Officials at the University of North Carolina at Chapel Hill said Thursday  that a continuing inquiry into its football program had uncovered evidence of "possible academic misconduct" by a former undergraduate tutor and an as-yet-undetermined number of players. At a hastily called news conference last night, Chancellor Holden Thorp, clearly troubled by the burgeoning evidence of troubles  in the Tar Heel sports program, said that the extent of the academic wrongdoing remained unclear. But he promised a thorough investigation by a team of faculty members and administrators. "Academic achievement and fairness are at the heart of the University of North Carolina and the Department of Athletics," said Thorp. "We are treating this issue with the seriousness that you would expect. It's a privilege to put on the North Carolina uniform and to represent this University, and it's our job to make sure that the people who do so have earned that privilege."