LOS ANGELES -- A woman who claims she was raped by Mike Tyson took her accusation public Monday, holding a news conference to denounce prosecutors for failing to charge the former heavyweight champion with a crime.

Arlene Moorman, a 50-year-old grandmother, of Big Bear, Calif., says she was sexually assaulted by Tyson in July at a home he rented while training in the San Bernardino Mountains.

But San Bernardino County prosecutors say there wasn't enough evidence to charge the 35-year-old Tyson.

"I am very distraught and in disbelief that the district attorney's office has decided to forego prosecution in this matter," Moorman said at her attorney's west Los Angeles office. "My suffering has been magnified by their decision."

Moorman's attorney, Gloria Allred, said a civil suit against Tyson is "an option," and complained that the district attorney's office did not sufficiently scrutinize the case.

But Deputy District Attorney David Whitney said the decision not to prosecute was made after a thorough investigation of Moorman's claims.

"We couldn't disagree more with that characterization of the investigation. We are very proud of our investigation," he said. "However, we are not going to discuss the facts of the investigation in the media at this time."

Allred suggested that Tyson got special treatment because of his fame.

"From my discussion with the D.A's office, it appeared to me that the issue for the D.A. was whether it was consensual sex or rape," Allred said. "I believe that this should have been an issue for the jury. In a case where the accused has a previous rape conviction, there should be close scrutiny.

"I'm always very concerned if there is white glove treatment afforded to a celebrity," she said, adding that Tyson "refused to be personally interviewed by law enforcement" during the investigation.

In announcing their decision Friday, prosecutors said that the case was given particularly close scrutiny because of Tyson's reputation for violence and a 1992 rape conviction for which he served three years in prison.

Tyson's attorney, Darrow Soll, issued a statement again proclaiming his client's innocence.

"The facts in regard to this matter are simple -- Mr. Tyson did nothing wrong and both the San Bernardino County district attorney's office and our defense team spent hundreds of hours investigating this matter," Soll said.

"Ms. Moorman can do whatever she wants," he said when asked about the possibility of a lawsuit. "There was a comprehensive investigation and a conclusion that embraced the facts in the case."

Information from The Associated Press and Reuters was used in this report.