DE KALB, Ill. (WBBM/AP) – Officials at Northern Illinois University say the DeKalb County Major Case Squad has assumed lead of the investigation into the disappearance of NIU student Antinette “Toni” Keller.

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Authorities said Thursday the decision to activate the Major Case Squad was made jointly by law enforcement officials from NIU, DeKalb and Sycamore police, the county sheriff and the Illinois State Police.

Keller was a freshman from Plainfield who lived in a residence hall on the NIU campus. She was last seen early afternoon Thursday, Oct. 14, when she reportedly told friends that she was going for a walk in a nature area behind the Junction Center retail complex.

The DeKalb County Sheriff says a dive team has been called in to search the Kishwaukee River for signs of a missing student.

Sheriff Roger Scott says the divers from the St. Charles Fire Department are being used only “as a tool.” He says there is no indication that the 18-year-old Keller of Plainfield might have drowned.

The chief of the DeKalb Fire Department, Bruce Harrison, says the water is “very murky and very muddy” and low. He says a surface search was conducted earlier in the week.

On the campus, students on campus began writing notes of love and encouragement to the family of the missing student.

 “We just said that we’re all there for them and we really, really just want Toni to be found safe,” Ashley DeBartolo, a friend of Keller’s, told CBS 2’s Mike Parker. “She’s one of our best friends, and it’s really hard for everyone.”

 A small group of volunteers called Huskies United met to plan stepped-up distribution of flyers and to make ribbons symbolizing their commitment to Toni.

 “We’re all Huskies here at Northern, and when a Huskey leaves our pack, we need to find her and we need to bring her back,” Jill Thomas said.

It has been a week since Keller disappeared after telling friends at Northern Illinois University she was going for a walk.

Last night, Sheriff Scott says a tip from a motorist led authorities to one area of the county.

“Last night we were particularly involved because there was a report that she might have been sighted out at Route 38, south of Route 38, on Nelson Road, which is out in the county by about 3 or 4 miles. So we had an extensive search last night,” Scott said

He says nothing was found.

“We believe, after talking to the witness, that actually he did see someone on the tracks, though later on he looked at a picture [of Keller] and said it was probably not the same person.”

Authorities say a search volunteer found a shovel south of campus. But it’s not clear whether it has anything to do with the Keller investigation.

NIU says Keller’s dorm key was found off campus – but her father is quoted as saying she lost the key some time ago.

CBS 2’s Mike Parker contributed to this report.

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