Hairston made headlines earlier this summer when he was arrested on June 5 for misdemeanor marijuana possession and driving without a license. Those charges were later dismissed.
The rental car he was driving during the incident raised questions that remain under investigation by the school.
USA Today first reported that the car was rented in the name of Haydn "Fats" Thomas of Durham. According to the paper, Hairston was also cited for speeding in Durham on May 13 in a car that was rented under the name of Catinia Farrington with the same home address as Thomas.
UNC head coach Roy Williams issued a statement on July 15, saying Hairston will receive "serious consequences," the specifics of which would wait until the school's investigation concludes.
"There are several options available in terms of discipline but we are going to wait until the process is complete to decide on those options," Williams said in that statement two weeks ago.
The rising junior guard announced in April that he would return to UNC for his junior season. He started UNC's final 13 games of 2012-13 at the 4-spot and averaged a team-high 18.2 points per game during that stretch.
ESPN.com projected Hairston as a late first-round draft prior to his decision to return.
The Greensboro, N.C. native led UNC in scoring with 14.6 points per game last season and shot 39.6 percent from 3-point range. His 89 made 3-pointers are the second-most in school history, trailing only Shammond Williams (95 in '96-97). He scored 20 or more points in six of his 14 starts.