BROOKLYN, Iowa (AP) — The Latest on the search for a missing Iowa college student (all times local):

11:50 a.m.

The mother of a missing Iowa college student is pleading for anyone who may have abducted her daughter to let her go and claim a fast-growing pot of reward money.

Laura Calderwood said Thursday that she believes her daughter, 20-year-old Mollie Tibbetts, is alive and may have been kidnapped. She said that it's the family's greatest hope that whoever may have Tibbetts lets her go and claims the "money we have raised for her freedom."

Tibbetts hasn't been seen since July 18, when she went for a run in her small hometown of Brooklyn, Iowa. Investigators have reached no conclusions about why she has disappeared.

Calderwood announced at a news conference that $172,000 and counting had been raised for a new "Bring Mollie Tibbetts Home Safe" reward fund. She said the money would be paid to anyone who provides information to Crime Stoppers of Central Iowa that leads to Tibbetts' safety.

Crime Stoppers is promising to protect the anonymity of tipsters.

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10:15 a.m.

Investigators say they have concluded that a woman spotted in northwest Missouri was not a missing Iowa college student.

Iowa Division of Criminal Investigation special agent Mike Krapfl confirmed Thursday that the reported sighting of Mollie Tibbetts wasn't substantiated and has been ruled out by investigators.

Police in Kearney, Missouri, said an employee at a truck stop reported Sunday that she saw someone resembling Tibbetts eating at a Taco Bell. Kearney is about 25 miles (40 kilometers) northeast of Kansas City.

The Kearney Police Department said in a statement that it spoke to witnesses and reviewed video footage before forwarding a report to a task force investigating Tibbetts' disappearance.

Tibbetts, a 20-year-old University of Iowa student, hasn't been seen since July 18 .