Mollie Tibbetts is still missing after nearly 4 weeks; investigators hope a website will help in the search

(CNN) -- Investigators on Monday rolled out an interactive website to help in the search for a missing Iowa college student who disappeared nearly four weeks ago.

Mollie Tibbetts, 20, was last seen jogging on the evening of July 18 in the small community of Brooklyn, Iowa, an hour east of Des Moines, according to the Poweshiek County Sheriff's Office. Her family said they reported the University of Iowa student missing the next day after she didn't show up for work at a day care.

Authorities are trying to track Tibbetts' digital footprint and have searched ponds, fields, farms, barns, and from the air. No credible sightings have been reported.

The website, findingmollie.iowa.gov, has an interactive map and a link for the public to anonymously provide tips.

"This is just one more avenue for people to take, especially in this digital world that we live in," said Rick Rahn, special agent in charge at the Iowa Division of Criminal Investigation.

Rahn, who declined to reveal details about the investigation, said authorities have received more than 1,500 tips and conducted more than 500 interviews.

Authorities said they are considering all scenarios, including the possibility Tibbetts may have come into contact with someone who caused her harm, but are still treating Tibbetts' disappearance as a missing persons case.

"We haven't lost hope. We continue to strive to bring her back home safely. We are not frustrated," Rahn said. "We just are diligent, and we'll continue to do so."