Student Mollie Tibbetts found dead a month after she vanished, authorities say

Mollie Tibbetts, a University of Iowa student who was reported missing. Photos / AP

Days after investigators searching for Iowa college student Mollie Tibbetts said they were focusing their efforts on five locations - a carwash, her boyfriend's home, a truck stop and two farms - the body of the 20-year-old has been found.

Sources close to the investigation told Fox News and CBS News about the discovery, more than a month after Tibbetts went missing, although details were not released.

Authorities have not released information on when or how Tibbetts was found, a cause of death, or whether they have arrested a suspect.

Federal, state and local authorities had scoured Poweshiek County for Tibbetts and sifted through electronic data from her Fitbit, cellphone and social media accounts for any clue about what happened to the woman who was last seen alive while going for an evening run.

The University of Iowa student's last-known communication was a July 18 Snapchat message she sent to her boyfriend, Dalton Jack, for whom she was housesitting, according to the Des Moines Register. Jack, who was out of town, looked at it but didn't immediately reply.

His "good morning" text the next day received no answer, and Tibbetts didn't pick up her phone when someone at the daycare centre where she worked called to ask why she didn't show up. Every call went straight to voice mail.

Assistant Director of DCI Field Operations Mitchell Mortvedt told NBC affiliate WHO-DT that Tibbetts's family members and her boyfriend have been cleared of suspicion.

Her family and dozens of volunteers in the small town of Brooklyn, population nearly 1500, have been combing ditches, cornfields and empty buildings for any sign of Tibbetts. CBS News affiliate KCCI reported that authorities have also searched pig farms in the area, and last week authorities announced they were narrowing the search.

"It's frustrating. It's powerless. We're racking our brains, thinking what can we think of to tell the investigators," Kim Calderwood, Tibbetts's aunt, told the Des Moines Register. "It's the worst thing - to want to fix something you can't fix."

A poster for missing University of Iowa student Mollie Tibbetts hangs in the window of a local business in Brooklyn, Iowa.

Mollie's brother, Jake Tibbetts, told the newspaper the family went "through stages of scared and sad. And now we're anxious and confused."

"Mollie has the biggest heart of anyone we ever knew," he said. "She was never shy. . . . She had room in her heart for everyone."

Tibbetts was born in San Francisco and moved to Brooklyn with her mother when she was in second grade. She won state speech competitions, was involved in theater and ran cross-country. She was studying psychology, as her mother did.

As people searched, those closest to Tibbetts asked everyone to hold on to hope - and keep sharing information about her.

"We remain in awe and indebted to the help, creativity, outreach and love that you have shown Mollie and all of us," Sandi Tibbetts Murphy, a cousin, wrote on the wall of the Finding Mollie Tibbetts Facebook page. "Please keep sharing Mollie's information so we can bring our girl safely home."

A local resident makes his way through the downtown business district in Brooklyn, Iowa.