THE boyfriend of a university student who disappeared after going for an evening jog last week has revealed she sent him two messages that night — including a mysterious Snapchat selfie.

Investigators said 20-year-old Mollie Tibbetts vanished in Brooklyn, Iowa on July 18. She was last seen going for a jog.

The community of less than 2000 people is located just off the sprawling Interstate 80, nicknamed the Highway of Death for the many unsolved disappearances linked to the route, which bisects the country from New York to San Francisco.

Ms Tibbetts was reportedly staying at her boyfriend Dalton Jack’s home when she went missing. She was there to look after his dogs while he worked at his construction job.

Yesterday, Mr Jack told television station KCRG that he received two messages from Ms Tibbetts on the night she vanished.

He said one was a text message sent at 7pm and the other a Snapchat selfie that appeared to have been taken indoors after she would have returned from her jog. Mr Jack said he opened the Snapchat photo at 10pm, although it is not clear what time it was sent.

A neighbour reported having seen Ms Tibbetts going for a jog earlier in the evening dressed in gym shorts, a black sports bra and running shoes. She was reported missing the following day, Thursday, July 19, after she failed to turn up at work.

“She might have a FitBit on and she might have her cell phone, but obviously we’ve tried just calling her but it’s either off or dead so it would go straight to voicemail,” Mr Jack told ABC News.

Volunteer searches were called off this week as the FBI and state police took over the case, Iowa Division of Criminal Investigation spokesman Mitch Mortvedt told reporters overnight.

“Obviously it’s suspicious and obviously it’s very concerning,” he said. “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.”

Mr Mortvedt said while officials had few leads at this stage of the investigation, they were “leaning more and more toward something happening to her against her will,” including abduction.

Mr Mortvedt said FBI and Iowa investigators were concentrating on areas around Brooklyn that Ms Tibbetts has known to have frequented in the past.

He noted that the town was only around 5km south of Interstate-80 and said authorities were examining footage from highway surveillance cameras and nearby convenience stores.

The FBI is also using an array of computer forensics such as studying online history, social media, mobile phone data and app usage as well as GPS tracking of all her electronic gadgets, including her FitBit.

Agents were working with staff from the University of Iowa, where Ms Tibbetts was taking a degree in psychology, her friends and others to gain access to her laptops and online accounts.

“We’ve issued search warrants to a number of different social media and electronic device type things she was involved in and she used for her exercise routine and were getting some of that information back,” Mr Mortvedt said.

“This could shake out a bunch of different ways. We are hoping and praying for the best outcome.”

Over the weekend, dozens of locals combed fields near both Ms Tibbetts’ house and Mr Dalton’s house, where she was staying. They also blanketed the area with missing posters, T-shirts and billboard pleas.

Mr Jack told TV9 that investigators searched his house after she was reported missing and again on Monday afternoon.

Yesterday, county Sheriff Thomas Kriegel told ABC News that neither Mr Jack nor Ms Tibbetts’ brothers were considered suspects.

The missing woman’s aunt, Kim Calderwood, of Brooklyn, told the Des Moines Registerher family was frustrated by the lack of progress in the search.

“We’re racking our brains, thinking what can we think of to tell the investigators,” she said. “It’s the worst thing — to want to fix something you can’t fix.”