"Obviously it's suspicious," says Mitch Mortvedt, a spokesman for the Iowa Division of Criminal Investigation, of Tibbetts' case

By Chris Harris
July 25, 2018 01:48 PM

The FBI has now joined the search for missing university student Mollie Tibbetts, in eastern Iowa, as state authorities tell PEOPLE it appears increasingly likely the 20-year-old vanished under sinister circumstances.

“Obviously it’s suspicious and obviously it’s very concerning,” says Mitch Mortvedt, a spokesman for the Iowa Division of Criminal Investigation, who is speaking on behalf of state and federal investigators. “She’s a college student who is very well-connected and involved with social media. For her to stop all types of contact — it’s suspicious.”

“We’ve found nothing that sends us one way of the other,” Mortvedt explains to PEOPLE, “but common sense would dictate that the longer this goes on, the more it is leaning toward something happening to her against her will.”

Police and volunteers have been looking for any sign of Tibbetts since last Thursday, when her parents reported her missing from Brooklyn, Iowa, where she lives.

The last time she was seen alive was a week ago, when someone spotted her on her regular evening jog in Brooklyn, Iowa, where she lives.

She also sent a text message that night, around 7 p.m., and her boyfriend, Dalton Jack, opened a Snapchat message from her about 10 p.m., though it’s unclear when she sent it.

The message was a selfie that appeared to have been taken indoors, Jack has reportedly said. He said he last saw Tibbetts on July 16 before traveling some two hours away for a construction job.

Tibbetts is described as 5-foot-3-inches tall, weighing about 120 lbs., with long brown hair and brown eyes.

The rising sophomore at the University of Iowa, described by friends as sweet and sunny, was staying at her boyfriend’s house and dog-sitting for him at the time of her disappearance.

Mollie Tibbetts
Mollie Tibbetts
Poweshiek County Sheriff's Office

From the beginning, detectives have been handling the case as they would any major crime, in the event it takes that turn.

Because “Mollie was a creature of habit” and used the same three routes for her run, Mortvedt says the volunteer search for evidence into her disappearance — which has been fruitless so far — has been called off.

“We have retraced her steps and have eyewitnesses who saw her out running,” Mortvedt says. “We have 40 to 50 law enforcement personnel researching a lot of the same areas, looking for evidence, and examining — if this was an abduction — points of travel in and out of town.”

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Mortvedt notes that Interstate 80, which stretches from San Francisco in the west to Teaneck, New Jersey, in the east, “is four miles south” of Brooklyn.

“We are looking at convenience store videos in town and surveillance footage captured along the interstate, and we have been interviewing and re-interviewing people,” he says.

Mollie Tibbetts

Investigators are also poring over the data recovered from Tibbetts’ social media accounts and her fitness tracker.

“We believe she was wearing it because she was known to wear it all the time, and we are starting to get lots of information back from the company,” Mortvedt says.

He tells PEOPLE that local, state and federal authorities have been pooling their resources and working closely to locate Tibbetts: “We’re hoping to bring Mollie home.”

Anyone with information about her whereabouts is urged to email investigators at tips@poweshiekcosheriff.com or call 641-623-5679.