The defense team for a 14-year-old DeKalb girl facing murder charges for stabbing her 2-year-old sister rejected a plea deal Wednesday that could have saved her from a sentence of life in prison if convicted.

While the teen’s mother asked Wednesday that a judge send the case back to juvenile court, prosecutors offered the chance at serving 10 years of a 20-year sentence if she pleaded guilty to voluntary manslaughter.

“I don’t think she should be tried as an adult and go to adult jail,” said a tearful Haneefa Ray, the mother of both the toddler and the teen.

DeKalb County Superior Court Judge Gregory A. Adams said he didn’t believe he had the discretion to send the case back to a juvenile court.

“We believe that reducing the charge from murder to manslaughter is a major concession,” said DeKalb County Assistant District Attorney Darius Pattillo.

Without the deal, Ty’Aisa Jackson could face life if convicted as an adult at trial early next year on murder, aggravated assault, making false statements and first-degree child cruelty charges for the Nov. 19 stabbing death of Sasha Lamaya Ray. (Though Jackson was 13 at the time of her arrest, The Atlanta Journal-Constitution is identifying her because she is being tried as an adult.)

On Wednesday afternoon, DeKalb County public defender Melanie Williams declined the reduced charges offer.

“The 20 to serve 10 is not consistent with what my client feels comfortable with, and certainly it isn’t consistent with what the mother and step-father of my client and the parents of the victim would like to see happen today,” Williams told Judge Adams.

Under the deal, the teen would remain in the Regional Youth Detention Center, where she has been since her November arrest, until her 17th birthday when she would be turned over to the custody of the state Department of Corrections. She would receive credit for all the time in custody since her arrest.

Had the defense agreed to the deal, Adams would have had the final say on sentencing. And he acknowledged that he wouldn’t follow Pattillo’s recommendation of 10 years in prison at this time.

“I will accept the reduction, but I will not commit to the sentence,” Adams said.

Pattillo said he pointed out to the teen’s mother and step-father that should the case go to trial, a guilty verdict would require 30 years of prison time before she could be eligible for parole.

But Adams countered, reiterating his refusal to abide by Pattillo’s recommended sentencing by suggesting that at trial he might give a jury the option of finding guilt on murder or a less serious charge.

“The reality of it is, if she’s found guilty of a lesser included offense, I don’t have to follow your recommendation, either,” Adams said. “Other than saying I’m not going to follow your recommendation, what else am I going to say?”

During the hearing, the teen cried as she heard prosecutors describe the wounds to her sister’s chest, stomach and defensive wounds on her hands.

“She stabbed her seven times,” Pattillo said. “The child suffered. The victim weighed 29 pounds and she fought for her life.”

Emory University psychology professor Dr. Eugene Emory provided a psychological assessment of the teen based on an interview with her.

“All of her awareness of what was totally going on was lost,” Emory told the judge. “There appeared to be some loosening of contact with reality.”

He said there were no indications that she would have another incident, were she provided with therapy.

From the witness stand, Haneefa Ray agreed with the psychologist.

“I think she just needs help,” the mother said.

In November, the then-13-year-old was watching Sasha and two other young siblings when she called her parents to report Sasha, the youngest, was missing.

The teen joined in the frantic search that eventually uncovered the toddler’s bloodied body in the backyard of the DeKalb County townhome, authorities said.

After a subsequent police investigation, the teen told her mother and step-father that she’d stabbed her younger sibling several times in the chest, step-father Shelton Ray told the AJC in November.