Raleigh, N.C. — Police investigators have interviewed more than 700 people and received more than 1,000 tips in last year's stabbing death of Jenna Nielsen and have made no arrests.

But they are still seeking leads, and they believe the case will be solved, police said Friday.

"I would characterize this case as very solvable," Raleigh police Maj. Rick Grayson said. "We're just missing a couple of pieces. We need the public's help."

Saturday marks a year since the death of the 22-year-old pregnant mother of two who was delivering USA Today newspapers to supplement her growing family's income. She was about a month away from giving birth to her and her husband's third son, Ethen.

Police say she was making a delivery at the AmeriKing Food Mart on Lake Wheeler Road early on the morning of  June 14, 2007, when someone stabbed her in the neck.

Despite national and local media attention in the weeks and months following Nielsen's death and her family's relentless effort to keep the case in the public eye, police have no suspects.

"Every day, something is worked on. It's an unsolved case, obviously, but we're still working hard on it," Grayson said. "Our department has a long history of not giving up."

A detective is assigned full-time to the case, and others are assigned when needed. Investigators also have a dedicated 24-hour hot line (919-227-6220) for the case, and calls still come in on a daily basis, Grayson said.

Police are also renewing their pleas to the public for information about the case, despite how big or small it may be.

"We want people to try to remember what they were doing that day," Grayson said. "It may be something so small that they think, 'Well, the police don't need to know that information.' We need to know everything."

Early in the investigation, police released a composite photo of a person of interest, but have since backed away from the image, concerned it has narrowed the scope of information they've received and may have been misleading, Grayson said.

They now say the person is a short, slightly built man in his late teens or early 20s with black hair pulled back into a long ponytail. He was wearing a dark-colored sleeveless shirt and baggy blue jeans shorts.

His ethnicity is not known, and detectives are urging people to avoid speculation based upon the physical description.

"We want to stay away from that composite as much as we can," Grayson said.

The case received widespread attention in the days and weeks following Nielsen's slaying. Fox News, CNN and America’s Most Wanted featured the case on their programs.

USA Today also published several full-page advertisements about the case, and a local advertising company posted a billboard in downtown Raleigh in an effort to generate leads.

There's also a $15,000 reward for information leading to an arrest and conviction.

Nielsen's father, Kevin Blaine, says the family is still hopeful for an arrest, although it's been difficult.

"I think in the back of your mind, you do, a little bit (lose hope)," Blaine said. "Here we are nearly a year later, and we have nothing."

The family has been very active in its efforts to keep the case alive, posting information about it on a Web site, justice4jenna.org, and fighting for a fetal homicide law in North Carolina that would recognize the death of a fetus as separate crime.

The pain of their loss, however, is still overpowering and doesn't diminish, Nielsen's widower, Tim Nielsen, said.

"Sometimes, you just want to forget about it," he said. "Sometimes, it can be really overwhelming to try to get a peace of mind every now and then. It just overwhelms your thoughts and overwhelms your day-to-day activities. And it doesn't get easier."