The severity of a boy’s brain abnormalities and the senselessness of his crime will be deciding factors when a judge sentences a 15-year-old who committed a murder when he was just 12 years old.

Sharron "Tommy" Townsend pleaded guilty to second-degree murder in June, and now Circuit Judge Jack Schemer will decide how long the teen will serve in prison for killing 54-year-old Thomas Zona Trent in June 2014. On Wednesday, a sentencing hearing was held at which Townsend’s defense team highlighted his plight and prosecutors focused on his crime.

Townsend faces between 10 and 40 years behind bars. Schemer will announce the sentence at an undetermined date. The defense and prosecution are in agreement that Townsend could remain in the custody of the Department of Juvenile Justice until he is 21 so he can receive more intensive rehabilitation services, if the department and Department of Corrections agree.

Relying heavily on modern juvenile brain science, the defense used Wednesday’s hearing to try to show that Townsend, even from before the day he was born, was dealt a bad hand in life. Born to a mother who used drugs and alcohol during pregnancy, Townsend has had behavioral and learning issues his whole life, but never consistently received treatment even after he talked about suicide. S. Nicole Jamieson, Townsend’s attorney, called witnesses who testified to a history of abuse, homelessness and exposure to violence, but also adults in Townsend’s life now who could point to tangible ways the boy has grown and matured.

Prosecutor Alan Mizrahi, however, said he had a fundamental disagreement with what he called was the defense’s assertion that "life is predetermined." He argued that even Townsend’s witnesses were in direct conflict with one another: How could some say he had improved, while others said he was so damaged he couldn’t help what he did?

"The crux of the concept is that this child knew right from wrong and made the decision to act wrong," Mizrahi said. "While I agree that children may act differently (than adults), but they are not absolved from their actions."

The proceedings began Wednesday with the defense calling expert witnesses to testify to the causes of Townsend’s brain abnormalities and the extent to which they impact his ability to make rational decisions, resist impulsivity and understand what is happening around him.

Dr. Geoffrey Colino, a forensic neurologist in South Florida, testified via video conference that Townsend’s scans and records indicate a history of frontal lobe impairment consistent with a lack of impulse control. But, with 10 years of development still expected and the right combination of medication and behavioral modification, Colino said "absolutely" Townsend could improve.

"Unfortunately, he has yet to experience that kind of consistent care in his life," Colino said.

A second expert, Dr. Joseph Wu at the University of California Irvine, testified via video conference that Townsend’s brain scans are consistent with massive exposure to alcohol while in utero and maternal neglect in the early years of life. Wu, like Colino, also said with the right environment, Townsend could "bend the trajectory of his brain in an upward, positive direction."

But prosecutor Mizrahi and Colino sparred over Townsend’s brain defects and the causation of his criminal act.

"People with frontal lobe injuries have significant issues with impulse control," Colino said. "That is well documented."

But how does it make them shoot someone in the head? Mizrahi asked.

"That’s a very silly question," Colino said, adding that it doesn’t make a person act violently, but does cause difficulty in suppressing the urge should it arise. He added: "I will not be pulled into language I consider to be unscientific."

‘I shot somebody in the head’

The defense also called a teacher and a substance-abuse counselor who both described Townsend as a "model" client who shows leadership and initiative in their respective programs.

"He’s a joy," said Sally Crane, his literature teacher. "He’s a joy to have in our class. He’s eager to participate and engage. … He’s just a pleasure."

But during the state’s presentation, Mizrahi used Townsend’s own words to show a different side of the teen. Detective Eileen Simpson with the Jacksonville Sheriff’s Office explained the three different versions of events leading to Trent’s murder, as well as multiple Facebook messages Townsend had sent to friends saying he’d killed a man.

"I shot somebody in the head." "I killed the (white) man in 103." "I’m the one who killed the man on 103." Simpson and Mizrahi discussed at least a half-dozen messages in which Townsend admitted to the crime, which happened outside an abandoned hamburger restaurant on 103rd Street, where Trent, who was homeless, made his camp.

According to police reports, Trent owed Townsend money. Another homeless man interviewed by police said Townsend used to throw things at Trent and call him racist names and that Trent would say racist things back to him. Townsend is black and Trent was white. However, Townsend has not said definitively why he shot Trent.

Townsend’s case was the second in which former state attorney Angela Corey charged a young juvenile with murder, and it is one of the first high-profile juvenile cases to be settled under the Corey’s successor, Melissa Nelson. Nelson worked on the defense of Cristian Fernandez, the 12-year-old Corey charged as an adult with the first-degree murder of his toddler half-brother.

‘We were supposed to grow old together’

Several of the victim’s family members read or asked Mizrahi to read statements on their behalf. They described a loving man, a doting uncle and brother, who was voluntarily homeless but would still give coats and blankets to those in need.

Diana Trent, his sister-in-law, said she didn’t believe the science presented in Townsend’s defense took into consideration the pain her family has felt.

"We were supposed to grow old together as a family, but now we don’t have that choice," she said. "We just have old memories of him."

Dawn McNab, Thomas Trent’s older sister, said she’s not cold-hearted, but she wants Schemer to give the "maximum sentence allowable by law."

In a statement read by Mizrahi, Michael "Pete" Trent, Thomas’ brother, said Townsend knew what he was doing.

Townsend, speaking quickly and quietly, also read a statement. He said he wished he could go back and do things differently. He said he wants to be a better man, and show Trent’s family he’s not a bad person.

In apologizing to Trent’s family, Townsend said he wishes their loved one was "here for y’all because y’all seem like nice people."

Schemer will have to consider the seriousness of the crime, but also Townsend’s age and mitigating factors, including evidence of brain abnormalities presented by the defense. He will give the defense and prosecution at least a week’s notice before he announces his decision.

Tessa Duvall: (904) 359-4697