CHAPEL HILL, N.C. — The University of North Carolina has tried for years to remove the stain of an academic scandal that began with an office administrator setting up sham classes to help struggling students — only to see things get worse. An independent investigator hired by the school outlined how academic fraud ran unchecked for 18 years, rooted in the conduct of a "do-gooder" who handed out artificially high grades in courses that typically required one research paper with no class time in the formerly named African and Afro-American Studies department. Now the school faces renewed questions from its accreditation agency about the university and awaits the NCAA's next move before it can try to repair its damaged reputation.