(CNN) A preliminary report from the autopsy on Mollie Tibbetts' body determined that her death was a "homicide resulting from multiple sharp force injuries," the Iowa State Medical Examiner said.

Tibbetts, a 20-year-old student at the University of Iowa, went missing after an evening jog on July 18, sparking an extensive month-long search in the region. A body that officials believed to be hers was found on Tuesday in a rural area, hidden under corn stalks, and the autopsy confirmed her identity.

"Sharp force injuries" are those caused by pointed or sharp-edged objects, such as in stab wounds, incised wounds and chop wounds, according to the medical news site Medscape

Tibbetts' funeral has been scheduled for Sunday afternoon, according to a release on the Smith Funeral Home and Cremation Service website. The Mass of Resurrection will be held at the gymnasium of the BGM High School in Brooklyn, Iowa.

Cristhian Bahena Rivera, a 24-year-old Mexican man who illegally came to the United States, was charged with her murder on Wednesday after he confessed to following her on her run. In an arrest affidavit, Rivera said he remembered getting mad at her; what happened afterward was "blocked" from his memory.

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