night,” Huntley said. “Based on her allegations, it sounds like the suspect did not know the victim and took advantage of the situation to commit a crime.”

In a separate incident, reported this week, another 18-year-old woman said she was sexually assaulted about 5 a.m. Sept. 28 by an acquaintance she met up with at a party.

Huntley said alcohol was involved in that incident as well, and the woman could not tell officers where the assault happened. The woman lives in Aurora and was visiting Boulder when the alleged encounter took place.

That case remains under investigation, Huntley said.

A third sexual assault was reported to CU police Sept. 29.

CU Cmdr. Brad Wiesley said that assault happened at a Family Housing unit on the CU campus, but the female victim is not a CU student. Detectives have identified people they want to interview in connection to the case, but they have not made any arrests, he said.

Janine D’Anniballe, executive director of Moving to End Sexual Assault in Boulder, said the victims in at least two of the recent cases are part of an all-too-common story.

“Oftentimes, perpetrators pick out people who are most intoxicated or most vulnerable, knowing they’re not going to be able to remember,” she said.

Still, she said, that doesn’t serve as an excuse for victimizing someone.

“Maybe 10 years ago we’d say women should stay together and not get separated from their friends ... but really, that places all the responsibility on the victims and the woman,” D’Anniballe said. “I think we have to ask, ‘Why is it that men and women can both go out, get intoxicated and have fun, but women are the ones at risk of being sexually assaulted?’”

She said her group had a record number of calls to its 24-hour crisis line — 303-443-7300 — during the summer, and that those represented only about 10 percent of the total sexual assaults that took place.

According to Boulder police, so far this year they have received 73 reports of sex offenses, not including indecent exposures. At the same time last year, the number of cases was 65.

Anyone with information about the assaults is asked to call Boulder detectives at 303-441-3330. To remain anonymous, call Boulder County Crime Stoppers at 800-222-8477 or 800-444-3776. Tips can also be submitted via the Crime Stoppers Web site at www.crimeshurt.com.