An Iowa judge on Monday denied a request for a new trial by a man convicted in the 2018 killing of Mollie Tibbetts, a University of Iowa student whose body was found in a cornfield weeks after she vanished while going on a run. 

The ruling by Judge Joel Yates clears the way for the Aug. 30 sentencing of Cristhian Bahena Rivera, who was convicted earlier this year of the slaying. Defense attorneys argued that others had committed the murder.

Bahena Rivera, a farmhand living in the United States illegally, was convicted of first-degree murder and faces life in prison. 

MOLLIE TIBBETTS MURDER TRIAL: JURY FINDS CHRISTIAN BAHENA RIVERA GUILTY

In this July 15, 2021, file photo, Cristhian Bahena Rivera appears during a hearing at the Poweshiek County Courthouse in Montezuma, Iowa. Bahena Rivera was convicted of killing University of Iowa student Mollie Tibbetts in 2018. (Jim Slosiarek/The Gazette)

"We are pleased that the judge upheld the jury’s verdict and we look forward to moving to sentencing," said Lynn Hicks, a spokesman for the state attorney general.

Yates wrote that much of the evidence presented was known to them before the guilty verdict was handed down. He said any additional evidence would have to be revealed after the verdict. 

"In reviewing the evidence and testimony provided at trial, the court finds the verdict was not contrary to the weight of the evidence," Yates wrote.

During the hearing, defense lawyers attempted to link Tibbetts' death to a young woman's report of having been kidnapped and sexually assaulted at a home used for sex trafficking and the disappearance of an 11-year-old boy from the same county. 

While being questioned by investigators, Bahena Rivera told detectives that he encountered Tibbetts as she was running in her hometown of Brooklyn, Iowa. He also led them to her body. 

In this September 2016 file photo provided by Kim Calderwood, Mollie Tibbetts poses for a picture during homecoming festivities at BGM High School in her hometown of Brooklyn, Iowa.  (Kim Calderwood via AP, File)

Before his trial, he claimed two masked men kidnapped him at gunpoint and forced him to drive to where Tibbetts was running, killed her, put her body in the trunk of car and made him dispose of it. He said the men threatened to kill his ex-girlfriend and young daughter if he revealed the plot.

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A 50-year-old suspected methamphetamine dealer has been investigated in both cases but hasn’t been charged in either, and prosecutors said he has no ties to Tibbetts.

Prosecutors have said they were confident that Bahena Rivera killed Tibbetts and they pointed out that his own account of what happened didn’t align with what the two new witnesses told police.

The Associated Press contributed to this report.