The body of Iowa college student Mollie Tibbetts was found 500 yards into a cornfield about 10 to 12 miles south from where police think she was abducted, an investigator tells PEOPLE.
Mitch Mortvedt, assistant director of the Iowa Division of Criminal Investigation, says the Guernsey field was not owned by Yarbee Farms, the dairy farm that employed suspect Christhian Rivera, 24, but that Rivera “was familiar” with the area because he lived and worked a few miles away.
Tibbetts, a 20-year-old psychology major at the University of Iowa, was found buried under parts of cornstalks, says Mortvedt. Her body was 500 yards from a gravel road and not visible from it, he says.
“Corn … in Iowa this time of year is over eight feet tall and has that long skinny leaves as it grows and blossoms, and [Rivera] had ripped off a bunch of those off the corn stalk and just kind of laid them on her to try to camouflage her,” says Mortvedt.
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Although investigators had searched nearby cornfields, Mortvedt says that particular cornfield hadn’t been searched until Rivera allegedly led them to Tibbetts’ body Tuesday.
Authorities have not revealed when, exactly, Tibbetts was killed and Mortvedt would not comment on whether or not Tibbetts was held captive for a period of time. “At this point, we can’t talk about [it],” he says.
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Rivera is charged with first-degree murder in Tibbetts’ death, which preliminary autopsy results show was caused by “multiple sharp force injuries,” although Mortvedt says authorities are not currently providing more specifics.
Rivera has not entered a plea to the charge, but his attorney has said he is presumed innocent, describing his client as a hard worker and “loving father” to his young daughter. At his initial court hearing Wednesday, Rivera’s bond was increased from $1 million to $5 million at the urging of prosecutors.
Tibbetts went missing on July 18 after leaving her home in Brooklyn, Iowa, to go for a jog. Brooklyn is about 11 miles from southeast of Guernsey.
At a press conference Tuesday announcing Rivera’s arrest, Rick Rahn of the Iowa DCI alleged Rivera confessed to circling around Tibbetts a few times with his car before he started running alongside her. Rahn said that Rivera confessed that at one point, Tibbetts told him to leave her alone, threatening to call the police.
Subsequently, Rivera allegedly chased Tibbetts down and at some point said he blacked out, Rahn said.
Rahn said Rivera allegedly admitted seeing Tibbetts previously, but he did not elaborate.
Mortvedt tells PEOPLE that speculation that Rivera and Tibbetts might have known each other prior to her killing “isn’t something law enforcement has verified.”
Rivera had no criminal record before his arrest.
“All of a sudden he just does it,” Mortvedt says. “Who escalates to abduction, kidnapping and homicide that fast?”
“That is part of the ongoing investigation,” Mortvedt says. “We want to dig into his background — and not just the last four weeks. Who is this guy? Where has he been? What has he done? How can we verify that?”