The verdict comes nearly three years after the body of the 20-year-old woman was found in an Iowa cornfield.
The jury of five women and seven men deliberated about three hours on Thursday and about fours hours on Friday, according to a pool report.
Rivera then led police to the cornfield, where investigators found her body with fatal stab wounds, prosecutors said.
After the verdict, prosecutor Scott Brown said the Tibbetts family was “relieved” and “pleased” with the decision.
“The family, and other people that are that close to it, they live with it forever,” Brown said of the tragedy. “We hope that in the end … when these cases are over, we can bring a sense of justice to them, even though we would never have the ability to bring Mollie back.”
Defense attorney Chad Frese said outside court that he planned to appeal.
Frese said Rivera’s admission to having Tibbett’s body in his car, the DNA evidence in the trunk and his leading police to the body made it a difficult case to defend.
“Can we tell you who did this? No,” Frese said. “We can tell you that getting to know Cristhian Bahena we are very surprised that he would be the kind of person to commit a crime like this. He is nothing but a soft-spoken, respectful, kind person.”
In testimony Wednesday, Rivera — speaking through an interpreter — told a very different story. He said two masked mystery men kidnapped him, forced him to participate in their plot to kill Tibbetts, threatened his family and told him to remain silent.
In closing arguments, Brown dismissed that testimony and said it did not fit with the evidence.
“There weren’t two other guys. That’s a figment of his imagination,” Brown told jurors. “All of the credible evidence in this case points at him.”
Frese said the prosecution had no murder weapon, no crime scene, no eyewitnesses, no confession, no motive and no scientific evidence to prove his client’s guilt. He said Rivera’s original statements to investigators were made under duress during an 11-hour interrogation.
“We think Cristhian’s ‘confession,’ or statement, was inaccurate or false,” Frese said.
Tibbetts disappeared after a run in Brooklyn, Iowa, sparking an extensive search that drew national attention.
She had been studying psychology at the University of Iowa and wanted to get a doctorate and write books, her father said. Rivera, meanwhile, had worked for four years at Yarrabee Farms, a nearby dairy farm.
Rob Tibbetts, Mollie’s father, has repeatedly called on politicians to stop using his daughter’s death to make points against immigration, saying she believed these views were “profoundly racist.”
The prosecution based its case on three key aspects: surveillance video of Rivera’s vehicle near Tibbetts, his admissions to investigators in August 2018, and her DNA found in his trunk.
“When you put this evidence together, there can be no other conclusion than that the defendant killed Mollie Tibbetts,” Poweshiek County Attorney Bart Klaver said at the start of the trial.
After initially denying knowing about Tibbetts, he then admitted he had seen her the night she disappeared, said he found her attractive and said he circled back for a second look, Klaver told the jury. He allegedly admitted he had followed Tibbetts and jogged next to her. She had threatened to call the police, and Rivera admitted he got angry and fought with her, Klaver told the court.
“The next thing he remembers” was that he was driving and realized Tibbetts was in his trunk, Klaver said. Rivera allegedly admitted he took her bloody body out of the trunk, carried her into a field and placed corn stalks over her body, according to Klaver.
He then led investigators to the scene, where her body was found hidden under corn stalks, prosecutors said.
Although Rivera did not explicitly tell investigators he stabbed Tibbetts, prosecutors said that was the only conclusion.
“He says that he blacked out. He didn’t black out. He just didn’t tell (an investigator),” Brown said Thursday.
“He’s telling the officers, in telling those statements, ‘I killed Mollie Tibbetts.’ That’s what he’s saying. That’s what the statements all point to,” he added.
Rivera’s testimony in his own defense Wednesday sharply contradicted his earlier admissions, though.
He testified he was taking a shower when two unknown, masked men broke into his trailer and demanded his help. One had a knife and the other had a gun, he said.
He testified that they forced themselves into his black Chevy Malibu and told him to drive toward town. That was when he said they came across a young woman he now knows to be Tibbetts.
Rivera testified that he was told to stop, while the man with the knife exited the car. He said both men then got out of the vehicle and he heard them opening and closing the trunk. When the men left, he said he found Tibbetts’ body in the trunk of the car. He said he took her body out of the trunk, placed her in a corn field and covered her body with corn stalks.
Rivera said he didn’t know why the men sought his help. He testified that he falsely confessed to police because he feared the men would harm his daughter and ex-girlfriend and because he thought telling investigators what they wanted to hear would help him.
CNN’s Ray Sanchez and Carma Hassan contributed to this report.