Multnomah County District Attorney Michael Schrunk said Wednesday an attorney representing the woman contacted police in late 2006. Schrunk said the woman refused to be interviewed by detectives and didn't want the investigation to continue.
But the woman contacted police in January 2009 and gave a statement, saying Gore tried to have sex with her during a massage appointment at the upscale downtown Hotel Lucia. Gore reportedly was registered at the hotel as "Mr. Stone."
Gore family spokeswoman Kalee Kreider said the former vice president had no comment. Gore and his wife announced June 1 they were separating.
The National Enquirer first reported the allegations Wednesday, identifying the accuser as a 54-year-old woman. Her name has not been released.
A police report prepared in 2007 said the alleged incident happened on Oct. 24, 2006. Gore was in Portland to give a speech on climate change.
According to the report, the woman canceled appointments with detectives on Dec. 21 and 26 of that year. Her attorney canceled another meeting set for Jan. 4, 2007, and said the matter would be handled civilly.
"This case is exceptionally cleared as (the woman) refuses to cooperate with the investigation or even report a crime," the report states.
The case was reopened in January 2009 after the woman contacted police. Detectives interviewed her but determined there was insufficient evidence to support the allegations, Portland police said in a news release.
In a transcript of the interview released by police, the massage therapist said she was doing requested abdominal work on Gore. She claimed he he started to moan, demanded she go lower, and later grabbed her hand and shoved it toward his pubic area.
She alleged he later tried to have sex with her and began caressing her before she squirmed out of his grasp.
The woman said she didn't immediately contact police because she feared "being made into a public spectacle" and having her reputation destroyed.
Detective Mary Wheat, a Portland police spokeswoman, said the woman contacted detectives this month and asked for a copy of her statement. According to Wheat, the woman said she planned to take her case to the media.