A Missouri judge ruled Wednesday that a 13-year-old boy who admitted shooting his mother and stepfather to death this summer should be held in juvenile custody indefinitely.

The teen's attorney said the admission came after the trial judge decided Wednesday not to allow him to be prosecuted as an adult. The attorney offered no motive for the shootings, but said the teen is sorry it happened.

The boy, whom The Associated Press is not naming because of his age, sat between his attorney and father during the afternoon-long hearing.

He was just 12 when the July shooting happened and has been in custody since then.

Law enforcement officers found the bodies of Rachel Duncan, 35, and Jaeson Duncan, 31, at their mobile home in Kaiser. The small central Missouri town is near the Lake of the Ozarks, about 45 miles southwest of the state Capitol in Jefferson City.

Jaeson Duncan was found near the front door, and Rachel Duncan in the main bedroom.

A Miller County sheriff's deputy who responded to the shootings testified Wednesday that he saw the teen coming out of the home and that the boy told him the shooter had fled.

Judge Kenneth Hayden ordered that the teen be committed to the state Division of Youth Services, which can keep custody over juveniles until they are 18 years old, but can petition the courts to extend that to 21 years old.

Under Missouri law, children as young as 12 can be charged as adults with first-degree murder.

Hayden acknowledged the seriousness of the killings, but said the teen is not mature for his age and had a chaotic home life.

"I sincerely believe that you can rehabilitated," the judge told the boy.

School officials testified that the boy had a few disciplinary problems including one fight.

Tammy Walden, chief juvenile officer for five counties including Miller, recommended the teen remain in juvenile custody.

A Department of Mental Health official told the court she believed the juvenile system is suited for the teen. Patricia Carter said the boy's chaotic living situation and past sexual abuse affected his development. She did not say who abused him.

Mandy McKinnon, the sister of Jaeson Duncan, told the court her brother was a good man who loved his family. She told the teen she is "very upset" he took away her loved one. She urged the boy to find God.

"I don't think you need a slap on the hands," she said.