The reward for the safe return of a missing University of Iowa college student has jumped to $30,000.

KCCI-TV reports that donations are fueling the reward as authorities search for 20-year-old Mollie Tibbetts. A fund for the reward was set up at First State Bank in Brooklyn, Iowa.

Tibbetts was last seen jogging on the evening of July 18 in Brooklyn, a small town Tibbetts had been living this summer. Her family reported her missing the next day after she didn't show up to work.

Dozens of local, state and federal agents are working to determine what happened to the young woman. Investigators said at a news conference Tuesday that they still don't know what happened to her.

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Information from: KCCI-TV, http://www.kcci.com