CHICAGO (CBS)–A first-degree murder charge has been filed against a 24-year-old in the case of Mollie Tibbetts, a 20-year-old University of Iowa student who was missing for five weeks before she was found dead Tuesday morning.

During a press conference Tuesday afternoon, the Iowa Division of Criminal Investigation announced suspect Christian Bahena-Rivera had been charged with Tibbetts’s murder. Authorities confirmed Rivera’s undocumented status.  (UPDATE: On Wednesday Rivera’s lawyer filed court documents arguing the suspect was in the United States legally.)

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He lives in the small rural Iowa farm town where Tibbetts vanished during a late-night solo jog.

Tibbetts’s body was found lying underneath a cluster of corn stalks in a farmfield southeast of the central Iowa town of Brooklyn in rural Poweshiek County

Police said Rivera led investigators to her body after he was seen on surveillance footage in the area where Tibbetts disappeared on July 18.

A black Malibu was seen following her in the footage, police said.

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Police said Rivera admitted to approaching Tibbetts while she was out running. He allegedly said he started running alongside her or behind her. At one point she threatened to call the police and took off running, police said.

He chased her down, and told police he blacked out at the intersection where her body was found.

Police said Rivera has lived in Brooklyn for at least four years.

Mitch Mortvedt, assistant director of the Iowa Division of Criminal Investigation, said authorities were still working to identify the remains.

“This is a small community,” Mortvedt said. “This is sadly a tragic event and we hope it wouldn’t occur anytime in the near future.”

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Note: This story has been updated with the filing of court documents disputing the original claim from investigators that Rivera was in the country illegally. The headline was also changed to remove reference to the suspect’s immigrant status.)