Here's everything we know about the case.
RELATED: Newest details on the Mollie Tibbetts investigation
When did Mollie Tibbetts go missing?
Tibbetts was last seen going for a run on the evening of July 18. She was reported missing after she did not show up for work and loved ones could not locate her on July 19.
Who was Mollie Tibbetts?
Tibbetts was a 20-year-old sophomore at the University of Iowa. She went to elementary school in the Bay Area but spent most of her adolescence in the small community of Brooklyn, Iowa.
Tibbetts was the middle child of Rob Tibbetts, who lives in California, and Laura Calderwood, who lives in Brooklyn. Mollie has an older brother, Jake, and a younger brother, Scott.
Over summer break she was living with her longtime boyfriend, Dalton Jack, and his brother Blake. She had a job with Unitypoint Grinnell Regional Medical Center working at a day camp, KCRG reports.
Home videos released after her disappearance show a young woman with a playful personality.
RELATED: Home video shows Mollie Tibbetts laughing, dancing
What do we know about the night Mollie Tibbetts was killed?
Both Jack brothers were out of town, so Tibbetts was home alone with the dogs. According to witness accounts and her Fitbit data, she went for a run around 7:30 p.m.
Loved ones have said that authorities told them Tibbetts made it home from her run and was inside on her laptop as late as 10 p.m., though court documents reveal that Rivera remembered "making contact" with a woman who was out running.
Rivera told investigators he "blocked" his memory that night. He said he remembers running alongside Tibbetts and that the next thing he knew he was in his car and there was a woman in his trunk. He said he left Tibbetts, who was bleeding, in a cornfield, according to court documents.
A preliminary autopsy report released Aug. 23 found that Tibbetts died from "multiple sharp force injuries," indicating that she was stabbed.
RELATED: Mollie Tibbetts' disappearance: A timeline
Who is the suspect in the Mollie Tibbetts case?
A charge of first-degree murder has been filed against 24-year-old Cristhian Bahena Rivera, who is also being held on a federal immigration detainer.
Investigators say they used surveillance video in tracking down Rivera. The video showed Tibbetts jogging in a rural area near her hometown of Brooklyn, Iowa, as well as Rivera's car. Investigators said Rivera led them to Tibbetts' body on Aug. 21.
There has been confusion surrounding Rivera's immigration status, with authorities saying he is an undocumented immigrant and his lawyer saying he came here legally as a minor. On Thursday the Iowa Department of Transportation confirmed he does not have any type of state-issued identification.
RELATED: Who is Cristhian Bahena Rivera? What we know about the suspect
It is unknown whether Tibbetts and Rivera knew each other. Tibbetts was friends with Rivera's girlfriend, Iris Monarrez, on Facebook, but investigators said this may have been simply because they went to the same high school, and they were not necessarily personally acquainted.
Where was the body found?
A body which authorities identified as Tibbetts was found in a rural part of Poweshiek County, where Brooklyn is located, AP reports. Local media outlets reported that a medical examiner arrived at a rural area near Guernsey.
What happens next?
If convicted, the maximum penalty for the murder charge is a sentence of life in prison without the possibility of parole. Iowa does not have the death penalty.
Rivera made his first court appearance on Wednesday. He did not enter a plea. His preliminary hearing will be August 31.
Tibbetts' funeral will be held on Sunday, August 26.
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