Defense attorneys for the undocumented immigrant convicted of murdering Mollie Tibbetts argued Tuesday that their client deserves a new trial, citing evidence they said ties her abduction and stabbing death to another man. 

The lead investigator into the 2018 death of the University of Iowa student expressed confidence that Cristhian Bahena Rivera killed Tibbetts during hours of testimony in which defense lawyers tried to link the death to a report by a woman who claimed she was kidnapped and sexually assaulted and the disappearance of an 11-year-old boy in the same county. 

Division of Criminal Investigation agent Trent Vileta said that had they known, detectives searching for Tibbetts in 2018 would have looked into another woman’s claim that she’d been lured by a man from Tibbetts’ small hometown of Brooklyn, Iowa, weeks earlier and held in a nearby home for sex trafficking.

The complaint did not lead to criminal charges and Vileta said the evidence in Tibbetts' death pointed to Bahena Rivera, a local farmhand. Bahena Rivera partially confessed to stalking Tibbetts while she was out for a run, killing her and dumping her body in a cornfield. He led investigators to the location following an interrogation in August 2018. 

MOLLIE TIBBETTS MURDER TRIAL: JURY FINDS CHRISTIAN BAHENA RIVERA GUILTY

"Cristhian Rivera murdered Mollie Tibbetts," Vileta testified.

A 50-year-old suspected methamphetamine dealer has been investigated in the case regarding the woman and young boy but hasn't been charged in either, and prosecutors said he has no ties to Tibbetts at all.

During hours of testimony, prosecutors repeatedly objected to the line of questioning by the defense, saying there was no relevance. Yates told Bahena Rivera’s lawyers at times that he was having trouble seeing any relevance to the case against their client.

Bahena Rivera, who illegally entered the U.S. from Mexico as a teenager, was convicted of Tibbetts death following a two-week trial in May. He claimed two masked men kidnapped him at gunpoint and forced him to drive where Tibbetts was running on a rural road. He said they killed her and put her body in the trunk of his car and made him dispose of her. 

He didn't tell investigators about the men earlier in the inquiry because they threatened to kill his girlfriend and young daughter, he said. 

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, Pool, File)

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, Pool, File)

At the end of his trial, two new witnesses came forward independently of one another and told police that a local 21-year-old man, Gavin Jones, told them he had killed Tibbetts. Defense lawyers requested a new trial based on that and other newly discovered information, and Yates agreed to postpone Bahena Rivera's sentencing while he considered their request.

One of those witnesses, an inmate named Arne Maki, testified Tuesday that Jones told him of his involvement last year when they were both held at the Keokuk County Jail. Jones said he and another man stabbed Tibbetts after she was held at a sex trafficking "trap house" where they were staying and framed Bahena Rivera for the death, Maki testified. 

An older man in charge of the house had ordered her killed, Maki said.

Mollie Tibbetts poses for a picture during homecoming festivities at BGM High School in her hometown of Brooklyn, Iowa. (Kim Calderwood via AP, File)

Mollie Tibbetts poses for a picture during homecoming festivities at BGM High School in her hometown of Brooklyn, Iowa. (Kim Calderwood via AP, File)

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"I just want to say one thing, my thoughts and prayers go out to the Tibbetts family," Maki said, after his testimony concluded.

Jones has denied being involved in Tibbetts' death. 

At the end of the hearing, Yates said he would issue a written ruling as soon as possible. 

The Associated Press contributed to this report.