MIAMI (Court TV) — A detective told a Florida jury on Monday that a man confessed to sexually abusing the bodies of his wife and stepdaughter after killing them and leaving their bodies in a closet.
Alberto Sierra sits in court on Oct. 5, 2026. (Court TV)
Because Alberto Sierra, 42, pleaded guilty to murder, burglary, kidnapping and abuse of a dead body in the deaths of his estranged wife, Gladys del Carmen Sierra, and her daughters, Julia, 6, and Daniela, 4, the jury must decide only his punishment. Prosecutors are seeking a death sentence, while his attorneys maintain that the defendant’s profound brain damage means he should serve a life sentence without the possibility of parole.
On Monday, Detective Juan Carlos Chavez testified about his interview with Alberto Sierra in the days after the victims’ decomposing bodies were found in a closet. While Alberto Sierra first claimed that he had been home in his apartment all day, Chavez said that the defendant offered a full confession after he was confronted with the fact that his DNA was found in his stepdaughter’s underwear.
Prosecutor: When you told him that, what happened?
Chavez: “His body language, his demeanor at that point changed. He did drop his head for several seconds, while clasping his hands. He began to quiver and then he decided and stated that he was going to tell me what happened.”
Chavez told the jury that Alberto Sierra said that he, his wife and stepdaughters had gone to the Mall of the Americas for a day of shopping. When the group got back into Gladys del Carmen Sierra’s car to leave, she received two phone calls, which she immediately rejected. Though he was separated from Gladys del Carmen Sierra, Alberto Sierra admitted he was jealous and confronted her about being unfaithful, Chavez said. During the confrontation, Alberto Sierra grabbed Gladys del Carmen Sierra’s phone, which he said prompted her to grab a kitchen knife out of the driver’s door panel.
Alberto Sierra told Chavez that he wrested the knife from his estranged wife and used it to force her to switch seats in the car, so that he was driving with the two girls in the back seat. He said he drove the group back to Gladys del Carmen Sierra’s home, where he pointed the knife at the group and told them, “he won’t hurt them if they don’t scream.”
Chavez said Alberto Sierra brought the three victims upstairs in their home and locked the children in their bedroom before leading Gladys del Carmen Sierra to the master bedroom, eventually tying her wrists behind her back with a nylon rope that was in the house. “According to what he told me,” Chavez said, “he was holding the knife, pricking Gladys with the knife, while her hands were bound, in exchange for the lock code to her phone.”
Gladys del Carmen Sierra eventually gave the defendant the lock code to her phone, and Chavez said the call logs, messages and emails the defendant searched further enraged him. Chavez said Alberto Sierra climbed on top of Gladys del Carmen Sierra, pinned her down and held a plastic bag over her face. “He explained that Gladys was kicking and struggling, what he believed was approximately one minute, as he had her pinned down, forcing the bag over her face, where he says that he turned his face away so that he wouldn’t have to look at Gladys struggling to breathe.”
After Gladys del Carmen Sierra was dead, Alberto Sierra waited an hour before he cut her clothes from her body and sexually abused her corpse, Chavez said, stopping when “he realized it wasn’t right.”
Alberto Sierra told Chavez that, at that point, he heard Julia knock on her bedroom door and ask to be let out to use the bathroom. He allowed her out, but as she left the bathroom, she saw her mother’s nude body on the bed in the master bedroom. “He followed Julia into the room, who by this point had gotten on top of the bed, screaming,” Chavez said, and then used the same bag he had used to suffocate the child’s mother to kill the 6-year-old “by pulling her hair back and placing the bag over her face.” Chavez said that Alberto Sierra then went into the girls’ bedroom, where Daniela was asleep, and suffocated her with the same bag.
Chavez said Alberto Sierra told him that after he dragged Daniela’s body into the master bedroom and left her on the floor of the closet, he sexually abused Julia’s corpse after watching pornography. He then moved the bodies of both Julia and Gladys del Carmen Sierra into the same closet where he left Daniela.
Chavez said Alberto Sierra admitted gathering evidence from the bed and Gladys del Carmen Sierra’s personal items, then cleaning the apartment before leaving “in an effort to destroy any evidence tying him to the scene.”
Prosecutor: Did he tell you that this was something he thought up all by himself? To clean up?
Chavez: Oh yes, that was his intention, to clean up his tracks, so to speak, at the scene.
Prosecutor: Did he ever tell you how his broken brain allowed him to do that?
Alberto Sierra’s defense said in its opening statement to the jury that the defendant has a “broken brain” and severe damage that resulted in the loss of part of his frontal lobe.
