Baltimore County father found guilty of murdering his son, attempted murder of infant daughter

After more than 20 hours of deliberations, a Baltimore County jury found Mark Jones Jr. guilty of shooting his young children and their mother.

Police said Jones shot and killed his 4-year-old son, Jacobi Jones, in Rosedale, Maryland, on Christmas Eve in 2024. His 1-year-old daughter, Peyton, and the children's mother were also shot.   

The jurors did not believe the shooting was premeditated and rejected first-degree murder and first-degree attempted murder charges. 

They found Jones guilty of second-degree murder and second-degree attempted murder, as well as several firearms charges and child abuse. 

Protecting Promyss

The children's mother, Promyss Marcelle, said she was disappointed the jury rejected the first-degree charges but she feels justice was ultimately served for her and her family. 

"I got justice for my son. I got justice for my daughter, and I got justice for myself," Marcelle told WJZ Investigator Mike Hellgren outside court moments after the verdict.

She said 4-year-old Jacobi would be proud. "Momma, you did it. Mommy, we did it. Stop crying, Momma, we did it," Marcelle said. 

His beaming smile is on the shirt she wore to hear the verdict. 

She and her mother thanked police, the prosecutors and doctors and nurses who provided crucial assistance in the case and during their darkest hours.

"Those nurses at Johns Hopkins who held me up, held my daughter up when she doesn't even know, they held her up when I thought she was about to lose her mind," Marcelle's mother said. 

Sentencing 

Jones' sentencing is set for September. 

Marcelle said she would like to see him spend the rest of his life in prison. 

His defense argued Marcelle was the possible shooter after a struggle for the gun, which was registered in his name. 

Jurors did not buy that. 

They declined to comment following their decision. 

Marcelle previously recounted how she called police about ten hours before the killing, but at that time, they told her they could not remove Jones from the home.

She has advice for women fearing domestic violence. 

"Leave. Call 911, and if you don't want to call 911 for some reason, reach out to TurnAround," Marcelle told Hellgren.

TurnAround is a nonprofit that helps victims of domestic violence in Baltimore City and Baltimore County. 

Marcelle also testified against Jones. 

Asked how she kept up her strength, she said, "God. My son. Prayers. Literally prayers."

Difficulty reaching a unanimous verdict

The jurors deliberated for nearly three days before arriving at their decision.

On Monday, jurors remained in the courthouse until they were dismissed around 10 p.m., after struggling to agree on a verdict. 

The first sign of trouble came when the jurors wrote the judge a note saying, "What happens if we can't all agree? A mistrial? We are getting nowhere in terms of agreement."

At some point during a marathon 12 hours of deliberations, the jurors asked, "If we come up with a verdict tonight, does that mean we don't have to come back tomorrow?"

The judge told them to keep working, and a unanimous verdict wasn't decided until Tuesday afternoon.

Deliberations started on Friday, June 26, continued through Monday, and finally ended on Tuesday.

Recap of the trial

During closing arguments, prosecutors detailed a "toxic relationship" between the parents. They argued the parents exchanged texts, and the mother, Promyss Marcelle, said she wanted Jones gone.

"I'm begging you to leave my apartment," Marcelle wrote in one text. "I don't want you here."

Jones said, "I don't have to leave." 

Marcelle sent more texts pleading with Jones to leave, with no success on Christmas Eve morning in 2024.

In Jones' final text before the shooting, he wrote to Marcelle, "When you stop the child support, I'll leave."

Marcelle responded, "I'm never stopping it."

Prosecutors said Jones went into the bedroom of the apartment where Marcelle and their two children were staying, and opened fire with a gun registered in his name. Jacobi Jones was shot in the head and killed, while Marcelle and their 1-year-old survived the shooting.

Jones' defense attorneys argued there was a struggle for the weapon and said Marcelle may have pulled the trigger. The defense attorney said police automatically assumed her client was the suspect from the start.

Jurors also heard testimony from detectives and medical examiners, and saw photos and videos of the crime scene.