The Lane County District Attorney's Office declined to file charges against the three men, citing insufficient evidence.
The accuser told police that Austin was "the most forceful" of the three alleged attackers. She said she was intoxicated and was pressured into having sex with Austin and two sophomore basketball players, Damyean Dotson and Dominic Artis, after meeting them at an off-campus party hosted by members of the basketball team. She told police they forced her to have sex with them in a bathroom at the party and later at an off-campus apartment.
The woman told police she repeatedly told the men to stop, but they did not until she began to cry.
The accuser said she knew the players' identities because they "called each other by name and they look like they do on the basketball cards they hand out at games. I've seen them on TV, and Brandon is a practice player."
All three men told investigators that they had consensual sex with the accuser.
Dotson and Artis also have been suspended from team activities. All three players were still enrolled at Oregon as of Tuesday.
Austin joined the team in January but did not play after transferring. If he remains at Oregon, Austin will become eligible in December.
The University of Oregon said it had not investigated the allegation, deferring to the authorities. "Law enforcement agencies often request that the university wait to take action in order to avoid interference with an open criminal investigation," the university said in a statement.
Calls to Austin's attorney were not returned.
At Providence, Austin and teammate Rodney Bullock were suspended before their freshman season for a violation of the college's code of conduct. Police in Providence, R.I., conducted an investigation in March after a female student said she was sexually assaulted by Austin and Bullock.
David Lapatin of the Providence police said Tuesday in a telephone interview that the investigation was completed in late March and sent to the Rhode Island Attorney General's Office. The decision on whether to file charges will be up to the attorney general, Lapatin said.
Oregon coach Dana Altman said in January that he talked to Providence's coaches about Austin before the guard joined the Ducks.
"In talking with their coaching staff, we felt like this was something that was not of a serious nature and we'd be able to move on from there," Altman said at the time.