Miami-Dade detectives questioned and released the estranged husband of a slain woman who was found murdered and laid out in a bedroom closet.

Alberto Luis Sierra walked into the Kendall district station Wednesday night, talked to homicide detectives for several hours and was allowed to leave early Thursday.

His release does not eliminate him as a possible suspect in the slaying of Gladys Machado, 29, and her two young daughters. But investigators are continuing their probe and will await processing of forensic, physical and other evidence from the crime scene.

Miami-Dade Police declined to comment.

A neighbor on Tuesday afternoon found Machado and Julia and Daniela Padrino, ages 8 and 4, inside a closet at their Flagami-area home. Police have not released how they died.

Also on Thursday, Beauty Schools of America — where Machado worked as a registrar — donated $5,000 in her honor to The Children’s Trust, an independently financed initiative to help children in Miami-Dade County. Machado’s 6-year-old son was unharmed and was with his mother’s grandmother when the bodies were found.

“Beauty Schools of America is deeply saddened by the loss of Ms. Machado and her two daughters,” the school said in a statement. “Our organization is compelled to assist her son and other children in Miami-Dade County affected by violence.”

Machado was last seen Saturday night when she and her daughters left her grandmother’s Homestead house, where they had been staying since she split with Sierra.

The bodies were not found until Tuesday afternoon some 30 miles north, at the home Machado had lived at with Sierra on the 7300 block of Northwest Fourth Street.

Exactly how the bodies came to be at the vacant home remained a mystery.

Sierra, 28, had a long criminal history that included convictions for drugs and weapons.

In 2010, cops arrested him after he allegedly bit Machado in the arm during an argument. Officers later found him with 79 grams of Ecstasy, a stolen 9mm Smith & Wesson pistol and ammo.

After he was sentenced to one year of probation, he and Sierra were married in October 2011.

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 probe closed when Sierra was again arrested.

In November 2011, he was investigated by detectives investigating another burglary. At the time, he was living with Machado at the same Flagami-area house where she was later found dead.

Officers seized a rifle, a shotgun and ammo. He was charged with possession of a firearm by a convicted felon and his probation was revoked. Sierra later pleaded guilty and was sentenced to 364 days in a Miami-Dade jail.

Sierra was released on June 22 and returned to living with Machado. Exactly why the couple split and when was unclear.

Machado was by all accounts a loving mother, although friends and neighbors say she had her issues. Olga Cecilia Espinoza said she met Machado at daycare where their children played together. The two women became friends and had plans to go out Friday night.

“She was confusing sometimes,” Espinoza said. “She was very quiet with her personal life.”

Machado was born in Cuba, but came to South Florida when she was four.

She married Michael Padrino in 2004 in Miami Beach and the couple had three children. They moved to Homestead in 2007, and it wasn’t long after that the relationship began to unravel.

A neighbor said when Padrino stopped living at the house, Gladys’ grandmother was always helping take care of the children and providing financial support.

Machado and Padrino divorced in February 2011, and married she Alberto Sierra in October of that year. Espinoza said she always knew Sierra was bad news, and warned her friend that he wasn’t good for her or the children.

She thought the couple had broken up, and said Machado had been living with her grandmother for at least a month.

“When we were talking, she was single,” Espinoza said. “She was going out, partying. I don’t know if she had another guy or what.”

A friend spoke with the grandmother who said funeral preparations would wait until the medical examiner’s office had finished its investigation.

Machado’s 8-year-old son is now with his father, who was denied custody of the three children last year, a friend said.