Family of killer who suffocated wife, her girls, testify hoping to save his life

Sitting on the witness stand, Alberto Sierra’s mother, Mercedes Pedraza, teared up when asked if she loved her son, who is facing the death penalty for snuffing the lives of his estranged wife and her two young daughters.

Read more DeSantis cancels execution of Death Row inmate from Miami amid dementia concerns

“Very much,” Pedraza said in Spanish through a court interpreter.

Pedraza was one of several of Sierra’s family members who testified Thursday in his sentencing trial, hoping to spare him from execution. Sierra, 42, admitted to suffocating his estranged wife, Gladys Machado, 29, and her daughters Julia, 6, and Daniela, 3, with a plastic bag on Nov. 10, 2012. Their bodies were found inside a closet at the Flagami home they once shared three days after they were killed.

Sierra, who has appeared relatively stoic throughout the trial, shed tears as his loved ones walked into the courtroom to testify.

The fate of Sierra is in the hands of 12 jurors who are tasked with deciding whether Sierra, who pleaded guilty to the murders, should be condemned to death or sentenced to life in prison. Miami-Dade Circuit Judge Marisa Tinkler Mendez is presiding.

Sierra’s defense attorneys began presenting their case to the jury on Wednesday. The state rested its case on Tuesday afternoon after Machado, Julia and Daniela’s loved ones spoke about the impact of their loss. Michael Padrino Jr., Machado’s only surviving son, delivered his victim-impact statement Tuesday afternoon.

READ MORE: ‘You took them,’ man says to killer who suffocated his mother, sisters with bag

On the stand Thursday, Pedraza recalled how she, a single mother, struggled raising her two sons in Cuba. She worked a full-time job as a cafeteria worker but said that on the weekends she had to sell fruits and produce from her home to get by.

Sierra, she said, “could not sit still” but was always very social and played with his friends out on the street. She said Sierra moved on to different grade levels but was not a high-achieving student and was “very immature.”

Pedraza also said she sold her grandparents’ home in Cuba to be able to move to the U.S. When the family first arrived, they lived with other relatives in South Florida, she said.

Within months of arriving in the U.S., Sierra was hit by a car, Pedraza said. She said she remembers it was Mother’s Day 1996 and getting a call that Sierra was being taken to Jackson Memorial Hospital as she was out buying a cake to celebrate.

When she arrived to the hospital, she remembered Sierra looking as if he were dead. His face, she said, looked like a mask and was covered in blood. Sierra, she added, also had a large, bloody bump on his head.

Sierra was hospitalized for two weeks, she said. After the accident, Pedraza said she noticed Sierra would have frequent tantrums, refused to follow rules and ultimately dropped out of high school.

“He cried a lot,” Pedraza said. “He got upset over anything.”

Pedraza’s testimony will continue when the trial resumes on Tuesday.

‘A regular kid’

Sierra’s brother, Dayron Porrata, 44, took the stand and recounted how they were raised by their mother and grandparents in Havana. Their mother took up odd jobs to make extra money, Porrata said, including making and selling pizzas and doing hair from home.

Porrata said he and Sierra were “regular kids” in Cuba who played with other kids. Sierra, his brother said, brought home stray dogs and fed them.

“He was outgoing, happy, very hyper, more than me,” Porrata said. “Just a regular kid…”

Read more Carol City High football team gets postseason ban, suspensions after brawl

Porrata recalled how Sierra’s father, who Porrata considered a father figure, separated from their mother but remained present in both of their lives. Sierra didn’t do well in school but liked to take things apart and put them back together, he said.

After the family moved to the U.S. in 1995, Sierra was struck by a car, Porrata said. His recovery was extensive, and Sierra needed help with daily functions, like eating, getting out of bed and showering.

“He was not the same brother,” Porrata said, adding that he still loved Sierra even though he confessed to the brutal crimes.

While questioning Porrata, prosecutor Lara Penn pointed out that Sierra still learned English after the accident, worked several jobs and built his first car’s engine.

Porrata also said he never met Machado and is no longer close with Sierra, although they speak periodically.

Feeridania Pedraza, Sierra’s cousin, said Sierra, his mother and brother all moved in with her family when they arrived from Cuba. Testifying via Zoom from her Tennessee home, Pedraza said that at one point, 15 people lived in the home.

Defense attorney Joyce Brenner showed Pedraza a photo of Sierra as a teenager. Pedraza said that’s the Sierra she remembered.

Pedraza teared up as she recounted about the last time she saw Sierra. He was in the hospital, bandaged up, because he had been hit by a car, Pedraza said.

‘Uncontrolled’ diabetes

On Wednesday, Dr. Leonard Thaler, an endocrinologist, testified that he reviewed 40,000 pages of Sierra’s medical records. Sierra has diabetes that Thaler described as “uncontrolled.”

Thaler said he didn’t see evidence that Sierra’s kidneys are significantly damaged but testified that Sierra’s diabetes “would not get better” and could reduce his life expectancy.

Sifting through pages of medical records, prosecutor Abbe Rifkin highlighted how Sierra once had a seizure in his jail cell after using K2, a form of synthetic marijuana. Rifkin also emphasized two other incidents in which Sierra was acting bizarrely after smoking something and how he once was admitted to the hospital for ingesting a chemotherapy drug.

Sierra, Rifkin said while questioning the doctor, also had capacity to take his medications and had “no problem” asking for what he wanted.

“He refuses treatment, doesn’t follow orders and ingests substances that aren’t good for his diabetes,” Thaler said.

Read more Drea De Matteo couldn’t attend Miami gala, so she did the next best thing

This story was originally published October 8, 2026 at 5:57 PM.