Her father, Rob Tibbetts, said the $172,000 reward is "another tool in our arsenal".
Ms Tibbetts was reported missing the next morning when she didn't show up for work at a day care centre in a nearby town. "It is our greatest hope that if someone has her, that they would just release her and claim that money we have raised for her freedom". Her boyfriend, Dalton Jack, said that if someone took Mollie, he has a message for them. "You would do anything to get her back and you would just be desperate for anything to come forward to get her back", he added.
Investigators have said previously that they were confident on Tibbetts' digital footprint, but they did not release any information as to where that was.
Tibbetts, a 20-year-old from Brooklyn, Iowa, has been missing for two weeks.
Mollie Tibbetts disappeared on July 18 in Brooklyn, Iowa, a small community an hour east of Des Moines, according to the Poweshiek County Sheriff's Office. "There wasn't anybody that she wouldn't bring into her world with love".
"Mollie was a friend to everybody", said Kim Calderwood, her aunt. "I don't know that I have the strength in me, and Mollie's lending me her strength". "We are told very little by the authorities for very good reason", he said, noting how police are hesitant to share information with anyone who could be connected to the case. Her disappearance has gained national attention. Investigators say they have concluded that a woman spotted in northwest Missouri was not Tibbetts.
Tibbetts, a 20-year-old University of Iowa student, hasn't been seen since July 18.
The Iowa Department of Public Safety said that her last known article of clothing is believed to be dark-colored running shorts, and a pink sports top and running shoes, color unknown.
Jack has said that he believes Tibbetts would have had both her fitness tracker and cellphone when she went out for her jog.
"It's one thing to say, 'You know what, call us and we'll protect your identity, won't tell anybody".