An undocumented immigrant is in custody, charged with first-degree murder in the disappearance of Iowa college student Mollie Tibbetts.

Christhian Rivera, 24, was arrested in Poweshiek County on Tuesday (Aug. 21, 2018). He lives in the rural area where Mollie Tibbetts vanished just over one month ago, Special Agent Rick Rahn with the Iowa Division of Criminal Investigation announced at a 4 PM news conference held in Montezuma. Rahn said that Rivera had been living in the Brooklyn area for four-to-seven years.

Rahn confirmed that a body was recovered in a rural farm field southeast of Brooklyn. He said the identity has not been confirmed, but authorities believe the body is that of the 20-year-old Tibbetts.

The State Medical Examiner is scheduled to perform an autopsy Wednesday. Rahn said it could take anywhere from four to six weeks before officials make a positive identification of the body.

Dozens of law enforcement officials from local, state and federal agencies have been involved in the search for Tibbetts, who last seen jogging near Brooklyn on July 18. The Iowa DCI received more than 4,000 tips during the investigation.

"We regularly had 30 to 40 investigators devoted to this investigation since Mollie disappeared," Rahn said. "Without that kind of support from our fellow law enforcement officers, we could not have made the progress we did."

"Our hearts go out to the Tibbetts family and to the Brooklyn community. It is a loss for all of us," Poweshiek County Sheriff Tom Kriegel said in a statement released to the media at Tuesday's press briefing. "We appreciate the support for law enforcement community in their commitment to this investigation, and we thank the Brooklyn community for their support for the investigation."

Tibbetts would have started her sophomore year at the University of Iowa this week.

This is a developing story. Check back of more information.