New details are emerging in the case of missing University of Iowa student Mollie Tibbetts that could help investigators find the reason behind her disappearance, CBS affiliate KCCI-TV reports. Jake Tibbetts, her older brother, said investigators told him evidence from her computer shows she was doing homework on the computer July 18, the night she went missing. But authorities declined to confirm a specific time, citing the active investigation.

Tibbetts, 20, was last seen jogging in her hometown of Brooklyn. She was dog sitting at her boyfriend's home but it is unclear whether she returned after the jog. Her family members believe the new evidence opens up that possibility.

Authorities said her boyfriend Dalton Jack received a Snapchat image from Tibbetts around 10 p.m. and that it appeared to be taken indoors. Her family members and coworkers said she didn't turn up to work the next day.

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Investigators have searched through nearby cornfields and a pig farm near Guernsey to no avail. They've also been using digital forensic searches of her social media accounts, cellphone and fitness tracker in an effort to find her.

Last week, Iowa Division of Criminal Investigation spokesman Mitch Mortvedt said that with each passing day Tibbetts isn't found, the possibility grows that she was taken against her will. But he said investigators "haven't ruled anything out."

Jack was out of town at the time of the disappearance and is not a suspect.

Correction: A previous version of this article misstated the name of Tibbett's boyfriend.