An Upper Providence teen has admitted that he accidentally killed his younger sister with his mother’s gun last spring.

Jah’sir Vasquez, 14, made the admission when he pleaded Friday to involuntary manslaughter during a hearing before County Court Judge Garrett D. Page. Vasquez, having entered the plea in juvenile court, is considered an adjudicated delinquent and will be sentenced in March after undergoing a psychiatric evaluation. He will remain under house arrest until then.

His attorney, Francis Genovese, said Monday that the plea was the most appropriate outcome for the case, which he called a “textbook example of involuntary manslaughter.”

Vasquez was initially charged as an adult with third-degree murder in the March killing of Jasiyah, his 12-year-old sister. But his former attorney, Carrie Allman, successfully petitioned the court to transfer his case to juvenile court, saying that the shooting was a tragic accident and that murder charges were not appropriate.

Jasiyah was shot when Vasquez was asked by his mother, Daisy Vasquez, to retrieve her handgun from her car parked outside the family’s apartment in the Collegeville area, according to the affidavit of probable cause for the teen’s arrest.

Surveillance footage recorded inside the home showed Vasquez raising the gun toward his sister, and it going off, the affidavit said. The girl was struck once in the chest, and was pronounced dead at the scene. Vasquez later told detectives that he didn’t want to hurt his sister, and that the gun accidentally discharged.

During Vasquez’s hearing last week, prosecutors said further review of the evidence supported Vasquez’s statement: There was no clip in the gun, only a single round in the chamber, and investigators say he believed the gun wasn’t loaded as he carried it inside.

As he awaits his disposition hearing, Vasquez has been instructed to have no contact with his mother, Daisy, who has a criminal case pending on endangering the welfare of children and reckless endangerment.

Prosecutors assert that Daisy Vasquez improperly allowed her underage son to handle her weapon on numerous occasions before the fatal shooting, and that she initially lied to detectives, claiming she was the one holding the gun when it went off and killed Jasiyah.