A 15-year-old boy accused of killing five members of his family called 911 and blamed the shooting on a 13-year-old brother he said had committed suicide.

But at the same time that call came in, his 11-year-old sister — who pretended to be dead after the boy shot her in the neck and hand — called 911 from a neighbor’s house and identified the older boy as the shooter, KIRO reported.

The mass murder took place early Monday morning in Fall City, a Washington state community east of Seattle, as CrimeOnline reported. Police said they received multiple 911 calls just before 5 a.m. — and an affidavit filed with the boy’s charges details those calls.

Investigators initially said they believed all the children involved were teens, but the investigation showed that only the shooter and the brother he tried to pin the murders on were teenagers. The other three children were 11, 9, and 7.

10242024_182813554-Information by kc wildmoon on Scribd

The court documents say the 15-year-old, who has not been named because of his age although his victims have all been named, was “out of breath” when he called 911 and said his 13-year-old brother “just shot my whole family and committed suicide too.” The boy said he was hiding in the bathroom and that his brother had been caught looking at pornography the night before and was in a lot of trouble.

While the older teen was blaming his younger brother for the slaughter, however, his 11-year-old sister — who described “holding her breath and playing dead” after the 15-year-old, whose face she saw clearly, shot her — escaped through a window and ran to the neighbor’s once she heard him leave the room and heard him talking to someone on the phone, presumably his fake 911 call.

The sister told investigators that the older boy had “gotten into a lot of trouble” after failing tests at school. She also told detectives that the 15-year-old was the only one of the five children who knew the combination to their father’s gun lockbox.  She said the boy used “her father’s silver Glock handgun” to kill her parents and siblings.

Police arrived and took the boy into custody. Upon arriving at the police station, attorneys told them the killer would not be speaking to them.

In the court documents, investigators say the boy “systematically murdered his family members — unknowingly failing to kill his 11-year-old sister — and then “staged the scene prior to the arrival of first responders to make it appear that his younger brother had committed the murders and then killed himself.”

The teen’s victims have been identified as Mark and Sarah Humiston, 43 and 42, and three of their children — 13-year-old Benjamin, 9-year-old Joshua, and 7-year-old Katheryn. All five were shot in the head.

The unnamed killer has been charged with five counts of aggravated murder and one count of attempted murder.

The 11-year-old girl remains hospitalized at Harborview Medical Center in Seattle, where she is in satisfactory condition.

According to CBS News, the accused murderer is being held at a juvenile detention facility and is to be arraigned on Friday. He is currently charged as a juvenile, and a judge will determine if the case “will be moved to an adult court.” The King County Prosecutor’s Office noted that  sentencing guidelines are different for juveniles even if they are tried in adult court.

The accused killer’s public defenders released a statement earlier this week saying the boy “is a 15-year-old boy who enjoys mountain biking and fishing and has no criminal history” prior to gunning down his entire family.

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[Featured image: Mark Humiston/LinkedIn and Sarah Humiston/Facebook]