North Carolina fans at a Tar Heels basketball game. Grant Halverson/Getty Images

After a multiyear investigation, the NCAA on Friday announced that it "could not conclude" that the University of North Carolina at Chapel Hill violated academic rules in its fake-classes scandal and that the university would not be sanctioned.

Part of what may have saved UNC from punishment was an argument that certain benefits for student-athletes were also available for students who were not athletes.

The NCAA report said the existence of "paper courses" — which never met and required only one final paper — was widely known around the school.

"The panel cannot conclude that extra benefit violations occurred surrounding the offering or managing of the courses as alleged," the NCAA report said. "The courses were generally available to the student body, and non-student-athletes took the courses.

"Based on the general availability and the lack of specific examples, the panel cannot conclude a systemic effort to impermissibly benefit student-athletes," it said.

The scandal emerged in 2014 with the release of a university-commissioned report led by the investigator Kenneth Wainstein that found widespread enrollment in fake classes at the university. While the public response to the report focused on the school's athletes, the report found that more than half of the students enrolled in the paper courses were nonathletes — many of them referred through the campus' fraternity system.

Wainstein's report found that the paper courses were "hardly a secret" on campus and were predominantly spread by word of mouth among undergraduates.

"As with any course that offers an easy path to a high grade, word of these classes got around," the report said.

One of the largest referrers to these fake courses, which were run by the African and Afro-American studies department, was UNC's fraternity system. The investigators said they spoke with several fraternity members about the courses, and the report described the recollection of two of them:

"Both fraternity members explained that they saw these classes as somewhat of a 'loophole' in Chapel Hill's otherwise demanding curriculum, and they never conceived of these classes as being in any way tailored to athletes. In fact, they recalled that a number of their non-athlete fraternity members took so many AFAM classes that they inadvertently ended up with AFAM minors by the time they graduated."

According to the Wainstein report, "Over the course of ten years, there were 729 enrollments in the paper classes by members of fraternities (and some sorority sisters)."

The report said fraternity members may have had an added incentive to seek out an easy high grade.

At UNC — much as athletes need a minimum GPA to remain eligible to compete — each Greek house needs to achieve a minimum average GPA among its members to maintain university recognition and stay on campus. The report notes that the investigators "understand that the need to meet these requirements played a role in the decision among fraternity members to take these classes."

More than 3,100 students enrolled in the paper courses over an 18-year period.