The death of an Iowa college student who had been missing for one month before her body was found in a cornfield earlier this week has been ruled a homicide.
According to the Iowa State Medical Examiner, Mollie Tibbetts' death resulted from "multiple sharp force injuries," though "further examination may result in additional findings."
Tibbetts' July 18 disappearance while out jogging set off a massive search that went on for weeks before coming to a tragic end.
Rivera led investigators early Tuesday to a body believed to be Tibbetts in a cornfield about 12 miles (19 kilometers) southeast of Brooklyn, Iowa, where she was last seen going for an evening run, Iowa Division of Criminal Investigation special agent Rick Rahn said.
"I can't speak about the motive. I can just tell you that it seemed that he followed her, seemed to be drawn to her on that particular day, for whatever reason he chose to abduct her," Rahn told reporters.
Investigators said they zeroed in on Rivera after obtaining footage from surveillance cameras in Brooklyn. The footage showed a Chevy Malibu connected to Rivera that was driving back and forth as Tibbetts was running in the area, Rahn said.
An affidavit attached to the criminal complaint against Rivera alleged that he admitted to investigators he got out of his car and started running alongside Tibbetts.
Tibbetts grabbed her phone and said she was going to call the police. The affidavit said Rivera panicked and then said he blacked out. Rivera next remembers seeing her earphones on his lap, and taking her bloody body out of the trunk of his car, it said.
Rivera was cooperating with investigators and speaking with the help of a translator, Rahn said.
A conviction on first-degree murder carries a mandatory sentence of life in prison without parole in Iowa, which does not have the death penalty.
Tibbetts would have started her junior year at the University of Iowa, where she was a psychology major.
Her family released a statement Wednesday thanking people from around the world for the "outpouring of love and support that has been shared in Mollie's name."
The statement added, "We know that many of you will join us as we continue to carry Mollie in our hearts forever."
- Read the full family statement here.
U.S. Immigration and Customs Enforcement said it lodged a federal immigration detainer for Rivera after he was arrested on the murder charge. That move means the agency has probable cause to believe he is subject to deportation.
Investigators said they believed Rivera had lived in the area from four to seven years.
Rivera's attorney challenged the government's statement that the suspect has been living in the United States illegally.
In a court document, defense attorney Allan M. Richards stated that an employer has said Rivera has legal permission to be in the U.S. The document named Craig Lang, a former head of the Iowa Board of Regents, which oversees the state's three public universities. Lang is co-owner of a dairy that employed Rivera.
Rivera's immigration status was confirmed by an E-Verify electronic immigration status check, the Lang family said in a statement.
Richards sought a gag order and said comments about the case by President Donald Trump would "poison the entire possible pool of jury members."
He also asked that the proceedings be closed.
"The government has weighed in at the highest levels with a predisposition that my client is guilty," he said.
Trump seized on the man's arrest on Tuesday to call the nation's immigration laws "a disgrace" that will only be fixed by electing more Republicans. Iowa's Republican governor, facing a tough re-election challenge in November, blasted an immigration system that "allowed a predator like this to live in our community." And Iowa's two GOP U.S. senators called the death a tragedy that "could have been prevented."
In a statement late Tuesday, Yarrabee Farms said Rivera had worked at its farms for the last four years and was an employee in good standing. The Brooklyn-based company said it was shocked to hear that Rivera was charged in Tibbetts' death. Ywa Farm Bureau.
A search of Iowa court records revealed no prior criminal history, and it's unclear whether he had ever been subject to prior deportation proceedings.
Rivera's Facebook page described him as being from Guayabillo, a community of less than 500 people in the Mexican state of Guerrero. It's about a three-hour drive from the resort city of Acapulco.