Killer calmly confessed to suffocating his wife, her 2 girls with a plastic bag

Crime admin October 5, 2026 0 Comments

Killer calmly confessed to suffocating his wife, her 2 girls with a plastic bag

After a week of already grueling testimony, jurors in the death-penalty case of Alberto Sierra heard the killer calmly detail to detectives exactly how he snuffed the lives of his estranged wife and her two young daughters with a plastic shopping bag.

Miami-Dade Det. Juan Chaidez testified that he took Sierra’s confession on Nov. 19, 2012, more than a week after the Nov. 10 murders of Gladys Machado, 29, and her daughters Julia Padrino, 6, and Daniela Padrino, 3. Chaidez, the lead investigator, had quickly narrowed in on Sierra, 42.

The 40-minute statement, in which Sierra elaborated on how he committed the murders in a nonchalant manner, was played for the jury Monday morning.

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 left Machado, Julia and Daniela inside a closet at a Flagami home they once shared with Sierra. The bodies were found beside one another three days after they were killed.

Last week, Dr. Emma Lew, the forensic pathologist who performed the autopsies, explained the injuries found on the bodies of Machado and her daughters. She testified that a person being suffocated would be aware of their impending fate and could take minutes to die. Prosecutor Abbe Rifkin described it as a “slow death.”

READ MORE: Evidence shows mother, 2 girls suffered ‘slow death’ as killer suffocated them

On the stand, Chaidez said he initially interviewed Sierra on Nov. 14, swabbed him for DNA and let him go. It wasn’t until days later that Sierra confessed — when the detective confronted Sierra about how his DNA was discovered “where it shouldn’t have been” on Julia’s underwear.

Several jurors closed their eyes briefly and appeared to subtly shake their heads as they heard Sierra’s confession. Sierra looked down at the table as the sound from the video echoed in the large courtroom.

When Chaidez confronted Sierra with the DNA results, the detective said he noticed Sierra’s body language changed instantly. He dropped his head, quivered and told the detective he was going to detail what unfolded the day of the murders.

The original interrogation, which Chaidez called a “pre-interview,” was not recorded in accordance with the Miami-Dade Police Department’s policies. Detectives then recorded Sierra confessing a second time.

Sitting still with his leg up in a chair, Sierra calmly outlined what happened:

What began as a day of shopping at the Mall of the Americas for a birthday present for Daniela, who was days shy of turning 4, ended with Sierra suffocating his wife and his two stepchildren and concealing them in a closet in the home they once lived in as family.

After taking the girls out for ice cream, they got back into Machado’s gold 2004 Nissan Altima. In the middle of the drive from their outing, Machado rejected two calls from a new love interest. That enraged Sierra, who said Machado was “cheating” on him even though the pair was separated.

Sierra told detectives that Machado, who was driving, retrieved a knife from her car’s glove box and tried to attack him. He said they struggled over the knife, and Machado sustained cuts on her hands. But prosecutors disputed that story, pointing to how the Miami-Dade Medical Examiner’s Office determined that Machado had defensive wounds all over her hands from the ambush in the car.

The girls, Sierra said, tried to defend their mother. He elbowed them to contain them in the backseat. Julia and Daniela, Sierra said, were repeatedly exclaiming “Papi, no, Papi, no.”

When they arrived at the home, Sierra said he wanted to check Machado’s phone because she had been unfaithful, but Machado refused to give up her passcode. Sierra then tied Machado’s hands up with a nylon rope and threatened her with a knife. She ultimately gave him the passcode.

Machado was on a bed when Sierra placed his leg on her chest to keep her from moving and wrapped a yellow Sedano’s Supermarket plastic bag over her face.

She was kicking and struggling, Sierra said, causing him to turn his face away so he wouldn’t have to look at her struggling to breathe. Sierra did not mention how he stabbed, sliced and carved parts of Machado’s body before and after she died.

“I was devastated with what I had done,” Sierra said in the recording, adding that he was crying and felt “crazy.”

But, an hour after the attack, Sierra decided to take Machado’s clothes off. He cut off Machado’s shirt and bra with a pair of scissors and had sex with Machado’s body. He told detectives he stopped 10 minutes into the act because it “wasn’t right.”

Shortly after, Julia knocked on the door, asking to use the bathroom. In a panic, Julia started screaming when she saw her mother’s body, and Sierra said he placed the girl face down on the mattress.

Sierra said he grabbed the same plastic bag he used to kill Machado, pulled back Julia’s hair and placed it over her face. Julia, he said, was kicking and trying to break free, so he used his body weight to restrain her and his knees to pin her arms to the bed.

Sierra then turned to Daniela, who was sleeping face down on her bed. Sierra said he crept up behind the toddler, whom he called “Danielita” in his statement, and straddled her body, covering her head with the bag.

Daniela, he said, woke up and struggled with him but fought much less than Machado and Julia. He said he picked Daniela up by her armpits from behind and placed her in the closet.

According to the statement, Sierra then undressed Julia and watched about 10 minutes of porn videos on his phone. He sexually assaulted the girl’s body for about five minutes before “realizing it was wrong,” according to the detective. Sierra said he dressed Julia and dumped her in the closet beside her sister.

Sierra’s account of events conflict with Dr. Lew’s testimony. The blood and nature of the injuries to Julia’s genitals, which Lew described as being “pulled apart,” indicated the child was alive and likely in significant pain during the rape.

Before cleaning up the scene with bleach, Sierra dragged Machado’s body into the closet. He also admitted to parking Machado’s car 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 car was backed into bushes to obscure the license plate, Chaidez said.

Sierra took Machado’s watch, which was given to her by her new love interest, and her cellphone, which has never been recovered, Chaidez said. The plastic bag Sierra used to kill Machado and her daughters and the rope he used to restrain Machado have never been found either.

When Chaidez transported him to jail, Sierra said, “I gave her my life and she s–t on it,” according to the detective.

READ MORE: Bloody clothes shown to jury in case of man who suffocated wife, two girls

Chaidez took the stand last week, although the remainder of his testimony was postponed to Monday due to a scheduling conflict. During that round of Chaidez’s testimony, Rifkin showed the jurors several key pieces of evidence gathered in this case, including Machado’s torn up shirt and the girls’ stained clothing.