Updated: 10/26/10 4:47 p.m.

DEKALB, Ill. (CBS) — DeKalb Police said Tuesday that they believe missing Northern Illinois University student Antinette “Toni” Keller was murdered and her body burned in a park near the school’s campus.

At a news conference Tuesday, DeKalb Police Chief Bill Feithen said for the first time that human remains found in Prairie Park are believed to be Keller’s and that they had been set on fire.

Feithen also said that items they believe were Keller’s were found near the body, leading them to believe the body is Keller’s; but police are waiting forensic analysis to confirm the victim’s identity.

Police have declared the case a “homicide investigation” but have not said how they believe Keller died. Feithen said that the body was too badly burned to conduct an autopsy.

“Due to the state of the burned remains, an autopsy is not viable,” he said, adding that making a positive identification would “take some time.”

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Keller went missing Oct. 14 after telling friends she was going for a walk near West Lincoln Highway by the Junction Center retail complex near the Northern Illinois University campus.

She was a 2010 graduate of Neuqua Valley High School, and was majoring in art at NIU. Keller was active in art and music while she was in high school, Neuqua Valley Principal Bob McBride said.

Authorities have been criticized for disclosing few details about the case since Keller disappeared on Oct. 14, including the fact that the remains were found several days before police announced that information.

Feithen confirmed the remains were actually found Oct. 16: two days after her disappearance and a week before police told Keller’s family or the public.

Feithen acknowledged Tuesday that police waited until Saturday, when the remains were confirmed to be human remains, to announce that the remains had been found at Prairie Park several days before.

“We found the remains early in the investigation,” Feithen said.

Feithen defended the decision to withhold that information from Keller’s family and the public until Saturday. “Had we indicated to the family or to the public that those were human remains or possibly human remains and they turned out to be animal remains … you know, we couldn’t do that.”

But some NIU students say waiting was the wrong decision.

“We were walking around a whole week without knowing there was a murderer,” said a female student.

In an apparent attempt to quell fears that there is a killer on the loose near NIU who might strike again, Feithen said, “Law enforcement has no indication that this is anything other than an isolated incident.”

“Homicides happen and they happen everywhere,” Feithen added. “There could be a homicide in the suburbs tonight.”

Feithen also seemed to be upset at the suggestion that authorities seemed to be trying to avoid saying that a killer is still on the loose.

“Is that not obvious? That … we have human remains, that we have a homicide investigation. We have not announced an arrest. Somewhere there is someone who did this,” “Yes, I’m outraged. You have not walked in my shoes for this last week and a half,” Feithen said.

“I think this community expects their emergency personnel and the people that are responsible for their safety to stay calm, evaluative and focused on the investigation instead of expressing their outrage,” Feithen added. “I have a daughter, I have a son. I have family in this community; I have policemen, families that live all around that park. I had a family member that walked through that park days before. You want outrage? There’s outrage.”

Police have interviewed 50 people during the course of the investigation, but Feithen said that there is “no person of interest in custody at this point.”

School officials have stepped up security on the campus since Keller’s disappearance and restricted access to residence halls. The university is also offering free door-to-door rides to students every day from 4 p.m. to 8 a.m. and is offering security escorts to students, faculty and staff 24 hours a day on campus.

Chicago NIU junior Belisa Richmond got one of those rides. She told CBS 2’s Mike Parker she has stopped walking alone on campus.

“Now I’m taking advantage of using the escorts, as well as the late night services, and they also extended their hours from 4 p.m. to 8 a.m.,” Richmond said, adding that she was “very much” looking over her shoulder frequently.

Keller’s cousin, Mary Tarling, says her family was surprised to learn the remains were discovered so early on.

Police have no suspects, or anyone in custody right now. They’re also asking the public to refrain from using Prairie Park for now.

CBS 2’s Dana Kozlov and Mike Parker contributed to this report.

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