"I want heads to roll," Patricia Carroll said in an exclusive interview with ABC News.
"The family is proceeding, with civil action against the TPD and Jameis Winston. And possibly the university."
Last month, the Florida state attorney decided not to charge Winston, who had faced felony charges after being accused of sexually assaulting the woman, a Florida State student at the time, at an off-campus apartment on Dec. 7, 2012.
His attorney, Tim Jansen of Tallahassee, said Winston had consensual sex with the woman. But Carroll said Winston raped her 19-year-old client, who withdrew from classes after the allegations resurfaced in media reports.
Those allegations were initially reported to Tallahassee police nearly a year ago, but the investigation wasn't turned over to prosecutors until November.
In the interview with ABC News, Carroll claimed negligence by the TPD, saying the way it handled the allegations led to the prosecutor's decision to drop the investigation.
"Absolutely you're going to see a civil suit," Carroll told ABC News. "You can not have law enforcement that is not held accountable."
Carroll said Thursday that she plans to file a notice to sue the police department early next week. Under Florida law, anyone filing a lawsuit against a government agency must file court paperwork six months prior to the suit itself.
David Northway, a spokesman for the police department, said in a statement Thursday that "based upon the facts and information gathered, no violation of department policy or Florida law was identified on the part of the investigators assigned to this case; therefore no formal internal affairs investigation will be conducted in this matter."
Northway also said: "The reports in this case document that our department took the case seriously, processed evidence and conducted an investigation based on information available at that time. We take seriously the obligation to respond to any individual who wants to report a crime."
FSU and an attorney for Winston couldn't immediately be reached for comment.
Also Thursday, Gov. Rick Scott's office released letters written to him in December by the accuser and her mother, imploring him to reconsider opening an investigation into the case.
Carroll says she asked Florida's attorney general, the Florida Department of Law Enforcement and the governor for an independent examination of the sexual assault investigation, claiming it was riddled with problems.
Scott "didn't even give us the courtesy of a response," Carroll said Thursday.
Carroll sent Scott a letter Dec. 19 -- along with one from the woman and her mother.
The documents were released Thursday by Scott's office following a public records request.
In a one-page letter, the woman who accused Winston told Scott that her attorney received calls from two other FSU students who said they were raped but were "discouraged" from going through with prosecution. Carroll said the family members of those two women contacted her following her December news conference.
The accuser's mother said in her letter that she knows the governor has daughters and asked him to "put yourself in my shoes for a moment."
Her daughter did not "fabricate" a rape, the woman wrote, and did not know Winston prior to Dec. 7, 2012.
"I want to tell you about my daughter with the hopes that you will see her as a real person and not just some name on a police report," the mother wrote, adding that her daughter was heavily involved in school activities and was a leader on sports teams and student government. "I am hoping that this letter makes an impact on your decision and you direct FDLE to open an investigation into the Tallahassee Police Department's handling of this matter. I will not give up on my daughter and will do everything in my power to see that everyone finds out the truth."
Winston won the Heisman Trophy last month and led the Seminoles to the national title earlier this week.
The Associated Press contributed to this report.