A 14-year-old White Oak boy charged with killing his infant sister will be confined to a youth treatment facility, a Montgomery County judge said Tuesday.

During an April trial, the teenager was convicted of involuntary manslaughter and neglect of a minor, said Montgomery Circuit Judge David A. Boynton. Because he was tried as a juvenile, the trial was closed to the public.

The teenager was charged in February in the suffocation death of his 7-month-old sister, whom he had been caring for while their mother worked a night shift as a cleaner, police said at the time. The boy covered his sister’s mouth and nose with his hands to stop her cries, they said.

The eighth-grader — whom The Washington Post is not naming, because he is a minor — was not in court Tuesday. Mary Siegfried, his public defender, said he had asked to be excused from the hearing.

Juvenile-justice authorities recommended that the boy be removed from his home and placed in a secure facility where he would receive treatment, Boynton said. The state was waiting for space to open up.

“We need to hear back from the center when bed space will be available,” Boynton said. “Hopefully it won’t be more than a month or two.”

After the hearing, Siegfried said her client already has been undergoing “very intense counseling and therapy.” He could remain in treatment until he turns 21, when his case will be closed by law, she said.

“He’s doing great in a children’s care facility,” she said. “. . . He has no behavior issues.”

Prosecutors declined to comment after the hearing.

The morning of Feb. 8, Montgomery County Fire and Rescue workers were called to the teen’s White Oak home after his mother returned from her job at a local car dealership and found her daughter unresponsive, authorities said.

The mother had left her son in charge of the 7-month-old and her 3-year-old daughter the night before, according to police. She told police said that her son frequently cared for the infant.

But that night, something went wrong. After the defendant covered the baby’s mouth to quiet her, he walked her around the family’s apartment and then placed her in a car seat, according to documents.

The baby later died at Holy Cross Hospital in Silver Spring; the cause of death was later ruled asphyxia.

Police initially charged the boy with first-degree murder. In March, prosecutors reduced the charge to second-degree murder, moving the case into the juvenile system. In the end, he was convicted of an even lesser charge.

On Tuesday, the boy’s mother sat through the hearing quietly, surrounded by supporters, including her local priest. She declined to speak to reporters.

— The Gazette