Carson was last seen alive at 1:30 a.m. Wednesday, when she stayed home to do schoolwork while her roommates went out, authorities said. But they aren't clear why she was out at 5 a.m., when a report of shots fired was called in to police. Curran said there was no sign of a break-in at her home or any evidence she was having trouble in a relationship that might have led to a conflict.

"As far as I know, she wasn't having any problems with anybody," Curran said.

Curran said police had been in contact with authorities in Alabama investigating the killing of a female student at Auburn University, but added that the cases do not appear to be connected.

Carson was a prestigious Morehead-Cain scholar and a North Carolina Fellow, taking part in a four-year leadership development program for undergraduates. A premed student, she majored in political science and biology, taught science at a Chapel Hill elementary school, studied abroad in Cuba and spent summers volunteering in Ecuador, Egypt and Ghana as part of a school program.

University Chancellor James Moeser has said there is nothing to link Carson's slaying to anyone on campus, where the news of her death has led to a widespread outpouring of grief.

"It's just a huge blow. It's a blow against everything we assume about ourselves, about being a peaceful, safe place where kids come," Moeser said Friday. "She was a joyful person. She loved this place. She loved being here."

Meanwhile Friday, the family of Lauren Burk, the Auburn University student who was found shot and wounded Tuesday night, said they created a fund to help apprehend the killer. Burk was an 18-year-old freshman at the school.

Georgia Gov. Sonny Perdue said he has asked the Georgia Bureau of Investigation to offer assistance in the investigations.