Missouri Man Charged with First-Degree Murder After Mother of His Child Found with Plastic Bag Over Her Head

A man is facing serious charges related to a 2021 crime in St. Louis.

ST. LOUIS, MISSOURI- A Missouri man is behind bars facing a first-degree murder charge in the gruesome 2021 death of Alvatyne Thomas, the mother of his child, who was found bound, mutilated, and executed in her own home with a plastic bag taped around her head.

Karl Mayberry, 34, was arrested on Wednesday following a lengthy investigation and has been formally charged in connection with Thomas’ brutal killing, according to court documents reviewed by Law & Crime. Authorities say forensic evidence, digital communications, and damning behavior after the murder all point to Mayberry as the suspect in what investigators described as a calculated and violent crime.

On December 27, 2021, officers from the St. Louis Metropolitan Police Department responded to a welfare check at a residence in the 4000 block of Oregon Avenue. Upon entering the home, officers discovered 31-year-old Alvatyne Thomas sitting upright in a chair, deceased, with a plastic bag taped over her head.

The probable cause affidavit outlines disturbing details of the scene:

• Thomas had been shot in the back.

• Her forehead was swollen, and one ear was severed.

• Investigators noted defensive wounds on her hands, suggesting a struggle.

• Her body had bleach poured over it, an apparent attempt to destroy evidence.

According to family members, Thomas had been in an abusive relationship with Mayberry, the father of her child. Police obtained and examined Thomas' cellphone, which showed she had been texting with Mayberry shortly before her death. In one of her final messages, she told him she was home and about to go to sleep.

Mayberry told investigators he was at work during the timeframe of Thomas' murder. However, coworkers contradicted his alibi, telling police that Mayberry disappeared for hours and returned wearing different clothes, visibly upset.

A search warrant for Mayberry’s cellphone and social media accounts revealed messages he sent immediately after the murder. In one message to another person, Mayberry described Thomas being found with a plastic bag around her head—a detail police had not yet released publicly.

Authorities also discovered incriminating search history, including:

• “First degree murder defenses”

• “Can he say she says be used against a person for murder in Missouri?”

• A text to a defense attorney inquiring how much it would cost “to defend a murder”

These digital breadcrumbs, combined with contradicting statements and forensic findings, led to Mayberry’s arrest.

At the time of Thomas’ death, Mayberry was on federal probation for prior convictions, including felony assault and being a felon in possession of a firearm. He was booked into the St. Louis City Justice Center and is being held without bond.

Mayberry made his initial court appearance on Friday afternoon and is now awaiting further legal proceedings. Prosecutors have not yet announced whether they will seek life imprisonment or the death penalty if he is convicted.

Thomas’ murder and the years-long investigation have reignited local concerns over domestic violence and system failures in protecting women with documented abuse histories. Loved ones say they repeatedly warned Thomas was in danger.

This case serves as a harrowing reminder of how domestic violence can escalate to fatal consequences—and how abusers often attempt to silence and erase their victims with brutal precision.