The fate of a New Mexico teenager who killed five family members in 2013 was in the hands of a judge Thursday after he heard differing opinions from medical experts.

Attorneys gave closing arguments in a lengthy hearing in children's court to determine whether Nehemiah Griego should be sentenced as a juvenile or an adult for killing his parents and three younger siblings at his family's home near Albuquerque when he was 15.

Griego, now 18, pleaded guilty in October to two counts of second-degree murder and three counts of child abuse resulting in death for killing his siblings — ages 9, 5 and 2.

Prosecutor Michelle Pato described the killings as predatory and cold-blooded, saying Griego shot his mother as she slept, then woke his younger brother to show him his mother's body before shooting the 9-year-old.

Griego took a photo of the two victims before shooting his younger sisters, Pato said, then waited for his father to get home to kill the former pastor.

Stephen Taylor, an attorney for Griego, told the judge that the teen grew up in a chaotic environment, suffered abuse from his father and likely received a traumatic brain injury.

Taylor also said the teen was diagnosed with schizoaffective disorder after his arrest and has made significant progress at a psychiatric treatment center for juveniles in the past year and a half.

Griego's counselors at the state-run center testified for the defense, saying the teen had matured into a role model for other troubled boys. One teacher described the teen as a thoughtful student despite having expressed racist viewpoints and a fascination with war and Nazi Germany.

Prosecutors called a California psychiatrist as an expert witness, who said Griego seemed "detached" during an interview last year. The teen offered a cold, matter-of-fact recounting of the rampage, Dr. Kris Mohandie testified.

Mohandie, who was the last to testify in the hearing Thursday, said he believed Griego had a mixed-personality disorder that would be difficult to treat.

A forensic psychologist for the defense said he recommended Griego receive five more years of treatment.