The man was driving a sport utility vehicle, but investigators said they were not sure if the vehicle was Eve Carson's blue Toyota Highlander, The Raleigh Chronicle reported. The SUV was found Thursday about a mile from where her body had been discovered a day earlier.
Police released the photo to the media Saturday after circulating it Friday among law enforcement agencies, WRAL-TV reported. Investigators said the man was wearing an old Houston Astros baseball cap.
Carson was last seen by her roommates at 1:30 a.m. Wednesday. They reportedly told police she often went to the student government office in the small hours to work.
Her body was found in a quiet residential neighborhood near the campus. Her wallet had not been found Saturday.
Carson, from Athens, Ga., was a popular and academically gifted senior who planned to go to medical school. On Friday, the university board of trustees authorized a $25,000 reward for information leading to her killer.