Authorities say a 15-year-old girl who was repeatedly locked in her room with just a blanket and a bucket fatally shot her 16-year-old brother this week in White Springs, Fla.

Police say the 16-year-old boy locked his sister in her room on Monday while their parents were out of town. After he fell asleep, the 15-year-old allegedly talked her 11-year-old sister into unlocking the door.

Police say the teen girl then broke into her parents' room through a window and used their pistol to fatally shoot her brother.

The teen girl had endured years of abuse, police say. According to police documents, their mother reported that they often locked their 15-year-old in her room, and their father said they had done so for up to 20 days straight. The room that they kept her in contained a blanket and a bucket filled with urine, police reported.

In 2010, the teen girl's uncle was convicted of molesting her. Then, in 2011, the girl's mother reportedly caught the siblings having sex. The teen girl had also tried to commit suicide in the past, but it was not reported to authorities.

Prosecutors are mulling whether to charge the 15-year-old girl and her 11-year-old sister as adults. Their parents also face child neglect charges.