A University of Northern Colorado student who says she was raped in December is angry the Weld District Attorney's Office will not file criminal charges against her attacker.

She believes her plight is indicative of the stereotype of rape, especially date rape. She knew the man. She even invited him over, but no means no, regardless of the situation or the misinterpreted signals.

District Attorney Ken Buck told the woman he could not press charges against her attacker, despite the man's admission to police that she said no. Buck said he must only prosecute cases in which he has a reasonable chance of convicting someone, and this was not one of those cases.

"A jury could very well conclude that this is a case of buyer's remorse," Buck said.

The woman, whose name is being withheld because the Tribune does not identify people who allege sexual assault, is 21 and from Colorado Springs.

She says she was drunk Dec. 1 when she called a former lover -- she specified he was not an ex-boyfriend -- to invite him to Greeley.

Although they used to have a sexual relationship, they hadn't spoken in a year. There was a falling-out after she had an abortion, according to him, and after he made a pass at her younger sister, according to her.

Police did not release the man's name because he has not been charged.

The man arrived and had sex with her, while she lost and regained consciousness and repeatedly told him no, she said. She told police she was pretty sure, but not certain, that she said no several times.

The man told police she said no a couple times, but he had thought she wanted to have sex with him. He said she was barely conscious when he finished, and that's when he realized he made a mistake, according to the police report.

"He tried to wake the victim up to get her more conscious so he could apologize," the report says.

In the weeks since she was told there would be no criminal charges, the woman mobilized friends and supporters to ask Buck to file criminal charges; advocates have sent postcards to Buck's office. She contacted sexual assault advocacy groups who have helped spread the word. And she took her story to the media.

Buck said he and other attorneys in his office spent about two hours reviewing the police reports before they decided not to prosecute. Buck then forwarded the case to prosecutors in Boulder County asking for a second opinion, because that community handles more reported sexual assaults.

"I thought, if there's anything they can see in this case that I can't, I want to know about it," Buck said. "They sent back an e-mail saying, 'We agree with your analysis that this case is not prosecutable.' "

Buck said his office prosecutes about 100 sex offense cases a year, which include sexual assaults against children, forcible rape and date rape.

Greeley police filed 46 sexual assault cases in 2005, which include various levels of rape and other sexual assaults.

One in four Colorado women will be victims of attempted or completed rape in their lifetimes, according to the Colorado Coalition Against Sexual Assault, an advocacy group.

"This is not a case that we have a reasonable probability of conviction, but date rape is absolutely a crime and we will absolutely prosecute it," Buck said. "I don't want victims to be deterred from the pitiful facts in this case from coming forward."