The prosecution has rested its case against Cristhian Bahena Rivera, who faces a first degree murder charge in the killing of Iowa college student Mollie Tibbetts, who went missing in 2018. While defense attorneys for the Poweshiek County farm hand have sought to cast doubt on other persons of interest in Tibbetts’ death, prosecutors have worked to clear other men who were targets of investigation, including her boyfriend.
The defense is slated to begin calling its own witnesses on Tuesday. Jurors are expected to begin their deliberations this week.
Bahena Rivera has pleaded not guilty and faces life without the possibility of parole if convicted.
Prosecutors called their final witnesses to the stand Monday, some of whom detailed the other people officers looked into, including local sex offenders and Tibbetts’ boyfriend, Dalton Jack.
Investigators had previously testified that Jack had been working at a construction site in Dubuque when Tibbetts went missing while on a run in her hometown of Brooklyn on the evening of July 18, 2018.
But Jack had given inconsistent accounts in interviews with law enforcement officers, initially saying he had been in his motel room watching movies at the time of her disappearance; last week Jack testified he had been drinking and playing yard games with other workers on the construction crew.
Jack had also had an affair with another woman and the couple had discussed ending their relationship in the month before Tibbetts went missing.
Other individuals that investigators looked into included virtually every person listed on the Poweshiek County sex offender registry, agent Trent Vileta of the Iowa Division of Criminal Investigation testified Monday. Officers also looked closely into a number of others, including a man who lived near where Tibbetts’ body was ultimately found, a man whom tipsters reported was known to make threats of violence against women.
But Vileta, who had supervised the Tibbetts investigation, testified Monday that it was only Bahena Rivera who admitted to following Tibbetts, getting angry with her, and ultimately hiding her body in a cornfield.
“Were you able to develop any information from any of the men…including Dalton Jack…any information from any of those men that they made admissions that Mollie Tibbets was in the trunk of their car?” asked prosecutor Scott Brown, pounding the table with his fist for emphasis.
“No,” Vileta replied. “Just Cristhian Rivera is the only one that told us that.”
Investigators detail the role of cell phone data in search
Tibbetts’ disappearance in 2018 from her hometown of about 1,700 people prompted a massive search operation, with friends, family, neighbors, volunteers and law enforcement combing the area for any sign of the 20-year-old University of Iowa student, who was known as a loving daughter and devoted friend.
Airplanes and hospital helicopters were marshalled in the search effort, Vileta testified, which was initially focused on the town of Brooklyn.
It was data from Tibbetts’ cell phone and from her Fitbit that helped officials refocus their search efforts in what was a sprawling multiagency operation. Officers searched for but were never able to find her phone and Fitbit.
But by working with her cell phone carrier and app developers like Google and by analyzing cell tower data, investigators were able to study Tibbetts’ past running routes and compare them to data plotting her phone’s general location and speed of travel at the time of her disappearance.
FBI agent Kevin Horan testified that at around 8:28 p.m., Tibbetts’ phone data indicated she had been running east of Brooklyn at about a 10 minute per mile pace. But soon after that time, the phone reappeared some four to five miles to the south, traveling at roughly 60 miles per hour, suggesting Tibbetts had been in a car. Her phone went dark in rural Poweshiek County at around 8:53.
“We now had a spot where we believe she was taken from. And we also now had a spot where we knew her phone was, which was radically different than being up in the Brooklyn area,” Horan said. “So it really did change things for the investigation.”
The DCI’s agent Vileta estimates that investigators’ searches came within a quarter to a half mile of the field where Tibbetts’ body was hidden beneath cornstalks. But it wasn’t until Bahena Rivera led officers to the location that they were able to find the remains.
Lack of Spanish speakers delayed police interview with Bahena Rivera
It was over the course of an 11-hour interview, conducted entirely in Spanish, that Bahena Rivera told officers Pamela Romero and Jeff Fink that he had followed Tibbetts while she was running, became angry with her when she threatened to call the police, and then allegedly “blacked out."
Officers said he told them he came to when he was driving and remembered that Tibbetts was in the trunk of his car. A DNA analyst testified last week that blood found in the trunk of his black Chevy Malibu matches Tibbetts’ own genetic profile.
Vileta revealed Monday that the August 20 interview with Bahena Rivera, which concluded with him leading officers to Tibbetts’ body, was delayed because none of the investigators spoke Spanish sufficiently.
“We didn’t have any Spanish speakers,” Vileta sad. “It was a nervous time for us because we would have rather done it right away, but we had to basically marshal our resources before we could move forward.”
Romero, a native Spanish speaker who was at the Iowa City Police Department at the time, was called in to conduct the interview despite a relative lack of experience. She failed to read Bahena Rivera his Miranda Rights properly, prompting the court to prevent some of his statements from being used as evidence.
Witnesses detail autopsy findings
The state’s final witnesses detailed the autopsy of Tibbetts’ body conducted by Iowa State Examiner Dennis Klein and a forensic analysis conducted by Des Moines University professor and forensic anthropologist Heather Garvin.
Members of the jury were shown graphic photos taken of Tibbetts’ body during the autopsy. Klein described her remains as moderately to severely decomposed. The state of her remains made it more difficult to draw firm conclusions about some of her injuries, he said.
Klein said he calculated that Tibbetts suffered 9 “definitive wounds” and that he had suspicions of “up to 12” wounds. He identified injuries to her head, neck and ribs, some of which were etched into the bone.
All were apparently caused by a sharp force object such as a knife and one wound was severe enough to penetrate Tibbetts’ skull, an injury which in and of itself could have been fatal, Klein testified. Klein also identified a defensive wound on one of Tibbetts’ hands, evidence that she had fought back against her attacker.
