BROOKLYN, Iowa (AP) — For years, the young man from Mexico presented himself as a legal U.S. resident and reliable worker at a family dairy farm in small town Iowa, his employer said.

But this week, the image of Cristhian Bahena Rivera transformed in a matter of hours. Now he's a man accused of illegally living and working in the U.S. on fraudulent documents, of being a predator who kidnapped and killed a beloved young woman, and to some, the monstrous face of a lax immigration system.

Rivera made his initial court appearance Wednesday in a rural Iowa courthouse on a first-degree murder charge in the death of 20-year-old college student Mollie Tibbetts. He sat stone-faced and handcuffed in a striped jail jumpsuit as he said through an interpreter that he understood he faced life in prison if convicted. He was ordered jailed on a $5 million cash-only bond after a prosecutor said he was a danger to the community who was accused of a "heinous crime."

The turn of events stunned the prominent farm family that employed him for the last four years. They said the 24-year-old worked under a different name and was a good employee who helped take care of their cows and got along with co-workers.

Even after Tibbetts disappeared on July 18 while out for an evening run in the small central Iowa town of Brooklyn, Rivera kept coming to work and "nobody saw a difference" in his demeanor, said Dane Lang, the manager of Yarrabee Farms. His colleagues were stunned Tuesday to learn that he was not only the suspect in Tibbetts' death, but that he had a different real name than what he went by on the farm, Lang said.

"Our employee is not who he said he was," Lang said at a news conference at the farm. "This was shocking to us."

When Rivera was hired in 2014, he presented an out-of-state government-issued photo identification and a matching Social Security card, Lang said. That information was run through the Social Security Administration's employment-verification system and checked out, he said.

Rivera's defense attorney, Allan Richards, acknowledged Wednesday that his client received his paycheck under a different name and that he was uncertain of his immigration status. He said he was prepared to argue that his client was in the country legally, noting that he came to the U.S. as a minor and had worked and paid taxes for years.

"He showed up every day and he did his job. He was patted on his back. They turned a blind eye to the reality of documentation," Richards said.

Investigators say they believe Rivera abducted Tibbetts as she went on an evening jog, killed her and dumped her body in a cornfield. A judge on Wednesday agreed to increase Rivera's bond to $5 million from $1 million after prosecutor Scott Brown noted he was a potential flight risk who was charged with a "heinous crime."

His attorney, Richards, lashed out at President Donald Trump for publicly declaring his client guilty at a rally Tuesday night. He said his client was a hard worker with the equivalent of an eighth-grade education, had no prior criminal record and deserved the presumption of innocence and a fair trial.

"Sad and Sorry Trump has weighed in on this matter in national media which will poison the entire possible pool of jury members," Richards wrote in a court filing.

Trump noted the arrest at the rally in West Virginia: "You heard about today with the illegal alien coming in, very sadly, from Mexico and you saw what happened to that incredible, beautiful young woman. Should've never happened. Illegally in our country."

Immigration and Customs Enforcement officials have lodged an immigration detainer for Rivera, a move that means the agency has probable cause to believe he is subject to deportation. No hearing has been held yet on his status.

Yarrabee Farms is a small family farming operation that dates back to 1860 and has been owned for six generations by the Lang family, which is prominent in the community, farming circles and Republican politics. Dane Lang said the farm had received dozens of disturbing phone calls and messages since the employee's arrest, including threats to kill his dog and burn down his buildings.

"This is a scary situation," he said.

His father and farm co-owner Craig Lang, a former president of the Iowa Farm Bureau who ran earlier this year for state agriculture secretary, said the farm was cooperating with investigators and had already turned over Rivera's hiring records. He said now was not the time to debate immigration but to grieve the loss of Tibbetts, who was studying psychology at the University of Iowa.

Rivera led investigators Tuesday to a body believed to be Tibbetts in a cornfield about 12 miles (19 kilometers) southeast of Brooklyn, where she was last seen, police said.

Rivera allegedly confessed to following her and then panicking when she threatened to call police. He told authorities that he blacked out and then dumped her bloody body in the secluded location.

Investigators have not released the cause and manner of Tibbetts' death, and didn't release any information following an autopsy conducted Wednesday.

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.

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. The farm where he worked was just a couple miles away from that location.

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.

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