Oralia Mendoza and Mariah Lopez (Madison County Sheriff’s Office)

Oralia Mendoza’s fatal mistake, it seems, was sharing her worries via text message.

The 49-year-old Alabama grandmother had become dangerously entangled in the Mexican Sinaloa drug cartel — even trying to move a quarter-kilo of meth from Norcross, Ga., to Huntsville, Ala., as recently as June, prosecutors said according to Al.com. In the car with her that day: her cartel-connected boyfriend Yoni Aguilar and a man she used to date named Israel Palomino.

But things had soured on the trip. The men in the car feared a double-cross and Mendoza suddenly felt that she was in danger.

And not just herself. Mendoza was the primary caretaker of her 13-year-old granddaughter, a middle-schooler on the autism spectrum named Mariah Lopez.

So Mendoza thumbed out a text message to an unknown friend, prosecutors said, hinting at the danger and asking the woman to pick up Mariah so she would be safe.

But Aguilar and Palomino discovered the message, investigators say, and decided that Mendoza had to be silenced, as Huntsville ABC-affiliate WAAY reported. The two men, who authorities say were trafficking drugs in Huntsville, had the most to lose if Mendoza’s fears overwhelmed her or her secrets seeped out.

Early on June 4, the men woke up Mendoza and Mariah in their Huntsville home and told the pair they were taking them to a safe place.

Instead, prosecutors said, they took them to Moon cemetery 15 miles southeast of Owens Cross. Palomino stabbed Mendoza several times, leaving her to bleed to death among the tombstones.

Watching from the car, Aguilar would later tell investigators, was Mariah — the only living witness to the killing.

A farmer found the girl’s body on June 7. Her head had been sawed off her body. Investigators had to review her dental records to determine who she was.

She had been a student at Challenger Middle School, according to AL.com. She was on the school’s honor roll.

Her family sat in the courtroom during a court hearing for Aguilar last week, weeping as prosecutors recounted details, including how they connected Aguilar and Palomino to the killing.

After the farmer called authorities, investigators released details about an unidentified body to the public: a female whose height could not be precisely determined, found wearing red pajama pants with a print of gingerbread men, a pink undershirt and a black tank top.

Perhaps more telling, she had a cerebral shunt medical device, used to relieve swelling of the brain caused by certain medical conditions.

A short time later, Mariah’s biological mother walked into the sheriff’s office, Al.com reported. Mariah was missing and fit that description, she said. Mendoza couldn’t be located, either.

Investigators said Aguilar and Palomino’s cellphones connected to cellphone towers in the area where Mariah’s body was found. They also found two knives thought to be the murder weapons — one under Palomino’s mattress, and another under Aguilar’s — and blood in Palomino’s car.

Both men are charged with two counts of capital murder.

According to CNN, the Sinaloa cartel is North America’s most powerful drug-trafficking organization, despite the arrest of Joaquin “El Chapo” Guzman in 2014. As The Washington Post’s Nick Miroff wrote last year, the cartel “does not bother with retail-level commerce, according to the DEA. It uses New York to deliver large wholesale shipments to middlemen, typically local Dominican traffickers. Those groups distribute to markets in New England, Pennsylvania, Baltimore and other places where the opioid crisis is raging.”

According to CNN, about 80,000 people have been killed since 2006 in organized-crime incidents related to the drug war.

One of the latest victims, prosecutors say, is the Huntsville middle-schooler.

After her death, the parent-teacher association at her school set up a memorial fund to help with funeral expenses.

“Our Challenger family has been impacted by the loss of one of our students,” the PTA’s Facebook page says. ” . . . No one is prepared to lose a child or other relative at such young ages.”

Beneath the post is a picture of Mariah, wearing glasses and braces and a shirt with hearts on it, smiling next to her grandmother.

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They met on a dating site and went bowling. It was a setup, police say, and now he’s dead.