Mollie Tibbetts Still Missing After Nearly 4 Weeks; Reward Grows To Over $336,000

(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 to help jog the public's memory and a link 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.

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."

The website states:

Although we have not ruled out any scenario that could explain Mollie's disappearance, we must consider the possibility that foul play is involved. Individuals who commit violent crimes often exhibit behavior that is recognized by those with whom he lives, works, attends school, or is in an otherwise close relationship with. Often, someone in the community will unknowingly be associated with the offender, and may be in a position to observe behavioral changes in that person. They will recognize the change and may even question them about it, but will not relate the change to that person's involvement in a crime.

Since Wednesday, July 18, 2018, you may have noticed one or more of the following changes:

• Change in normal routine, which might include missing school, work, or routine engagements without a plausible explanation;

• A vehicle unexpectedly taken to a repair shop or sold/disposed of;

• Unexpected or intensive cleaning of a vehicle, possibly at an unusual time of day;

• Unexplained lack of contact or inability to get in touch with someone you know the evening of July 18th into the morning of July 19th;

• Altering of physical appearance (growth or removal of facial hair, change in cut or color of hair);

• Displays of anxiety, nervousness, stress or irritability;

• Unexplained injuries;

• Changes in consumption of alcohol, drugs or cigarettes;

• Changes in sleep patterns;

• Interest in the status of the investigation, including close attention to media coverage or an unwillingness to discuss the 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. CrimeStoppers of Central Iowa has also raised reward money of more than $336,000 from more than 200 donors, according to Rahn.

(© Copyright 2018 CBS Broadcasting Inc. All Rights Reserved. CNN contributed to this report.)