Faced with damning DNA evidence, police say, Alberto Luis Sierra finally confessed to suffocating his estranged wife and two young step-daughters with a plastic bag — and raping the oldest girl after she was dead.
His arrest early Tuesday capped a furious police investigation into the brutal triple slaying of Gladys Machado, 29 and Julia and Daniela Padrino, ages 8 and 4. A neighbor found their bodies last week laid out inside the master bedroom closet of a home where the couple used to live.
The shocking details emerged Tuesday as Miami-Dade police charged Sierra, 28, with three counts of first-degree murder and two of sexual battery.
He was being held without bail at the main Miami-Dade County Jail. Prosecutors likely will seek the death penalty, though the decision is weeks away.
Sierra, a convicted felon, was long the main focus of the investigation and confessed Monday night after hours of questioning.
The couple recently split up. Machado, a mother of three, had been living with her grandmother in Homestead while Sierra had moved into his mother’s townhome in Kendall.
Machado was last seen the evening of Nov. 10 when she left Homestead for a shopping trip with her two daughters. She left her 6-year-old son with her grandmother.
According to an arrest report, Sierra accompanied Machado and her daughters to the Mall of the Americas in Machado’s gold Nissan Altima.
When Machado received a phone call from another man, the two began to argue. Sierra grabbed a knife in the car and stabbed her.
He then drove Machado and her children back to their former home in Flagami, less than two miles from the mall.
There, Sierra locked the daughters in an adjacent bedroom and tied up Machado in the master bedroom, demanding the password to her phone.
Using a plastic bag, he suffocated her. After she died, Sierra raped her, according to the report.
Then, he turned his attention to the children, according to the police report by Miami-Dade Detective Juan Chaidez. The oldest daughter, Julia had knocked on the door asking to go to the bathroom. Sierra allowed her out and suffocated her. He suffocated Daniela, who had fallen asleep. According to the report, Sierra returned the master bedroom, where Julia’s body was, and raped her.
He placed all three bodies in the closet, cleaned the inside of the house and left.
The bodies were found three days later by a woman who rents an efficiency attached to the home.
Police began looking for Sierra, who voluntarily walked into the Kendall substation the following night, telling homicide detectives that he was at his mother’s home that weekend.
With not enough evidence to charge, detectives allowed Sierra to leave.
Within a few days, Miami-Dade’s crime lab identified Sierra’s DNA on Julia’s body. They also found Machado’s missing gold Altima parked not far away from Sierra’s Kendall home.
Sierra is no stranger to the law.
Back in 2010, Machado told police he bit her arm during a heated argument. Investigators later found him with 79 grams of Ecstasy, a stolen 9mm Smith & Wesson pistol and ammo. He served one year of probation.
That same month, Sierra was also investigated by the state’s child welfare agency after Julia told a teacher that her stepdad had bitten her on the arm.
The girls’ biological father asked for sole custody of the children, but the Department of Children and Families closed out its investigation when Sierra was arrested in November 2011 on charges of possessing a firearm by a convicted felon.
After officers seized a rifle, a shotgun and ammo, his probation was revoked. Sierra later pleaded guilty and was sentenced to 364 days in a Miami-Dade jail.
In June, Sierra was released returned to living with Machado.
Sierra’s ex-wife, Michelle Quintana, said on Tuesday that although he never had a job and smoked too much marijuana, he “was the sweetest guy on earth.”
“He was always laughing, making jokes from the time he woke up in the morning,” she said. “My memories were completely different than the monster that he became.”
Sierra’s mother, Mercedes Pedraza, told Quintana that her son is not capable of the horrific crimes described in his police confession.
Pedraza is employed at the Beauty Schools of America where Machado also worked.
Jeff Gonzalez, the school’s executive director of operations, said his employees, especially those who were close to Machado, were “breathing a sigh of relief” that an arrest had been made.