Teen Charged In Murder of Parents, 3 Siblings Tried Blaming Dead Brother and 'Staged' Scene: Police

Per court docs, the teen initially claimed his brother killed his family and committed suicide after getting caught looking at porn; his sister, however, survived by "playing dead" and told a different story.

A 15-year-old boy accused of murdering his two parents and three of his siblings initially tried pinning their deaths on his 13-year-old brother ... this according to new charging documents.

The incident went down earlier this week in Fall City, Washington, with police officially identifying the five victims as Sarah Humiston, 42, Mark Humiston, 43, and three of their children, Katheryn Humiston, 7, Joshua Humiston, 9, and Benjamin Humiston, 13.

The couple's 11-year-old daughter survived, as did her older brother -- the latter of whom is now accused of not only killing most of their family, but staging the scene to make it look like someone else did it.

Because he's a minor, the suspect's name has not been released.

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Per charging documents, via CBS News, the alleged shooter called 911 early Monday morning to say his 13-year-old brother "just shot my whole family and committed suicide too." He reportedly said he was hiding in the bathroom after his brother had "taken himself out." At some point, the suspect allegedly suggested a possible motive, saying his brother was caught looking a pornography the night before.

According to reports from the AP and KING 5, police received another 911 call minutes later from a neighbor, who said the 11-year-old sister showed up to their home with a gunshot wound. The sister reportedly said she saw the 15-year-old's face before being shot, then "described holding her breath and playing dead" until he walked away from her and she fled to a neighbor's home by escaping out a bedroom window. She reportedly identified the 15-year-old as the shooter -- and told authorities he had recently gotten in trouble for failing tests.

The sister reportedly told police she believed her father's Glock handgun was used, saying the 15-year-old suspect was the only one of the children who knew the combination to the lockbox. That Glock was allegedly found in the 13-year-old brother's hand, per police, leading them to believe the scene was "staged."

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Investigators said they believe the suspect "systematically murdered" his family, before he "then staged the scene prior to the arrival of first responders to make it appear" Benjamin, 13, committed the murders. "[The suspect] further perpetuated the false staging by repeatedly telling the 911 dispatcher that [Benjamin] was responsible for killing all their family and then committing suicide," per a statement of probable cause.

The 15-year-old brother was detained at the scene, while the sister was treated at the hospital and has since been released. On Thursday, the King County Prosecuting Attorney's Office announced the teen was charged with five counts of aggravated murder in the first degree and one count of attempted murder in the first degree with a firearm enhancement.

"In Washington State, anytime a 15-year-old is charged with aggravated first-degree murder, that's initially filed in juvenile court," they said in a statement. "However, prosecutors can ask a judge to move the case to adult court, although that is not the same as saying a 15-year-old is being tried as an adult because state law has different sentencing guidelines for juveniles in adult court."

Lafayette County Detention Center

"A case can only be moved to adult court with a judge's approval after hearing from prosecutors and defense," they added. "Based on the details in the charging documents, prosecutors are asking a judge for a hearing at which time both parties will present evidence and the judge will make the determination if the 15-year-old will be moved to adult court."

The Prosecutor's Attorney's Office explained that if the case remains in juvenile court, the teen "could only be held until age 25 — less than 10 years from now — with no further sanctions." If convicted in adult court, "the teen would be sentenced to 25 years to life with a statutory presumption of release after 25 years."

Earlier this week, the public defense attorneys told NPR, "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. Again, the law says our client is presumed innocent of these charges, and we are grateful for a judicial process that requires proof and evidence before there is a judgment."

He's scheduled to appear in court on Friday afternoon.

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