(CNN) -- A whistle-blower whose research on athletes' literacy caused a firestorm of controversy at the University of North Carolina is leaving, she told CNN on Monday.
Mary Willingham said it's her choice. She said she hasn't yet turned in a final letter of resignation but simply informed her boss that she plans to leave before the end of the semester.
"It's been a hostile work environment the entire year," Willingham told CNN. "I stuck it out because I wanted to make good on promises to my students, but it has not been fun."
UNC spokesman Joel Curran said he was aware of Willingham's public comments, but he was "unaware as to whether or not she has formally tendered her resignation."
Willingham was one of the original UNC staff members to publicly call attention to a system of "paper classes" at UNC. She told the The News & Observer newspaper in nearby Raleigh that athletes were pushed into classes that required very little work and no attendance.
This year, she told CNN that during the course of her research, she personally worked with athletes who were functionally illiterate. Her research was disavowed by the university.
UNC said three independent experts in adult literacy conducted a university-commissioned review of Willingham's research and found flaws in her claims that some athletes were reading at elementary-school levels.
Willingham's research, described to CNN in January, was based on a sampling of about 180 athletes with whom Willingham worked during an eight-year period.
Each had taken a 25-question reading vocabulary test on the Scholastic Abilities Test for Adults. The aptitude test used by many universities to gauge the learning level of incoming students.
Last month, a Washington whistle-blower group wrote a letter to UNC, demanding the university apologize to Willingham and launch an investigation into the way it says she has been publicly smeared, most specifically by Provost Jim Dean. The group said it was possible that North Carolina whistle-blower laws were broken.
Since the CNN report aired, UNC has asked for a new investigation into the yearslong paper class scandal, in which student-athletes allegedly were taking classes in which the only requirement was completing a single paper.
Attorney Kenneth Wainstein, who had worked at the U.S. Justice Department for 19 years, is reviewing whether it was widely known among staff in athletics that players were sent to no-show classes where little or no work was required.
U.S. Rep. Tony Cardenas, D-California, is also demanding the NCAA address why UNC was never sanctioned.
Willingham told CNN that the paper classes were widely known and talked about in athletics, where she worked for seven years. She also said the paper classes were used to keep eligible some of the athletes who were reading at low levels.