The filing said she met Anderson when the two were at a bar on November 16 and his friends insisted Anderson drive her home.
Per George Schroeder of USA Today, Cleveland County district attorney Greg Mashburn announced the decision on Thursday.
One friend told police that Thornton called Anderson a "nice guy" for not going all the way with her that night.
During a news conference, investigators with the district attorney's office say that information provided to them by the Norman Police Department made them believe that no charges were warranted.
Mashburn said there's not evidence the accuser communicated "no" to Anderson.
The woman also told police in her second statement that she and Anderson exchanged phone numbers when he left her place.
Anderson, who is OU's leading rusher ahead of the Sooners' game against Georgia in the January 1 Rose Bowl, denies the claim against him.
Thornton called the friend from the bathroom of her apartment, excited that Anderson was at her home, saying she "had vomited but meant to brush her teeth and go back and kiss him some more", Caswell said.
Previous reports indicated that charges were unlikely in the case, due in part to text messages from the accuser to Anderson after the night of the alleged incident. She said the accuser was very excited Anderson was at her house, and while she sounded tipsy she did not sound drunk.
Police had described Anderson as a rape by instrumentation suspect because the woman claimed the rape involved his fingers. But, on the weekend of December 2, she said she started talking to her friends and remembered that Anderson forced himself on her.
Anderson's attorneys noted that the running back passed a polygraph test last week denying the accusation. Anderson is the leading rushing for the Sooners this year and is a threat in both the running and passing attack of Oklahoma. Mashburn said no charges will be filed against the accuser and that there was no "malicious intent" on her part.
In an era when accusations of sexual misconduct are ending careers every week, a false rape accusation against a high-profile college football player in Oklahoma is an example of a woman attempting to use benefit of the doubt to ruin a man's life.