The mental health expert nominated by the defense also said the boy could not be restored to competency within the time allowed by law, attorney Benjamin Brewer said this week.
The attorney declined to discuss the evaluation further. It wasn't made public, nor has an evaluation conducted by an expert nominated by prosecutors.
The boy, whose birthday was Monday, is accused of using a .22-caliber rifle to shoot his father and another man on Nov. 5 at the family home in St. Johns. Killed were Vincent Romero, 29, and a co-worker, 39-year-old Timothy Romans, who was renting a room.
The boy's competency is at the core of the case. The issue likely will be discussed at a hearing on a motion Brewer filed to suppress a police interview with the boy or during a competency hearing that could take place in January.
"That will be the biggest decision that will be made, for sure," he said.
If a judge finds the boy is incompetent and unable to be restored to competency within 240 days, the case could be dropped with prejudice, meaning it could not be refiled. Prosecutors are worried the boy never will get the treatment he needs and the victims never will see justice if that determination is made.
If the boy is found fit to stand trial, Apache County Superior Court Judge Michael Roca will hear arguments in a bench trial that attorneys say could wrap up by midyear.
Prosecutor Brad Carlyon said he expects the case to either go to trial or end with a plea deal by March or April, unless the boy is found incompetent with a chance of rehabilitation. That could delay the case by months while efforts are made to restore him to competency.
The next hearing in the case is scheduled for Jan. 6. The case has been on hold pending the results of the competency evaluations. Roca has said he believes it's inappropriate to rule on any substantive issues until the boy's competency is determined.
Brewer, who has advocated for the boy to be released from juvenile detention during the proceedings, said jail time should not be an option if the boy is found guilty or enters a plea.
"We would want probation," he said. "We would want no kind of incarceration, and we would want any kind of counseling that would be necessary."
The defense has challenged a warrant used to gather evidence at the home and the alleged confession. Brewer's motions and another by prosecutors to drop the murder charge stemming from Romero's death won't be ruled on if the boy is found incompetent.
Prosecutors have asked the state Court of Appeals to determine whether Roca can decline to rule on the motions. The court said it will consider the petition Jan. 13, which could delay the boy's case.