A 15-year-old boy in Fall City, Washington, was charged with killing almost his entire family Thursday after his attempt to frame his brother failed.

The boy, who has not been named, is accused of using his father’s Glock handgun to kill his parents, two younger brothers and one of his younger sisters on Monday. The dead were identified by the King County Medical Examiner’s Office as Mark Humiston, 43, Sarah Humiston, 42, Benjamin Humiston, 13, Joshua Humiston, 9, and Katheryn Humiston, 7. He also is accused of trying to kill his 11-year-old sister, who survived the shooting.

The boy called 911 at about 5 a.m. and told them that his 13-year-old brother, one of the victims, had killed his family members and then himself after getting in trouble for looking at pornography, according to court documents cited by The Associated Press.

The suspect’s 11-year-old sister, who was shot but then played dead, escaped through a window and went to a neighboring house.

The neighbor called 911 at the same time the suspect was on the phone and relayed the girl’s accusation that her 15-year-old brother had shot her family and shot her before her escape, according to the court documents, as cited by The Seattle Times.

The girl told investigators that her brother was the only one of the children who knew the code to open their father’s lockbox and that he had recently been in trouble at home for flunking tests in school. She was treated at the hospital and released, according to the AP.

Benjamin was found holding the Glock in his hand folded over his chest, but the medical examiner’s office determined that his gunshot wound came from more than 2 feet away, according to the Seattle Times.

The boy has been charged with five counts of aggravated first-degree murder and one count of attempted first-degree murder with a firearm enhancement and domestic violence designation. The charges were filed in juvenile court.

Under state law, he can be tried in adult court only after prosecutors ask for the case to be moved and a judge agrees after hearing evidence from both prosecutors and the defense.

“I would remind everyone that these are not proven facts, merely allegations, and the law presumes our client is innocent of these charges. We want the court to know that our client is a 15-year-old boy who enjoys mountain biking and fishing and has no criminal history,” defense attorney Amy Parker said in court Tuesday, according to Seattle NBC affiliate KING-TV.

• Brad Matthews can be reached at bmatthews@washingtontimes.com.