The prominent Republican family which owns the farm where Mollie Tibbetts' alleged killer worked have insisted that he passed background checks for migrant workers.

Christhian Rivera, 24, who is from Mexico, was charged with first degree murder on Tuesday after leading police to a corn field where Mollie's body was dumped.

Dane Lang, co-owner of Yarrabee Farms along with Eric Lang, confirmed that Rivera had worked there for four years and was an employee 'of good standing.'

Dane's brother is Craig Lang, former president of the Iowa Farm Bureau Federation and the Iowa Board of Regents, and a 2018 Republican candidate for state secretary of agriculture.

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Cristhian Rivera, 24, was charged on Tuesday after leading police to the corn field where he dumped Mollie's body after attacking her on July 18

It is not yet clear how Mollie (pictured) died. Her autopsy is planned for Wednesday but the results may not be released for weeks

Dane Lang (left) co-owns the farm where Rivera worked with Eric Lang, and said he passed the government's background check for foreign workers. Dane's brother is Craig Lang (right), a prominent Iowa Republican

Craig is the former president of the Iowa Farm Bureau Federation and the Iowa Board of Regents, and a 2018 Republican candidate for state secretary of agriculture

Rivera's employer Yarrabee Farms (pictured) denied hiring illegal immigrants and said the family-run firm would cooperate fully with the Tibbetts inquiry

Dane's statement said: 'First and foremost, our thoughts and prayers are with the family and friends of Mollie Tibbetts.

'This is a profoundly sad day for our community. All of us at Yarrabee Farms are shocked to hear that one of our employees was involved and is charged in this case.

'This individual has worked at our farms for four years, was vetted through the government's E-Verify system, and was an employee in good standing.

'On Monday, the authorities visited our farm and talked to our employees. We have cooperated fully with their investigation.'

The E-Verify site allows employers to establish the eligibility of employees, both US or foreign, by comparing a worker's Employment Eligibility Verification Form I-9 with data held by the government.

The employee is eligible to work in the US if the data matches. If it doesn't, the worker has only eight federal government work days to resolve the issue.

Despite the Lang family using the system, police say Rivera had been in the US illegally for between four and seven years.

Investigators say Rivera followed Mollie in his dark Chevy Malibu as she went for a run around 7.30pm on July 18.

He 'blacked out' and attacked her after she threatened to call the police unless he left her alone, officers said.

Rivera was identified by surveillance footage obtained in the last couple of weeks from someone's home.

It showed him following the student in his car and Mollie running ahead of him. It is not yet clear how Mollie died.

Mollie Tibbetts was abducted on July 18 as she jogged through Brooklyn, Iowa, her hometown

Earlier Monday a member of the Lang family which runs Yarrabee Farms told DailyMail.com he was a personal friend of Mollie and her brothers and was ‘devastated’ by the news of her death.

It’s understood the company hires around 15 migrant workers, most of whom are believed to be Mexican.

Rivera is believed to have lived with a number of other migrant workers on a secluded farmhouse in Brooklyn owned by their employer.

Workers associated with the farm told DailyMail.com that they barely knew Rivera but confirmed that he lived there with a girlfriend named Iris Monarrez and their baby.

They said Iris had gone to stay with her mother after Rivera was arrested in Mollie's murder.

Neighbors told DailyMail.com they had seen a black Chevy Malibu just like the one Rivera was driving when he abducted Mollie regularly driving to and from the property for the past couple of years.

Rivera has been living illegally in Iowa for between four and seven years

Rivera is from Guayabillo in Guerrero, Mexico and was in the United States illegally

Mollie's autopsy is planned for Wednesday but the results may not be released for weeks.

Rivera told police that after seeing her, he pulled over and parked his car to get out and run with her.

Mollie grabbed her phone and threatened to call the police before running off ahead. The suspect said that made him 'panic' and he chased after her.

That's when he 'blacked out.'

He claims he remembers nothing from then until he was back in his car, driving.

He then noticed one of her earphones sitting on his lap and blood in the car then remembered he'd stuffed her in the truck.

Rivera drove her then to a corn field where he hauled her body out of the truck and hid her beneath corn stalks.

He was arrested on Friday after police honed in on his vehicle by viewing surveillance footage obtained from a private resident's home surveillance cameras.

'He followed her and seemed to be drawn to her on that particular day. For whatever reason he chose to abduct her,' Iowa Department of Criminal Investigation special agent Rick Ryan said on Tuesday afternoon.

But it's still unclear what the motive behind the killing was, Rahn said.

Rivera told police he had seen her in the area before. She is friends on Facebook with the mother of his daughter but it is not clear if he and Mollie knew each other.

Mollie was abducted while running along 385th street, in Brooklyn, Iowa, on July 18, and her body was discovered just over a month later in a corn field in Poweshiek County

President Donald Trump chirped in during his Tuesday address at a rally in Charleston, West Virginia, blaming immigration laws for Mollie's death.

'You heard about today with the illegal alien coming in very sadly from Mexico,' he said. 'And you saw what happened to that incredible beautiful young woman.

'Should've never happened, illegally in our country. We've had a huge impact but the laws are so bad. The immigration laws are such a disgrace.

'We are getting them changed but we have to get more Republicans.'

Gov. Kim Reynolds complained about the 'broken' immigration system that allowed a 'predator' to live in her state.

'I spoke with Mollie's family and passed on the heartfelt condolences of a grieving state,' Reynolds said. 'I shared with them my hope that they can find comfort knowing that God does not leave us to suffer alone. Even in our darkest moments, He will comfort and heal our broken hearts.'

At 3pm on Monday, law enforcement arrived at the farmhouse where Rivera worked, according to a neighbor.

FBI agents were still searching the house and a number of nearby trailers on Tuesday afternoon.

Neighbors said the building housed a 'revolving door' of hired migrant workers but that they had never caused any problems.

FBI agents attended another nearby property belonging to the farm overnight Monday to quiz Rivera's co-workers, most of whom claim only to understand Spanish.

'There was a panic when they arrived because they thought at first that it was ICE launching a raid,' a local source told DailyMail.com.

'A lot of these people arrive with forged documents. But it turned it was the FBI and it was about Mollie.'

According to public records the property being searched is owned by Mary and Craig Lang, whose family own the nearby Yarrabee Farms.

Mollie was staying alone overnight in her boyfriend's home the night she went missing and was last seen going for a jog in the neighborhood at around 8pm but what happened afterwards has remained a complete mystery for weeks.

Special Agent Rick Rahn, of the Iowa Department of Criminal Investigation, speaks during a news conference about the investigation of missing University of Iowa student Mollie Tibbetts

Friends and family of missing University of Iowa student Mollie Tibbetts react following a news conference

The family were emotional as they heard that Mollie's body had been discovered

Mollie (left and right) was staying alone overnight in her boyfriend's home the night she went missing and was last seen going for a jog in the neighborhood at around 8pm July 18

Her boyfriend opened a Snapchat photograph from her at 10pm which appeared to suggest that she was indoors but it is not known what time Mollie sent it.

In his arrest warrant, police describe Rivera's chilling confession.

'Rivera admitted to making contact with the female running in Brooklyn and that he pursued her in his vehicle in an area east of Brooklyn. Defendant Rivera stated he parked the vehicle, got out and was running behind her and alongside of her.

'Rivera stated that she grabbed her phone and said: 'I'm gonna call the police.'

He went to get her out of the trunk and noticed blood on the side of her head... he then dragged Tibbetts on foot to a secluded location in a cornfield, put her over his shoulder and took her 20 meters into the field where he left her, covered up in some leaves

'Rivera said he then panicked and he got mad and that he 'blocked' his memory which is what he does when he gets very upset and doens't remember anything after that until he came to at an intersection.

'Rivera stated he then made a u-turn, drove back to an entrance to a field and then drove into a driveway to a cornfield.

'He noticed there was an ear piece from headphones in his lap and that this is how he realized he put her in the trunk.

'He went to get her out of the trunk and he noticed blood on the side of her head.

'He described the female's clothing, what she was wearing including an ear phone or head phone set.

'He described that he dragged Tibbetts on foot from his vehicle to a secluded location in a cornfield.

'He put her over his shoulder and took her about 20 meters into the cornfield and he left her covered in some corn leaves and that he left her there, face up.

'The Defendant was able to use his phone to determine the route he traveled from Brooklyn.

Among his social media photographs are pictures of weapons proudly displayed on a bed. How Mollie died remains a mystery

Rivera is being held on a federal immigration detainer but has also been charged with first degree murder. He remains in custody on a $1million bond

Mollie is Facebook friends with Iris Monarrez who has a baby with her murderer

'Rivera then later guided law enforcement to her location from memory,' the affidavit continues.

Rivera's arrest and the discovery of the student's body brings an end to five weeks of tireless investigation by the FBI, the Iowa Division of Criminal Investigation and local sheriffs.

Rivera's initial court appearance is scheduled for 1pm Wednesday in Montezuma.

If convicted of first-degree murder he faces a mandatory sentence of life in prison without parole.

Last week, the FBI said it believed she had been abducted by someone she knew.

President Donald Trump chirped in during his Tuesday address at a rally in Charleston, West Virginia, blaming immigration laws for Mollie's death.

They warned that the person was 'hiding in plain sight' and had even attended vigils held in her honor but no arrests were made.

A $400,000 fund for her safe return was established but it did not produce any leads either.

Greg Willey of Crime Stoppers of Central Iowa said her family and investigators would dedicate their resources to catching her killer 'once they catch their breath'.

The Iowa Department of Criminal Investigation refused to share details of the discovery on Tuesday when contacted by DailyMail.com.

The only person who had been visibly scrutinized by police after she went missing was pig farmer Wayne Cheney.

He was grilled by officers more than once and had his property searched twice after search crews found a red t-shirt that was similar to one owned by the student near his land.

It was never established if the t-shirt did in fact belong to Mollie.

Mollie's body was found in a cornfield on Tuesday after Rivera led police to it in Poweshiek County

Mollie's boyfriend's older brother Blake Dalton (left with his fiancee) were not in town on the night she vanished either. The only person who has been visibly scrutinized by police is pig farmer Wayne Cheney (right) who was questioned more than once and had his property searched after police found a red t-shirt that was similar to one owned by the student near his land. Cheney took a polygraph test and was never charged. He protested his innocence throughout

Cheney maintained his innocence throughout media interviews and took a polygraph test to try to rule himself out. He was never charged.

In the past few days, Mollie's father Rob Tibbetts, who has been in Iowa since she disappeared, went to California for a 'break'.

Mollie's father Rob went back to California, where he lives, last week for what he called a much needed 'break' from the investigation

He said he had been urged by authorities to do so and that it was a 'half way' point in the investigation.

Rob was not in the state when his daughter disappeared.

Her boyfriend, Dalton Jack, was away for work when she disappeared as was his older brother Blake.

The youngsters lived together in a home in Brooklyn with Blake's fiancee who was also cleared.

As the hunt for her intensified, authorities set up a website that was dedicate to finding her.

It provided a map detailing five locations police considered to be significant. The website also offered a tips page which generated hundreds of clues about what may have happened to her.

The news of her death shook the small town of Brooklyn where most residents are known to each other.

The Rev. Joyce Proctor at Grace United Methodist Church said she'd been praying for Tibbetts' enemies 'to do the right thing... and release her.'

Sadly that never happened.

Proctor, who said she heard Tibbetts 'was a wonderful young lady', said people were in shock their little town isn't as safe as they first believed it was, the Des Moines Register reported.

'I told the ladies at our prayer group this morning that if it's not safe in Brooklyn it's not safe anywhere,' she said. 'And I think that's been a hard thing to realize for a lot of people here.'