Cops: 15-Year-Old Boy Charged With Shooting To Death His 10-Year-Old Sister

A 15-year-old boy has been charged with the shooting death of his 10-year-old sister, authorities said Monday.

Izabella Heffernan was reported missing Sunday morning by her parents, who said she was last seen Saturday at 10 p.m. as she went to bed in the family's Bay County, Florida, home.

Read: Boy, 3, Accidentally Shoots Sister, 9, Dead With Great-Grandfather's Pistol

Authorities combed the area with dogs and an aerial search was conducted. Her body was discovered late that afternoon, wearing a sundress and covered by towels, according to a Bay County Sheriff's affidavit obtained by INSIDE EDITION.

Family members were questioned by Sheriff's detectives, the affidavit said. The brother, questioned with the permission of his father, told investigators he shot Izabella with his 22-caliber rifle, according to the document.

The boy gave conflicting explanations for the shooting, first saying he had mistaken her for a deer, and later saying he had been trying to teach her use his rifle when he accidentally shot her in the chest, the affidavit said.

"She starting making gurgling noises and I did not know exactly how to deal with that, so I shot her again," the document quotes him as saying.

Read: Family: Dad Shoots Twin Babies to Death in Their Mom's Arms Before Killing Her Father

Though he is named in the affidavit, INSIDE EDITION is not identifying the boy because he is a juvenile.

Major Tommy Ford told IE the teen is expected to be charged as an adult. He is currently being held at a juvenile detention center on an open murder charge, authorities said.

The boy told detectives where he had hidden his rifle and said he had changed his sister's clothes and moved her body to the clearing where her body was found, the affidavit said.

A motive for the killing was not released.

Watch: 6-Year-Old Reportedly Shoots Little Brother While Playing Cops and Robbers

Related Coverage