Burglars suffocated a mom while her baby sat in a crib. Murder trial finally started — 28 years later.

The front door was already open when Fermin Cantu Sr. arrived at his Lake Worth home late in the afternoon of Nov. 27, 1990.

He discovered his wife, Minerva, on the living room floor, motionless, her wrists and ankles bound by electrical cords, and a towel and duct tape covering her face.

Testifying in a Palm Beach County courtroom Tuesday, Cantu recalls desperately trying to remove the gag applied by burglars — but it was too late. Minerva, 26, was already dead, though her 18-month-old son was unharmed in his crib in his bedroom.

Police then began a murder investigation which, despite some early leads and sketches of the suspects, remained unsolved until the arrest of Jeffer Negron in 2016.

Cantu, who now lives in Port St. Lucie, was the first witness at the start of Negron’s trial on a first-degree murder charge. While Cantu was on the witness stand, jurors viewed photographs of the crime scene and his wife’s tied-up body.

In his opening statement, Assistant State Attorney Reid Scott said cold case detectives used DNA evidence to reveal Negron as one of the killers.

Scott said Negron’s DNA was identified from scrapings underneath Cantu’s fingernails, and a “distinctive orange shirt” she had been wearing.

Negron, who at the time of his arrest was living about 30 miles south of Raleigh, N.C., has denied any involvement. The prosecutor recently wrote that Negron, 52, told a detective “he did not know the Victim, had never met the Victim, and had never been to her home before.”

But according to evidence to be presented to the jury, “extremely conservative” mathematical computations show that “it is 22 times more likely than not” that Negron’s DNA is on the fingernail scrapings.

The prosecution’s main DNA expert also will testify this week that “it is 117,954 times more likely than not” that Negron’s DNA is on Cantu’s shirt.

Defense attorneys Seth LaVay and Hilliard Moldof call that a “dubious statistical DNA analysis.”

They are planning to bring in their own experts to explain the DNA evidence was based on “gross disqualifying errors.”

In a pleading filed with the court in March, LaVay also wrote the burglars didn’t intend to kill Cantu.

“Accidentally, the cloth and duct tape gag around the victim’s mouth was applied too tightly, causing the victim to expire by suffocation,” he wrote.

Prosecutors had long intended to seek the death penalty in the case, but abandoned that plan a few months ago.

Still, they will argue that Negron, who is also known as “Jesse,” had scoped out the Cantu house, at 421 North F St., prior to the burglary.

The prosecution’s witnesses include one of Negron’s former friends, who says Negron once told him about the violence in the Cantu home.

When the perpetrators entered the home, Minerva Cantu was there with her toddler son, while her 8-year-old daughter was at school and her husband was at work.

Fermin Cantu and Minerva’s niece arrived about 5:50 p.m. that day, and found Minerva’s body, according to a South Florida Sun Sentinel story published in 1990. The niece ran out of the home screaming for help and got the attention of neighbor Mary Smith that day.

“She came running over here, hollering for me to call an ambulance. At first, they thought [Minerva Cantu] was just hurt,” Smith said in 1990.

One of the family cars, a red 1984 Mercury Cougar, and jewelry were missing, Fermin Cantu testified Tuesday. Police found the car about six blocks away, but leads never resulted in any arrests back then.

State records show Negron has been arrested six times since the 1990s; he was convicted of trafficking cocaine in 1993, records show.

The trial before Circuit Judge John Kastrenakes is expected to continue through the rest of the week.