Jury Begins Deliberations in Trial of Father Accused of Killing Son

Jurors began deliberating Friday afternoon in the trial of a Baltimore County father accused of fatally shooting his 4-year-old son and wounding his 1-year-old daughter and the children's mother.

Mark C. Jones Jr., 31, is charged with first-degree murder, two counts of first-degree child abuse, two counts of attempted murder, two counts of first-degree assault and multiple weapons offenses.

If convicted, prosecutors intend to seek a sentence of life without the possibility of parole, according to court records.

Prosecutors allege that Jones and Promyss Marcelle had a toxic relationship that led Jones to shoot her, their two children and himself shortly after 6:30 a.m. on Christmas Eve 2024 inside an apartment on Breslin Court in Rosedale. Their 4-year-old son, Jacobi, died from a gunshot wound to the head.

“This relationship was based on power,” said prosecutor Madison Frank, “who has it and who doesn't.”

Marcelle testified that she and Jones had argued throughout the previous night about child support. On Christmas Eve morning, she said, Jones loaded a handgun and said, "We are all dying tonight.”

Marcelle had sent Jones text messages that morning pleading with him to leave the apartment. Investigators allege Jones retrieved a handgun from a backpack and opened fire as Marcelle and the children were on her bed.

The 1-year-old girl was shot in the shoulder, and Marcelle was shot in the back of the head. Jones sustained a gunshot wound to the jaw.

Jones did not testify, and the defense called no witnesses.

Defense attorneys argued that investigators prematurely concluded Jones was responsible and built the case around that assumption rather than conducting a complete investigation.

"You have the State handing you this mess of a case and they want to tell you, 'Figure it out,'" defense attorney Erin Cullinan told jurors during closing arguments. She argued that Marcelle's account was inconsistent with the physical evidence presented during the trial.

The defense portrayed Marcelle as a woman determined to force Jones out of her apartment. Attorneys introduced text messages from months before the shooting in which Marcelle said she hoped Jones would die. They also pointed to statements Jones made to emergency personnel at the scene claiming Marcelle had shot him. Jones also said the two had "tussled" over the 9 mm handgun.

The shooting occurred hours after Marcelle called police to report a domestic dispute.

The couple had been in an on-and-off relationship since 2019, Marcelle testified. He’d recently moved back in and she had asked officers to remove Jones from the apartment the night before the shooting. Finding no evidence of an assault, officers instructed the two to stay in separate rooms and explained how to obtain peace orders.

According to Marcelle, the argument resumed the following morning. From her hospital bed, she told detectives that Jones had asked Jacobi whether he wanted his father to leave. The boy, she said, said yes.

Officers found Jones bleeding from the face on the bedroom floor. His speech was difficult to understand because of injuries to his jaw. A surgeon later removed bullet fragments from his mouth.

Jones was on a FaceTime call with his mother when officers arrived. In closing arguments, Deputy State's Attorney Lisa Dever noted that Jones never called 911 to summon help for himself or his children. Instead, Marcelle ran to an upstairs neighbor's apartment to seek help and call 911.

Jurors began deliberating around 3:30 pm Friday.