 -- A report commissioned by the University of North Carolina says school academic advisers steered athletes into sham classes over an 18-year period but does not directly implicate coaches or athletic administrators in the scheme.

The report, released Wednesday, says academic advisers in North Carolina's athletic department colluded with a manager in the African and Afro-American Studies department for student-athletes to take classes to boost their GPAs and keep them eligible in their respective sports.

The classes, in place from 1993 to 2011, were overseen by Debby Crowder, the longtime manager in the African and Afro-American Studies department, and later by the department chairman. They allowed a student to write a paper of at least 10 pages rather than attend lectures or meet with professors. The papers were graded by Crowder, who was not a professor. They typically earned an A or B-plus grade.

The report, the third and most comprehensive produced in the matter, said some academic advisers in the school's Academic Support Program for Student Athletes had ties to Crowder and let her know how high a student's grade needed to be to maintain a 2.0 GPA to be eligible to play. It also said that those advisers pushed Crowder to make exceptions for athletes, including allowing them to enroll in classes after the registration period had ended.

The ASPSA is not part of the athletic department but is located in the same offices. The report says it clearly steered players to the sham classes.

When Crowder retired in 2009, Julius Nyang'oro, the former chairman of the African and Afro-American Studies department, was urged to maintain the program. He was forced to retire in 2012 and was charged with fraud for holding summer classes that didn't exist. Those charges were dropped when he agreed to cooperate with the investigation.

The report, conducted over eight months and including 126 interviews, was led by Kenneth Wainstein, a former federal prosecutor and FBI counsel who now works for a prestigious Washington D.C. law firm. It does not find involvement at the highest levels of the school administration, but it does fault the school for missing a number of red flags.

Wainstein said investigators found a number of academic advisers saw these classes as "GPA boosters."

"Coaches knew there were easy classes," Wainstein said, but added that there was no evidence that coaches or administrators, other than those in APSPA, knew Crowder was grading the course rather than a professor.

School officials said Wednesday that they consider the matter an academic issue as well as an athletic one.

"From the beginning, university has taken the position that these classes started in an academic department by a person employed by academic side of university ... and athletic department took advantage of it," UNC president Thomas W. Ross said.

The report also detailed a 2009 meeting that academic advisers held with the North Carolina football staff. The meeting, which came as Crowder was retiring, included a slide that noted that the classes were "part of the solution in the past" and allowed athletes not to go to class, not to take notes, not to meet with professors and not to engage with the material.

Butch Davis, the UNC football coach at the time, said he did not remember the presentation and said that while he was aware there were classes that were easier, he did not know that the seminar courses were graded by an administrator.

The classes, which no longer exist, were available to all students. Student-athletes accounted for 48 percent of the enrollees in those classes.

The report says Crowder and Nyang'oro told investigators that they believed the UNC administration "wanted them to provide this assistance to the student-athletes." Crowder and Nyang'oro cited the administration's inaction over the years, and Nyang'oro cited comments he received from administrators and faculty suggesting their approval. But the investigators said they found no evidence of that.

"Like everyone who reads it, I feel shocked and disappointed," UNC-Chapel Hill chancellor Carol Folt said in a statement. She blamed what she called "the actions of a small number and inactions of many people" for the problem and said the university had implemented more than 70 improvements to its academic oversight, including personnel changes within the school. Folt would not elaborate on any personnel decisions that have been made.

"When we find people who are accountable, we will take decisive action," she said.

Folt said the school will cooperate with the NCAA, which has not issued any sanctions.

"I can't preempt their investigation or speculate about it," she said.

The NCAA issued a joint statement with UNC later Wednesday:

"The University of North Carolina-Chapel Hill and the NCAA enforcement staff continue to engage in an independent and cooperative effort to review information of possible NCAA rules violations as announced earlier this year. The university provided the enforcement staff with a copy of the Wainstein Report for its consideration. The information included in the Wainstein Report will be reviewed by the university and the enforcement staff under the same standards that are applied in all NCAA infractions cases. Due to rules put in place by the NCAA membership, neither the university nor the enforcement staff will comment on the substance of the report as it relates to possible NCAA rules violations."

Investigators said they talked once to former UNC academic adviser Mary Willingham, who questioned the literacy level of Tar Heels athletes and said UNC had committed academic misconduct before leaving the job in 2010. A report that men's basketball coach Roy Williams told Willingham her only job was to keep his players eligible was not verified; Williams said he didn't believe he had met Willingham, and Willingham, who filed a civil suit against the university in June, did not talk to investigators for a second time to answer that question.

The report listed Wayne Walden -- the associate director of ASPSA and academic counselor for a number of sports, including men's basketball from 2003 to 2009, and who has worked closely with Williams at both Kansas and North Carolina -- as one of the counselors who "steered players into these paper classes." It said Walden and his predecessor, Burgess McSwain, "routinely called Crowder to arrange classes for their players." The report also said Walden later played a role in the basketball players' move away from the paper-class system.

The report said Walden acknowledged knowing about irregular aspects of the paper classes, including that Crowder was doing at least some of the grading. It added that, when asked whether he shared this information with former UNC assistant and then director of basketball operations Joe Holladay or Williams, Walden could not recall doing so.

Both coaches told investigators that they never learned from Walden or anyone else that there was a question about faculty involvement in the classes or that Crowder was doing the grading.

The report said it was unable to corroborate allegations made by former basketball player Rashad McCants to ESPN's "Outside the Lines" that tutors wrote papers for him and his teammates. McCants did not agree to be interviewed for the investigation or offer details to support the claims, the report said.

Seven players who played with McCants told investigators that they drafted their own papers and that tutors' involvement was limited to general suggestions and corrections. They said they took the classes because they were easy but that they did the work themselves.

Information from "Outside The Lines" reporter Steve Delsohn is included in this report.