BROOKLYN, Iowa (AP) — The reward fund offered for the safe return of a missing University of Iowa student has grown to nearly $316,000.

A spokesman for Crime Stoppers of Central Iowa said Thursday the organization has passed on more than 830 tips to authorities investigating the disappearance of Mollie Tibbetts.

Tibbetts' father has suggested she might have been abducted from her boyfriend Dalton Jack's home in Brooklyn, Iowa. The 20-year-old Tibbetts was seen jogging July 18 and her family reported her missing the next day.

Jack's brother, Blake, told Fox News there were no signs of struggle at the home, adding that Tibbetts is "small, but she would have done something" if she had been attacked.

Dalton Jack says he received a Snapchat message from Tibbetts July 18, after she would have returned from her run. Authorities haven't found her Fitbit or cellphone.