‘Ima kill this baby.’ Fort Worth mom who murdered newborn sentenced to 15-year confinement

The photographs of Dayana Guillen’s brain were among the last of the PowerPoint’s 16 autopsy slides.

Images of external bruises and cuts on the dead little girl’s head were, on six monitors in the jury box and on a larger screen on the courtroom wall, presented first.

Next were fractures in the newborn’s skull. The bone breaks indicated blunt force trauma to the head caused her death, a homicide, Dr. Tasha Zemrus, the chief deputy medical examiner in Tarrant County, told the jurors.

Finally, a photo of the organ beneath was on display.

The brain’s torn tissue revealed, with the split skull, what had happened to Dayana, who lived from 6:20 p.m. on Sept. 9, 2021, to 12:30 a.m. on Sept. 10, 2021.

The breaks were consistent with an impact with a surface, Zemrus concluded.

Upon the little girl’s birth, her mother beat her to death, the Tarrant County Criminal District Attorney’s Office argued to the jury.

The mother became pregnant at 14 after sneaking out of her house to have sex with a neighbor who was about the same age. She delivered Dayana at 15. She is now 17 and will turn 18 next week.

The ninth-grader began to go into labor at school and returned to her family’s mobile home in Fort Worth to give birth in the master bathroom. She had not told not her parents, her three sisters or anyone beyond the baby’s father that she was pregnant.

Blood that was later revealed to police by a chemical agent stained the door, floor and floral wallpaper.

Wrapped in a towel in the bathroom, blood trickling from her legs, the mother refused to hold her baby.

“I don’t want it,” she can be heard saying twice in a recording of her sister’s call to 911.

“Doctor, would it be fair to say that the shards of skull cut up her brain?” prosecutor Kyle Morris asked the pathologist who performed the autopsy.

“Yes,” Zemrus said.

The injuries were not the result of a baby who had been born while her mother was on a toilet and fell a short distance into the bowl, the 15-year-old mother’s first account of how her baby was injured. The mother later formally recanted the explanation when she pleaded true to capital murder and stipulated that Dayana’s death was caused at her hand.

The mother smashed Dayana’s head into the bathroom floor, prosecutor Lee Sorrells argued to the jurors, who were to decide the girl’s sentence.

He emphasized the floor strikes in his closing argument on Thursday by thwacking his hand on the petitioner’s table.

A jury at a disposition hearing in the 323rd District Court, a juvenile court in Tarrant County, on Friday unanimously determined the mother should be confined for 15 years, first in a Texas Juvenile Justice Department facility.

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At a transfer hearing to be held about two weeks before the mother is 19, a judge will determine whether she will continue the sentence in an adult prison or be released from custody under parole supervision.

The district attorney’s office had asked the jury to apply the maximum confinement term of 40 years. The mother’s defense attorneys requested a sentence under 10 years and a designation for probation. The jury deliberated for about six hours and 15 minutes.

Judge Alex Kim earlier denied the state’s request to certify the mother as an adult.

The Fort Worth Star-Telegram does not publish the name of a person who is accused or found delinquent in a juvenile court matter.

The defense strategy focused in part on describing to the jury the mother’s pre-pregnancy upbringing. Her parents expected their four daughters to abstain from sex until marriage, a position connected to their deep Catholic faith. Dayana’s mother had limited sex education, and her parents would never have consented to an abortion, which the law at the time would have required.

“She truly believed you can’t get pregnant the first time,” attorney Lisa Herrick told the jury in the defense opening statement.

Tests indicated the mother has below average intellectual function. Adolescents have an underdeveloped prefrontal cortex that often makes them unable to appreciate consequences in the way an adult would, physiologist Stephen Thorne testified. Still, a 15-year-old would distinguish between right and wrong, Thorne testified.

The defense asked jurors to consider Fort Worth Police Department Detective Christopher Parker’s delay in referring the case to the district attorney’s office and seeking an arrest warrant.

Pathologist Zemrus’ manner of death determination was final in February 2022. The mother was arrested in November 2023.

“Detective Parker did not do his job,” defense attorney Frank Adler said in his closing argument. Parker acknowledged the error when he testified. The detective said the delay was due in part to his work on other cases. Time spent reviewing the suspect’s electronic messages and the detective’s attempts to interview Dayana’s father also contributed to the delay, Parker said.

The filing timing did not change the underlying evidence, prosecutors argued.

The mother avoided discussing Dayana’s death in counseling sessions, though the defense argued that was not evidence of a remorseless person who failed to reflect upon her actions, but rather suggested her dutiful adherence to instruction from an attorney who previously represented her not to discuss the matter.

Dayana’s mother later had a second child. Because of the potentially criminal circumstances of Dayana’s death, a court ordered the second child placed in the custody of a relative. The child has, under supervision, visited her mother in a juvenile detention facility.

Dayana’s father was called as a defense witness. Now 18, Alexis Martinez asserted his Fifth Amendment right against self-incrimination and declined to answer four questions before prosecutor Morris asked Judge Kim to find that further questions and witness response would be unproductive.

Martinez was not charged in the case.

“He is an accomplice, and they don’t care,” Adler said in his closing of Martinez and assistant criminal district attorneys Morris and Sorrells.

Martinez was not in the bathroom in the 5500 block of Parker Henderson Road when Dayana was beaten there.

The district attorney’s office at times charges defendants under the law of parties that holds a person criminally responsible for the conduct of another person if the defendant solicits, encourages, directs or aids the other person to commit an offense. To charge Martinez after he turned 18, the state would be required to demonstrate that law enforcement exercised due diligence prior to his 18th birthday but could not prosecute a case then.

“A couple of the jurors ... flat out told us that was a consideration,” Adler said of the Martinez charging decision. After the verdict, Adler, Herrick and attorney Larry Beaver informally interviewed jurors, a standard practice.

The mother chose not to testify.

Prosecutors Sorrells and Morris showed jurors Snapchat and text message exchanges between the mother and Martinez in which the parents pondered ways in which to end the pregnancy in miscarriage or end the newborn’s life. They discussed punching the mother in the stomach. The mother wrote she could wrap the baby “in a towel and hit it.”

“They were shocked when reading through all the text messages how much [Dayana’s parents] lacked any insight into reality regarding sex education,” Herrick said of the jury. The attorney answered questions from reporters after the verdict.

“Ima kill this baby,” the mother wrote in March 2021.

In a Snapchat message, the mother lamented the pregnancy’s changes to her body.

“omg I can’t wait to have my stomach flat again,” she wrote in August 2021.

The girl held Herrick’s hand and cried as the verdict was read.

“This is a truly tragic case,” Herrick said in news release. “This girl is not a hardened criminal. She was a naive 15-year-old girl who made a mistake, got pregnant, and thought her deeply religious parents would disown her. She hid her pregnancy, had the baby in the bathroom of her parents’ home, and then panicked. She has taken responsibility for her conduct and is deeply remorseful.”

Beaver said the teen has the support of her family, who will “be there when she is released, whether it is next year or in 15 years.”