The University of Wisconsin conducted an investigation last year that cleared former basketball coach Bo Ryan of alleged misuse of school resources during an extramarital affair.
Wisconsin issued a statement to the woman involved in the affair with Ryan on May 13, 2015, concluding that there was "insufficient basis to warrant" any punishment of the longtime basketball coach.
The letter, obtained Saturday by ESPN, said that the school "did not find any evidence where an expense associated with any airfare, hotel room stay, food, drink, or entertainment expenses for you was borne by the University."
The school began its investigation after receiving an email from the woman, university chancellor Rebecca Blank said in a statement also obtained Saturday by ESPN.
Ryan, who retired abruptly in December, acknowledged the affair Saturday in a statement to ESPN's Andy Katz. He said that the affair was "absolutely unrelated" to his retirement.
"My wife Kelly and I believed that the university's findings concluded this matter," Ryan said in the statement. "To be clear, this matter was absolutely unrelated to my retirement many months later. In fact, I timed my retirement intentionally to assure that Greg Gard got his hard-earned opportunity to coach the University of Wisconsin basketball team."
Blank said that Wisconsin received the email from the woman in February 2015. She also said that the school did not influence Ryan's decision to retire on Dec. 15, midway through his 15th season with the Badgers.
"The university determined on May 13, 2015, that Ryan did not utilize university resources during the course of the relationship in question," Blank said in her statement. "The university concluded the issue was a private matter. Bo Ryan's resignation on Dec. 15, 2015, was entirely his decision."
The woman's email to the university, also obtained Saturday by ESPN, was sent to Ryan, Blank and Wisconsin senior athletic department officials Walter Dickey, Terry Gawlik, and Bruce Van De Velde.
The woman said in her email that she accompanied Ryan on "numerous basketball recruiting trips" to locations such as Kansas City, Las Vegas, Chicago and Minneapolis.
In his statement Saturday, Ryan referred to the affair as a "mistake in my private life." He also said that he told the university about the affair.
"I had a relationship with a woman who had no connection to the University of Wisconsin," he said. "That relationship ended nearly 1 ½ years ago. I revealed this issue openly to the university, and encouraged them to review any activity to assure them that no university resources were misused."
Ryan, 68, is the winningest coach in Wisconsin history, with 364 wins over 14-plus seasons. Ryan coached the Badgers to the NCAA tournament every year of his tenure, entering this season. Before Ryan came to Madison, Wisconsin had been to the tournament seven times in school history.
Wisconsin won seven Big Ten titles under Ryan, and his .717 winning percentage (172-68) in conference play is the best in Big Ten history.
The Badgers are 20-10 this season and have gone 12-5 in Big Ten play under Gard, who was named as Ryan's interim replacement. Wisconsin concludes its regular season Sunday at No. 15 Purdue.
ESPN's Andy Katz and The Associated Press contributed to this report.