Authorities investigating the slaying of the University of North Carolina's student body president Eve Carson are circulating a photo of a possible suspect.

Durham police watch commander Sgt. L.B. Evans said late Friday his department had received a photo of a possible suspect.

Chapel Hill Police Chief Brian Curran said questions about the photo would not be answered until a news conference planned for Saturday and declined to release it.

Police also admitted Friday they needed help in solving the fatal shooting of Carson, issuing an appeal to the public and other authorities with the offer of a $25,000 reward.

Curran said detectives were still focusing on their only concrete evidence to date in the murder of the 22-year-old: her SUV. He believes her killer may have been inside the vehicle at some stage, but reiterated that she appeared to be the victim of a random crime.

"We think she was shot at the location where she was found," Curran said at a Friday news conference he described as his last until there was a break in the case. "There is no suspect at this time."

Because Carson was the well-known president of the student body at UNC-Chapel Hill, detectives were investigating whether she had fallen victim to a stalker.

"She was a high-profile person, so that can't be ruled out," Curran said. There were no signs of sexual assault. Police planned to release 911 tapes from a pair of calls reporting the Wednesday night shooting.

Carson, a senior from Athens, Ga., was found shot to death in the street only hours after she was last seen alive Wednesday.

She was killed by a shot from a handgun to her right temple, according to a police report. There were no marks on her body to suggest a struggle, Curran said Friday.

Her blue 2005 Toyota Highlander was found Thursday about a mile from where her body was discovered, and that was the only evidence Chapel Hill authorities had to go on, according to Curran. He said detectives wanted to talk to anyone who had seen the SUV between 1:30 a.m. Wednesday and midday Thursday.

Officers located the vehicle the after receiving a tip from a witness who spotted it near the main drag though the college town about 45 minutes west of Raleigh.

A $25,000 has been offered to anyone with information leading to the killer or killers, according to Curran.

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The UNC-Chapel Hill senior, of Athens, Ga., was last seen alive at 1:30 a.m. Wednesday, when she stayed home to do schoolwork while her roommates went out, authorities said.

Officers found the body of a young woman about a mile from campus after neighbors reported hearing shots around 5 a.m.

"My information is she was an extraordinarily busy woman and it wasn't unusual for her to go to the office in the middle of the night," Curran said. "But we don't know that's what she was doing."

Police don't know why she was in the upscale residential area where her body was found, he added.

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

"We still don't think there's any connection," said Curran Friday.

Click here to read more about the Auburn University Lauren Burk case.

Earlier, the chief told FOX News that though there were no solid leads, detectives were dogged in their determination to find out who killed Carson.

"We're working as hard as we can, and we're going to keep a positive attitude about solving it," Curran told FOX. "This is a crime that's had a large impact on our community. This has had an effect on all of us."

University of North Carolina Chancellor James Moeser said there was nothing to link Carson's slaying to anyone on campus.

"We have lost someone whom we cherish and love," Moeser told a massive crowd on the school's quad at a memorial service, one of two held Thursday. "We're all in a state of shock."

A huge crowd of students, staff and faculty gathered on campus in the afternoon to remember Carson. Students passed out daisies and carnations, and large boards were erected for students to leave written memories. Dozens of counselors were available to talk to students.

Students met again after nightfall for a candlelight vigil at The Pit, a popular campus gathering spot.

"If they saw a smile on Eve's face, they were smiling," said Carly Swain of Charlotte. "If she was having fun, they had fun for a second because that's the kind of power she had over people."

Moeser said Friday that Carson's death had shaken the entire community.

"This is a place where students really bond to the university and to themselves," he told NBC's "Today." "We can only get through this by embracing each other."

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.

Carson was planning to move to New York City after graduation to do business consulting, according to her friends.

Moeser said he last saw Carson on Tuesday, at the Tar Heels men's basketball game against Florida State.

"This is a tragedy magnified and multiplied by the number and depth of relationships, many relationships that Eve Carson had on this campus," Moeser told the students. "This enormous throng is a testament to the many and deep relationships.

"Eve Carson personified the Carolina spirit."

Click here to watch YouTube video of Eve Carson welcoming students back to campus.

Click here to read Eve Carson's bio and student body election page.

Carson is the daughter of Bob Carson and Teresa Bethke. A man answering the phone at Bob Carson's business, Carson Advisory Inc. in Athens, said the family had no comment.

Maxine Easom, principal of Clarke Central High School in Athens, where Carson graduated as valedictorian in 2004 and was also elected student body president, said she and staff members learned of her death Thursday morning.

"We're devastated," Easom said. "Eve was just the most wonderful young woman you would ever want to know. She was brilliant. She was absolutely beautiful. Everything she did was aimed at helping other people. It's one of the greatest tragedies I've ever known. Eve was one of the young women who could change the world."

The Associated Press contributed to this report.