(CNN) -- A prosecutor announced Thursday that Jameis Winston, quarterback for the No. 1-ranked Florida State University Seminoles, will not be arrested in an investigation into rape allegations last year.
A key factor was the accuser's recollection of the events during the December 2012 incident, in which she alleged Winston raped her after she had been drinking with friends at a Tallahassee bar, said Willie Meggs, the state attorney for the 2nd Judicial Circuit, which includes Leon County and Tallahassee.
"We have a duty as prosecutors to only file ... charges if we have a reasonable likelihood of a conviction," he said. "We did not feel we could meet that burden."
He further said investigators did not have even probable cause to arrest Winston, which requires a low standard of proof.
Defense attorney Tim Jansen described Winston's reaction in a press conference later in the afternoon: "He was very happy. I can tell you he gave me a hug."
In a statement, Winston thanked his family, friends, coaches and teammates for standing by him and Meggs' office for "reaching a decision in a conclusive manner."
"It's been difficult to stay silent through this process, but I never lost faith in the truth and in who I am," Winston's statement said.
Winston, who was at football practice during Jansen's news conference after taking a 1 p.m. exam in school, was confident prosecutors would determine the sexual activity was consensual, especially after two eyewitnesses -- who Jansen said it was a "good bet" were fellow football players -- signed affidavits contradicting the accuser's version of events, the lawyer said.
The two did not participate in the sexual conduct, but "they witnessed parts of the act," Jansen said.
Several people were in the room on the night of the incident, Meggs said, and all were interviewed.
While Winston was satisfied with Thursday's outcome, he was not relieved, Jansen said, "because he knew he didn't do anything. ... We believed it in December. We believed it in February, and we believe it today."
Jansen said he was told the case was closed in February, and he did not know why authorities reopened it in November.
The accuser's family and others claim authorities allowed football interests to dictate the pace and depth of the investigation. Winston is a Heisman Trophy hopeful set to play for a conference championship this weekend, and possibly a national championship thereafter.
Meggs, who attended high school in Tallahassee and has a bachelor's and law degree from FSU, brushed off the insinuation.
"We worked as fast as we could with the time constraints that we have," he said.
Jansen said during his news conference that Winston and his teammates were "preparing right now (for the Atlantic Coast Conference championship against Duke University), and I expect them to perform very well."
As to whether the allegations would affect Winston's chances of Heisman Trophy, given to college football's top player each season, Jansen said, "I hope the voters realize he's never been charged."
While the Tallahassee Police Department's investigation, which the accuser's family has publicly criticized, "could have been handled better," Meggs said, there was nothing that would necessitate an investigation of the department.
Asked specifically about the delay in collecting Winston's DNA, Meggs called it "immaterial" because Winston's DNA matched the DNA on the accuser's underwear. It wasn't a matter of whether Winston and the accuser engaged in sexual activity, Meggs said; it was a matter of whether it was a "forceful act."
Another DNA sample was found on the accuser's shorts, Meggs said, but he wouldn't say who it belonged to.
He did, however, say the accuser "acknowledged having sex with her boyfriend, but she wouldn't tell me who her boyfriend was." Investigators were able to determine his identity later, he said.
Though Jansen had previously said Winston was cooperating with prosecutors, Meggs said Winston didn't talk to prosecutors. Jansen countered Thursday by saying Meggs never requested a statement. Jansen even went to Meggs' office Wednesday asking if there was anything he could do to expedite the investigation, and Meggs told him no, the defense lawyer said.
The accuser's blood-alcohol content when taken, some hours after the incident, was 0.04%, which Meggs said was "not very high." He further said investigators extrapolated the data to determine that her BAC had been about 0.1%, slightly over the legal limit to drive, at the time of the incident.
"We found no evidence of any drugs of any sort in her blood system." he said.
Jansen said later that 0.1% was not a BAC at which someone would forget where they were or what they were doing.
Asked by a reporter if Winston's integrity was in question because he had a girlfriend at the time he engaged in sexual activity with the accuser, Jansen said he wasn't the "moral police."
"I'm sure you all know colleges students may engage in sexual activity," he said.
The attorney took issue with some reporters' characterization of the accuser as a victim in the case, saying, "She is not a victim at this point. She is a complainant, and she is an accuser."
He further said that he had discussed the possibility of civil action with Winston and his family, but he would not elaborate. Nor would he indicate whether it would target the accuser or the media.
The prosecutor's findings, which Meggs said would be available to the media in a report within 24 hours, will demonstrate there was no indication Winston sexually assaulted the woman, the prosecutor said.
"When you see the report, you'll see all the answers," Meggs told reporters.
Among other things, Jansen later said, the report will show that after the incident, the accuser was "perfectly fine, communicating, texting her friends, walking fine."
The Tallahassee Police Department, now that the case is closed, will release details of its investigation, it said in a Thursday statement.
"Those reports document that our department took the case seriously, processed evidence and conducted an investigation based on information available at that time," it said. "The reports also show that, while the victim was unwilling to move forward with charges at that time, all evidence was preserved in the event she was willing to move forward at a later date.
According to police documents, the woman told investigators she had been drinking with friends at a bar called Potbelly's. They later left her after consuming several shots, according to the documents.
She said she did not remember much of what happened next but told investigators she remembered winding up in a ground-floor apartment where a man took off her clothes and had sex with her despite her objections.
The woman came forward a month later to accuse Winston, but Tallahassee's interim Police Chief Tom Coe said last week that she "broke off contact" with investigators in February and said she didn't want to go forward with the case.
The woman's family has said that a detective had warned her attorney that Tallahassee is a "big football town" and that her life could be miserable if she pursued the case.
The case resurfaced after media outlets made public records requests for the initial complaint.
Last month, Winston's attorney announced his client and the woman had consensual sex. The woman's family shot back saying, "To be clear, the victim did not consent. This was rape."
CNN's Michael Pearson contributed to this report.