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Florida | Future of man who admitted to killing wife, young girls will be up to Miami jury

Alberto Sierra
The trial of a man who admitted to suffocating his estranged wife and her 2 young daughters with a plastic bag more than a decade ago began Monday morning with jury selection. 

Sandwiched by his attorneys, Alberto Sierra, 42, sat in a navy blue sweater as dozens of prospective jurors shuffled into the largest courtroom in the Richard E. Gerstein Justice Building in Miami. 

In 2 weeks, hundreds of the jurors will be questioned on their thoughts about the death penalty. 

The pool will be whittled down to a 12-person jury that will be tasked with deciding whether Sierra should be condemned to Florida’s death row or sentenced to life in prison. 

The jurors selected won’t have to decide on Sierra’s guilt because Sierra entered a guilty plea during a hearing on Aug. 7. 

Sierra admitted to suffocating Gladys Machado, 29, and her daughters Julia Padron, 8, and Daniela Padron, 4, on Nov. 10, 2012. 3 days after the slayings, a neighbor found their bodies inside a bedroom closet in their Flagami home in the 7300 block of Northwest Fourth Street. Julia, 8, and Daniela, 4, were killed alongside their mother Glady Machado, 29, on Tuesday, November 13, 2012. 

Sierra was charged with 3 counts of 1st-degree murder and kidnapping, 2 counts of abuse of a human body, and one count of burglary. 

Opening arguments are expected to begin after a jury is seated by early September. 

The crime shocks Miami 


Machado and Sierra, who had a history of domestic violence, split up shortly before the killings. Machado, a mother of 3, moved in with her grandmother in Homestead while Sierra stayed with his mother at her townhome in Kendall. 

On the evening of the murders, Machado went on a shopping trip with her 2 daughters, leaving her 6-year-old son with her grandmother, court records indicate. 

Sierra accompanied Machado and her daughters to the Mall of the Americas in West Miami-Dade in Machado’s 2004 gold Nissan Altima. A woman living at an efficiency near the home saw the Altima that night but said it was gone by 11:30 p.m. The Altima was not spotted again until Nov. 19, when police officers discovered it parked in a guest spot at Kendall’s Calusa Club apartments, 8810 SW 132nd Ave., across the street from the home of Sierra’s mother. 

The Altima was backed into bushes “so as to conceal the tag number,” according to police. Inside, investigators found blood on both the passenger's and driver’s side seats. 

When questioned by police days after the murders, Sierra confessed to the crimes. He told detectives that he stabbed Machado inside her car after she, in his presence, took a phone call from another man. 

He then drove her and her daughters to their home. There, Sierra suffocated them with a plastic bag. 

Sierra also raped Machado and Julia after they were dead, investigators say. 

DNA samples taken from Julia matched Sierra. 

Fingerprints at the scene were also linked back to Sierra, according to prosecutors. 

Not his first problems with the law 


The murders unfolded 5 months after Sierra was released from jail for violating probation after police located a gun inside the home. Sierra, who had been convicted of drugs and weapons charges, could not possess a firearm. 

The state Department of Children and Families also investigated Sierra because Julia told a teacher her stepfather had “bit me with his teeth.” Child-welfare investigators determined that the bite was child abuse, although Miami-Dade police concluded that Sierra had bitten the girl “playfully.” No charges were filed in connection to that incident.

Source: miamiherald.com, Grethel Aquila, August 17, 2026




"One is absolutely sickened, not by the crimes that the wicked have committed,
but by the punishments that the good have inflicted."
— Oscar Wilde
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