The hundreds of interviews refer to tips that investigators have received, said Richard Rahn, Special Representative of the Iowa Criminal Police. The sheriff's office is due to update the investigation on Tuesday.
"People are worried and want to help," said Rahn. "We welcome the phone calls and do everything."
Investigators will continue to analyze data, go through the Leads list and have agents on-site to locate Tibbetts. The data includes social media and information from a Fitbit that Tibbetts is aware of
"We live in a digital world," Rahn told the CNN sister network HLN. "We're going to look at cell phones, computers, social media sites, and everyone knows there's a Fitbit involved too, so we'll look at it and try to make a schedule as good as we can we have done so far. "
Investigators ran search orders for Tibbetts Fitbit, which carried them, and their Snapchat, Instagram and Facebook accounts last week, said Mitch Mortvedt, spokesman for the Iowa Division of Criminal Investigation.
On July 1
"Mollie is a very, very responsible person and she is super nice and compassionate and just someone to look up to," said Hope Beck, her best friend, to HLN. "She strives to be like her, and it's just not likely that she would run away, she had career plans, she planned a vacation, it's just not that she does not spend a while with her friends or her family
He became worried and knew that something was wrong when she was not doing her job.
"She did not call," he told the station. "I looked at my phone and noticed that I wrote them a good morning that morning and they did not look at it, so I hugged their friends and family."
"We've done everything we've been able to investigate, hoping to locate Mollie, and we'll continue to do that until we find her," Rahn told HLN.
CNN's Artemis Moshtaghian, Chris Boyette and Elizabeth Choi contributed to the report.