Des Moines, IA – The farm that employed the illegal alien who was charged with the murder of an Iowa college student said that the man had passed a U.S. government background check.

Dan Lang, of Yarrabee Farms, said 24-year-old Cristhian Rivera had been properly vetted prior to working for his business, ABC News reported.

Rivera was arrested on Tuesday and charged with the first-degree murder of Mollie Tibbetts.

"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," Yarrabee Farms said in a statement late on Tuesday. "On Monday, the authorities visited our farm and talked to our employees. We have cooperated fully with their investigation."

E-Verify is an Internet-based system that compares information from Form I-9 to U.S. Department of Homeland Security (DHS) and Social Security Administration (SSA) records to confirm that an individual is authorized to work in the United States.

According to its website, E-Verify does not provide employers with immigration or citizenship status information. However, an illgeal immigrant should not have authorization to work from within that system.

ABC News reported that U.S. Immigration and Customs Enforcement (ICE) said they did not know how Rivera, an illegal immigrant from Mexico, passed the E-Verify system. He had been in the United States illegally for “between four and seven years,” according to the Department of Homeland Security.

The dairy farm that employed Rivera is owned in part by Craig Lang, a prominent Republican businessman who was the former president of the Iowa Farm Bureau Federation and the Iowa Board of Regents, the Des Moines Register reported. Lang also ran for Secretary of Agriculture in the 2018 Iowa GOP primary and lost.

The farm stood by its hiring practices in their statement released to the media.

“Yarrabee Farms follows all laws related to verifying employees are legal to work in the United States, and we regularly seek outside counsel to ensure we stay up-to-date on employment law matters. We keep records on all employees and have shared that information with authorities,” the statement read.

Tibbetts, 20, was last seen on the evening of July 18 when she went jogging in her hometown of Brooklyn.

Her family contacted the police after she failed to show up at work on July 19, and wasn’t answering her phone.

A massive search effort and a $400,000 reward for information about the missing University of Iowa coed dominated headlines for 34 days, The Washington Post reported.

Iowa Division of Criminal Investigation Special Agent in Charge Rick Rahn announced at a press conference on Tuesday afternoon that a body believed to be Tibbetts had been found on Aug. 21, but said the identity had not yet been confirmed.

The more-than-a-month-long search for the missing woman came to a head a week before Rivera’s arrest, when someone who lived along the route Tibbetts was believed to have been running came forward with surveillance video that showed the young woman jogging by on the night she disappeared, Agent Rahn said.

He said investigators spent more than 100 hours scouring the video and constructing a timeline of the incident.

Through that security footage, investigators were able to identify a black Chevy Malibu that belonged to Rivera, and they were able to determine that he was following Tibbetts. Her “digital footprint” left by her Fitbit and her cell phone also aided police in finding her killer, the agent said.

Agent Rahn said they were able to track Rivera’s vehicle and find Tibbetts running in the video on 385th Street.

He said they brought Rivera in for a lengthy interview on Aug. 20, and he readily admitted that he saw Tibbetts running and said he parked his car and got out so he could run alongside her, the agent told reporters.

Rivera told detectives that Tibbetts grabbed her phone and told him to leave her alone or she’d call the police. He told police that he became angry and chased her down, and then he claimed to have blacked out and didn’t remember what happened, Agent Rahn said.

The illegal immigrant, whom authorities said had been living in rural Poweshiek County, told police that his blackout ended near where they found Tibbett’s body at 460th Street.

Rivera said that when his blackout ended, he saw an earbud in his lap and realized he had put Tibbetts in his trunk, according to an arrest affidavit filed with the Powesheik County Clerk of Courts.

He drove to a cornfield, got out of his car, and went around to the back of the car to pull Tibbetts’ body out of the trunk.

He told police he put Tibbetts over his shoulder and carried her body about 20 meters into the cornfield, where he dropped her and camouflaged her with corn stalks.

Rivera was able to describe what Tibbetts had been wearing and other details specific to the area where the young woman’s body was found, according to The Gazette.

An autopsy will be performed to determine Tibbetts’ exact cause of death, Agent Rahn said.

Rivera was held at the Powesheik County Jail on a $1 million bond. His case will be prosecuted by the Iowa Attorney General’s Area Prosecutors Team, the agent said.

If convicted, the murder charge carries a mandatory life sentence without possibility of parole for Rivera, according to The Gazette.