Rivera trial: Defense calls first witnesses, Tibbetts’ boyfriend returns to testify

On the seventh day for the trial of Cristhian Bahena Rivera, the defense called Dalton Jack back to the stand, as well as Bahena Rivera’s ex-girlfriend and mother of his child.


Kelsey Kremer

Defense attorney Chad Frese hands Dalton Jack, Mollie Tibbetts boyfriend, a phone record to review, while testifing for a second time, during Bahena Rivera’s trail, on Tuesday, May 25, 2021, in the Scott County Courthouse, in Davenport, Iowa. Bahena Rivera is on trial after being charged with first degree murder in the death of Mollie Tibbetts in July 2018. (Pool Photo/Kelsey Kremer/Des Moines Register)

Rachel Schilke, Summer Editor

The defense for Cristhian Bahena Rivera implored the jury to remember its ability to say “no” as it heard testimonies on behalf of the defense during the seventh day of trial for the death of University of Iowa student Mollie Tibbetts.

Defense attorney Jennifer Frese gave the defense’s opening statement on Tuesday, recalling for the jury the graphic photographs and testimonies it had seen over the course of the trial.

“Your heart should break for Mollie Tibbetts. Your heart should break for her family,” Frese said. “Her family deserves justice… but so does Cristhian Bahena Rivera.”

Bahena Rivera is accused of first-degree murder in the connection to Tibbetts’ death. If convicted, he will serve life in prison.

Among witnesses called by the defense on Tuesday were Iris Monarrez Gamboa, the mother of Bahena Rivera’s daughter, and Dalton Jack, Tibbetts’ boyfriend.

Considerable time was spent on Tuesday cross-examining Jack about conversations between himself and Tibbetts regarding his affair, his “anger issues,” and revisiting his whereabouts on July 18, 2018. Jack stated that he was unable to call several details and some of his prior testimony.

“Each one of you have different ways to look at the evidence,” Frese said. “What we’ve asked you to do is listen to our case, fairly, to pay attention, and to remember that each one of you has the power to say ‘no’.”

Michael Spence 

Michael Spence, a doctor that specializes in consulting on reviewing DNA analysis, was the first witness called by the defense to take the stand.

He was contacted in October 2019 to review the reports analyzing DNA evidence in the case for Tibbetts and offer his opinion on whether or not protocols were followed and if he agreed with the conclusions. 

He was not part of the actual testing of evidence, he said, as he does not have his own lab.

Spence testified that he had no issues with the way DNA evidence was analyzed in the case, but it was his opinion that the Iowa Division of Criminal Investigation may have oversimplified the interpretations of mixes of DNA.

For comparative purposes, there were two DNA samples taken: one of Tibbetts and one of Bahena Rivera. However, in the trunk, 17 undocumented alleles were found in one area and 14 in another, Spence said, meaning at least one other person’s DNA was present in the trunk other than Tibbetts’ and Bahena Rivera’s.

One of the alleles, he added, came from a female source other than Tibbetts, and there was another allele belonging to a man other than Bahena Rivera.

“There are other contributors there,” Spence said. “… I would say that it’s typical of a lot of laboratories that they are going to be very oversimplified in interpreting mixtures like that, and a lot of times they’re going to be just written off as uninterpretable or not suitable for comparison.”

He added that when DNA signals are very weak, the comparisons can be used for exclusionary purposes to rule out a certain individual. However, the total 31 alleles that were undocumented could be used for inclusionary purposes, as well, to test against an individual’s sample.

He said this would create a statistical calculation that can give weight to the inclusion.

During cross-examination, prosecutor Scott Brown emphasized that the discrepancies in DNA analysis alone could not prove one way or the other an event, to which Spence agreed. 

“DNA does not come with a timestamp,” Spence said.

Spence testified that other evidence would be needed to determine how the DNA got onto a surface and the timing of the instance. 

“How it got there, the DNA can’t tell you that. Only that it’s there and it’s clearly her DNA,” Spence said. “… The DNA is amazing technology, remarkable technology, very sensitive, but it is never going to give you the history of how something came to be there or the timing of it.

He added that he does not dispute that Tibbetts’ blood and DNA was found in the trunk of the black Chevy Malibu owned by Bahena Rivera.

Alejandra Cervantes Valle

Alejandra Cervantes Valle, who lives in the Tama-Toledo area in Iowa, is married to the uncle of Bahena Rivera. Cervantes speaks some English and has been the spokesperson for the family of Bahena Rivera during the case. 

She testified with the assistance of two translators.

Cervantes Valle came to the United States legally in 2003 when she was 17 years old. She met Bahena Rivera when he was already living in Iowa, who she said arrived illegally.

She said she could not say for sure if Bahena Rivera used a “coyote” to cross the border – an individual that assists with smuggling people over the U.S.-Mexico border.

“All I remember is that they said they needed money. I don’t really remember that much. But they needed money for a coyote,” Cervantes Valle said.

She said prior to July 18, 2018, she saw Bahena Rivera every week at her brother-in-law Lois Medina’s house. She said she would see him at family gatherings such as birthday parties and weddings.

She said she embraced Bahena Rivera as part of the family because he was her husband’s nephew. She said he is very funny and always playing with the family, but around those he does not know, he is shy until he gets to know them.

She added she has never known him to be violent or fight with anyone, and that he was respectful to her brother-in-law, her husband, and children.

“All the children loved him,” she said.

Cervantes Valle said she heard of Bahena Rivera’s involvement in the case twice: once when he was stopped for routine questioning and another when her sister-in-law called her and said he was at the Montezuma police department.

She stayed at the police department from 8:30 p.m. on August 20, 2018, to 1:30 a.m. the next day. She said she attempted to ask officers what was happening and they did not answer her questions or help her.

She said she tried to call and text Bahena Rivera between 8:30 p.m. and 11:30 p.m. but he did not answer.

Cervantes Valle testified that a woman – former Iowa City and West Liberty police officer Pamela Romero – came out to speak with her during Bahena Rivera’s 11-hour interview around 10:30 p.m. on August 20.

“I asked her if we needed an attorney for Cristhian,” Cervantes Valle said. “She said we didn’t need an attorney.” 

During the testimony, Brown asked Judge Joel Yates to strike from the record the specific conversation that Romero had with Cervantes Valle. Frese apologized to Cervantes Valle for the questions she posed during Cervantes Valle’s testimony. 

Cervantes Valle said her conversation with Romero lasted less than five minutes and it was the only time she had contact with Romero.

Iris Monarrez Gamboa

Iris Monarrez Gamboa, the mother of Bahena Rivera’s daughter, was subpoenaed to testify in court.

She said she met Bahena Rivera at a quinceañera in 2013 and they moved in together when she got pregnant. She said she lived with Bahena Rivera at Yarrabee Farms while he was employed there from 2016 to 2017, and their daughter was one year old.

After splitting up, Gamboa said she and Bahena Rivera were able to co-parent effectively. He paid her every other week, totaling to approximately $500 a month. 

Bahena Rivera was sending money to his family, which Gamboa said wasn’t unusual for those who had family in Mexico. She added that the money was to help his parents start building a house in Mexico.

Gamboa said she does not remember coming to the U.S. as she was one year old, and lives in the U.S. legally under Deferred Action for Childhood Arrivals (DACA). Her father got deported, she said, but she does not remember the reasoning.

She added that immigrants who live in the U.S. illegally fear law enforcement because they are afraid they will get deported. 

The prosecution objected to the admittance of a 2017 photograph of Bahena Rivera’s daughter’s second birthday party into evidence, but Frese said given there are no photographs prior to 2018 in evidence, it should be admitted. 

Yates overruled the objection and allowed the photo to be admitted into evidence.

“He was a really good father. He was responsible and always looked out for his daughter,” Gamboa said.

She testified that Bahena Rivera was never violent toward her or their daughter, and never expressed any anger problems. 

She said she was not aware of any time periods where Bahena Rivera claimed to “blackout” or have memory loss. The defense has made the claim that Romero suggested the term “blackout” to Bahena Rivera during his admission on August 21, 2018.

Gamboa, who graduated from Brooklyn, Iowa, said herself and Ulises Felix – Bahena Rivera’s cousin – knew Dalton Jack, Tibbetts’ boyfriend who testified on May 19. 

She said Jack was “pretty racist.”

Ana Young

Ana Young, who works as a lab analyst in the Iowa Division of Criminal Investigation – Crime Lab, has expertise in latent print examination. She has been working in the fingerprint analysis field for 10 years, she said.

She examined 14 items from the trunk of Bahena Rivera’s black Chevy Malibu for latent fingerprints. Of the 14 items, she said she was able to find latent fingerprints on a red ice scraper and a clear storage box with fishing hooks.

Young testified that she found one latent print on the ice scraper and three on the storage box. The latent prints found on the ice scraper and one latent print on the box were impressions, and Young said she was unable to determine if the print came from the palm or a finger, but matched them to Bahena Rivera’s fingerprints.

The remaining two latent prints on the box did not match the fingerprints of Bahena Rivera. 

Young testified that she attempted but could not obtain fingerprints from Tibbetts’ body because of the state of decomposition. 

Dalton Jack

Dalton Jack, Tibbetts’ boyfriend, was called back to the stand by the defense after testifying on May 19. He spent most of his testimony stating he was unable to recall multiple conversations and situations when asked to do so by the defense.

Defense attorney Chad Frese asked Jack questions about Tibbetts as a person and how she interacted with individuals that she knew and strangers.

“Knowing what you know about Mollie Tibbetts, if she were out on a country road jogging and someone comes up and talks to her, she’s the kind of person who would stop and have a conversation with that person,” Frese said. “She would stop and say at least hello.” 

Jack agreed with Frese, and said Tibbetts would not get scared or angry at someone attempting to talk to her unless provoked.

Jack testified that of the two, he became angry more often, and Tibbetts would attempt to calm him down. He added that he does not recall telling anyone that he blacks out when he gets angry. 

He said he was planning to propose to Tibbetts on the beach in Punta Cana, which Tibbetts was already aware of after he “spilled the beans” about his plan.

During the year between the spilled plan and Tibbetts’ disappearance, Jack testified that their relationship went up and down, and that they had discussed breaking up several times.

The relationship was rocky, in part, because of Jordyn Lamb, the woman who Jack had an affair with in 2017. Jack made the prior testimony that his relations with Lamb lasted one day.

In April 2018, Jack and Tibbetts had a conversation about Lamb screenshotting something from Tibbetts’ Snapchat, and another conversation about Lamb allegedly sending screenshots of messages between her and Jack to Tibbetts. 

Many of these conversations brought up by Frese were not recalled by Jack despite the defense providing phone and message records.

According to phone records, Jack only called Tibbetts one time during the span of July 15, 2018 and July 19, 2018. Tibbetts went missing on July 18.

Jack said he graduated with Gamboa but did not know her well. He also testified that he knew Ulises Felix, as well.

When asked if he would share Gamboa’s opinion that he was racist, he said no.

Frese attempted to provide Jack with a record of messages from October 2017 allegedly including derogatory terms towards Hispanics, but was met with objections from the prosecution. 

Jack testified during cross-examination from Brown that he did not see Tibbetts again after July 16, and never made his way back to Brooklyn, Iowa on July 18, 2018.

Jack said he made no effort to conceal anything from officers and was cooperative when authorities asked to search his truck. He testified he did nothing to alter the vehicle, as well.

The defense pointed out that Jack was able to recall that he was working for Jasper Construction when Tibbetts disappeared “clear as a bell,” to which Jack agreed.

Frese probed Jack about drinking with his supervisor and coworkers on the night of July 18. Jack said he did drink to the point of intoxication, and that he remained with the work crew that night.

“… You’d agree with me that the statements you gave to officers regarding your activities and whereabouts on July 18 and July 19 were pretty sketchy… the details were few and far between,” Frese said.

Dalton disagreed, stating he thought the details he provided were sufficient.

“I thought they were pretty clear,” he said.

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