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Defendant Alberto Sierra, who is accused of murdering his wife and her two young daughters, takes the oath during a hearing presided by Judge Marisa Tinkler Mendez, ahead of his trial. He is facing the death penalty. Sierra pleaded guilty in Courtroom 4-6, at the Richard E. Gerstein Justice Building, on Friday, Aug. 7, 2026.<\/p>\n
Pedro Portal<\/p>\n
pportal@miamiherald.com<\/p>\n
The trial of a man who admitted to suffocating his estranged wife and her two young daughters with a plastic bag more than a decade ago began Monday morning with jury selection.<\/p>\n
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 two weeks, hundreds of the jurors will be questioned on their thoughts about the death penalty.<\/p>\n
The pool will be whittled down to a 12-person jury that will be tasked with deciding whether Sierra should be condemned to Florida\u2019s Death Row or sentenced to life in prison. The jurors selected won\u2019t have to decide on Sierra\u2019s guilt because Sierra entered a guilty plea during a hearing on Aug. 7.<\/p>\n
READ MORE: He killed his wife and her two young girls. Jury will decide if he gets to live<\/a><\/p>\n Sierra admitted to suffocating Gladys Machado, 29, and her daughters Julia Padron, 8, and Daniela Padron, 4, on Nov. 10, 2012. Three 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.<\/p>\n Sierra was charged with three counts of first-degree murder and kidnapping, two counts of abuse of a human body and one count of burglary.<\/p>\n Opening arguments are expected to begin after a jury is seated by early September.<\/p>\n The crime shocks Miami<\/p>\n Machado and Sierra, who had a history of domestic violence, split up shortly before the killings. Machado, a mother of three, moved in with her grandmother in Homestead while Sierra stayed with his mother at her townhome in Kendall.<\/p>\n On the evening of the murders, Machado went on a shopping trip with her two daughters, leaving her 6-year-old son with her grandmother, court records indicate.<\/p>\n Sierra accompanied Machado and her daughters to the Mall of the Americas in West Miami-Dade in Machado\u2019s 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.<\/p>\n The Altima was not spotted again until Nov. 19, when police officers discovered it parked in a guest spot at Kendall\u2019s Calusa Club apartments, 8810 SW 132nd Ave., across the street from the home of Sierra\u2019s mother.<\/p>\n The Altima was backed into bushes \u201cso as to conceal the tag number,\u201d according to police. Inside, investigators found blood on both the passenger and driver\u2019s side seats.<\/p>\n When questioned by police days after the murders, Sierra confessed to the crimes:<\/p>\n 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.<\/p>\n 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.<\/p>\n Not his first problems with the law<\/p>\n The murders unfolded five 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.<\/p>\n The state Department of Children and Families also investigated Sierra because Julia told a teacher her stepfather had \u201cbit me with his teeth.\u201d Child-welfare investigators determined that the bite was child abuse, although Miami-Dade police concluded that Sierra had bitten the girl \u201cplayfully.\u201d No charges were filed in connection to that incident.<\/p>\n This report was supplemented with information from the Miami Herald\u2019s archives<\/p>\n![\"Julia,](\"https:\/\/www.newsbeep.com\/us-fl\/wp-content\/uploads\/2026\/08\/IMG_IMG_ninasFOTO_5_1_DL_11_1_IP6BCFKQ.JPG\" "\\"IMG_IMG_ninasFOTO_5_1_DL_11_1_IP6BCFKQ.JPG\\"")
Julia, 8, and Daniela, 4, were killed alongside their mother Glady Machado, 29, on Tuesday, November 13, 2012. Handout <\/p>\n![\"Glady](\"https:\/\/www.newsbeep.com\/us-fl\/wp-content\/uploads\/2026\/08\/IMG_IMG_muertosGLADYS_5__11_1_IP6BCFKL.JPG\" "\\"IMG_IMG_muertosGLADYS_5__11_1_IP6BCFKL.JPG\\"")
Glady Machado, 29, and her two daughters were killed on November 13, 2012. Miami Herald File <\/p>\n Alberto Sierra, accused of murdering his wife and her two young daughters, plus raping the woman and one of the girls appears in court on Thursday, Jan. 31, 2013. Walter Michot Miami Herald File <\/p>\n
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