Trial begins for killer who ‘tortured’ wife, her girls with plastic bag

Crime admin September 30, 2026 0 Comments

Trial begins for killer who ‘tortured’ wife, her girls with plastic bag

Alberto Sierra lured his estranged wife and her two young daughters for a day of shopping that ended with him snuffing out their lives with a plastic Sedano’s Supermarket bag, raping two of their bodies and leaving the family to rot in what was once their Miami home.

And for that, he should die, prosecutor Abbe Rifkin alluded to the jury.

But defense attorney Joyce Brenner told jurors that they should look to Sierra’s life story, including his brain damage, for reasons to spare him from the death penalty.

The trial of Sierra, 42, began Tuesday afternoon with opening statements before Miami-Dade Circuit Court Judge Marisa Tinkler Mendez. The jurors are tasked only with deciding whether Sierra should be condemned to Florida’s Death Row or sentenced to life in prison for the murders of Gladys Machado, 29, and her daughters Julia Padron, 6, and Daniela Padron, 3.

In August, Sierra pleaded guilty to three counts of first-degree murder and kidnapping, two counts of abuse of a human body and one count of burglary.

“This proceeding is about the lives that were taken, the way they were taken … and the punishment the law provides for crimes of this magnitude,” Rifkin said.

Brenner acknowledged the gruesome nature of the murders — and said Sierra will be held accountable for the killings, regardless of the punishment he ultimately receives.

“Alberto Sierra is responsible for these crimes. He admitted it when he pled guilty,” Brenner said. “He will be punished, that is a certainty.”

‘Slow and brutal,’ prosecutors say

Turning to the jury, Rifkin took them through the first clue that something was wrong on Nov. 10, 2012: Loved ones of Machado had tried calling her, but those calls went unanswered. In voicemails played in court, they were alarmed by not hearing from Machado and her daughters, Julia and Daniela.

READ MORE: He killed his wife and her two young girls. Jury will decide if he gets to live

“If you don’t call me immediately, I’m going to call the police because you’re missing,” a woman said in one of the voicemails played during the trial.

Machado and her daughters were never seen or heard from again until the “unmistakable smell of something rotting” led a neighbor on Nov. 13, 2012, to enter the home, where she “discovered the horror that brought us here today,” Rifkin said.

On the day of the killings, Machado, who was staying with her grandmother in Homestead due to her separation from Sierra, headed to go shopping with Julia and Daniela. Her son, who was 5 at the time, didn’t join them because he wanted to watch “Caso Cerrado” on TV with his grandmother.

READ MORE: Jury chosen in death-penalty trial of man who killed wife and her two daughters

Machado picked up Sierra, and the four of them headed out to purchase a birthday gift for Daniela, who was days shy of turning 4. Sierra, Rifkin added, had told his mother he was going to win Machado back during their outing.

But while they were in the car, Machado received a phone call from a new love interest — and that enraged Sierra, Rifkin said. He attacked Machado with a knife, cutting her hand and causing her to bleed profusely. Julia and Daniela started to scream, so he elbowed them and, holding Machado at knifepoint, took control of the car and headed to the home they all once shared as a family.

At the house, Sierra restrained Machado, tying her hands behind her back, the prosecutor said. He carved up her face so she wouldn’t “be pretty for any other man again,” the prosecutor added.

“He terrorized her. He tortured her. He humiliated her,” Rifkin said. “He decided that Gladys would not leave that house alive.”

Holding a yellow Sedano’s bag, Rifkin told the jury Sierra placed a plastic bag just like it over Machado’s head and suffocated her. Several of Machado’s family members stepped out as the prosecutor detailed the killings.

He then turned to the children, who were locked in a bedroom. Julia became hysterical when she saw her mother’s body — and “at that point, he knew she had to die, too,” the prosecutor said.

Sierra restrained Julia, suffocating her with the bag until she stopped kicking. He raped the child, later telling police he had to watch porn to get aroused, Rifkin said. He also maintained that Julia was already dead, although the prosecutor said the girl’s body says otherwise.

Sierra then crept up on the bed, where Daniela was asleep. He straddled her tightly — to the point she couldn’t move — and suffocated her with the same plastic bag, Rifkin said.

He placed their bodies in the closet, cleaned up and left. He took Machado’s phone and purse with him and disposed of them. That’s when he started planning his story, the prosecutor said. He called Machado, knowing what he had just done to her and her daughters.

“He went about his life without a second thought to what he had done,” Rifkin said.

The case is not a whodunit, and the evidence quickly pointed to Sierra, according to the prosecutor. When detectives confronted him about DNA found on the bodies, he confessed, recounting in detail how he carried out the grisly crimes.

“He killed them in a slow and brutal way,” Rifkin said. “He violated two of them.”

He will be punished, defense says

Facing the jury, Brenner said they will be exposed to horrific photographs that will stay with them for the rest of their lives. The attorney said it would be “completely natural” for the jurors to want vengeance due to the brutality of the crimes, but she urged them to keep an open mind.

“You will think ‘Who could do this? How could this happen?” Brenner said. “The evidence is disturbing and will be difficult for everyone…”

Sierra, she said, was born in Cuba. He had a happy childhood, flying kites and playing with other children in his neighborhood. But when he and his brother were young, his father left his mother, and she struggled financially to support the family.

The family moved to the U.S. in the 1990s to join relatives in South Florida. Within months of their arrival, Sierra was pummeled by a car while he was rollerskating or skateboarding, Brenner said. And since that incident, he has never been the same, the attorney added.

Sierra has profound brain damage, Brenner told the jury. He is missing part of the frontal lobe of his brain and is prone to seizures. At age 21, he was diagnosed with diabetes, which Brenner said also affected his brain.

Sierra’s “broken brain” impacted his formative years, Brenner said. He struggled in school, hung out with a group of misfits, dabbled in drugs and, when he got older, couldn’t hold down a job.

Sierra, Brenner said, was “lost” when he met Machado. They had a passionate but toxic relationship, and Sierra took in his stepchildren, whom Brenner said he loved.

“Life in prison without the possibility of parole is a harsh punishment,” Brenner said. “And Alberto will be punished.”

This story was originally published September 29, 2026 at 4:21 PM.