15-year-old accused of killing his parents and 3 siblings in their Washington state home (2024)

A 15-year-old boy accused of killing his parents and three siblings at their Washington state home shot them and then called police to falsely claim that his brother committed the slayings, according to court documents.

The 15-year-old, whom NBC News is not naming because of his age, was charged Thursday with five counts of murder and one count of attempted murder in the slayings Monday morning in Fall City.

Two adults and three children were found dead shortly before 5 a.m. Monday after a shooting was reported at a home in the Lake Alice Road neighborhood in Fall City, about 25 miles east of Seattle. The medical examiner's office identified them as Mark Humiston, 43, Sarah Humiston, 42, and their children Katheryn, 7, Joshua, 9, and Benjamin, 13.

An 11-year-old sister who was shot but survived by playing dead managed to escape through a window and went to a neighbor’s home, a King County sheriff’s detective wrote in an affidavit.

She was hospitalized and has been discharged, a spokesperson for Harborview Medical Center in Seattlesaid Thursday.

The 15-year-old boy was arrested the day of the shooting and was being held in a detention facility for juveniles Thursday.

The attempted murder count has a firearms enhancement, which allows for a greater sentence if the teen is convicted, the prosecuting attorney’s office said.

About 4:55 a.m. Monday, the 15-year-old called the King County Sheriff's Office and claimed that his 13-year-old brother had "just shot my whole family and committed suicide, too," a sheriff's detective wrote in a probable cause statement.

Investigators say that the claim is false and that the teen staged the scene to blame one of the victims, Detective Aaron Thompson wrote in the document.

The surviving 11-year-old sibling told police that her 15-year-old brother shot her and her family with a Glock handgun that belonged to their father, the probable cause statement says.

She told investigators that the teenager shot her and then left the room and that she heard someone shouting "stop" and "help" before she escaped, the detective wrote.

The surviving sibling told investigators that the handgun was kept in a lockbox and that the suspect was the only one of the children who knew the combination, according to the probable cause statement.

Amy Parker and Molly Campera, who are representing the 15-year-old, said Tuesday at his first court appearance that the “law presumes our client is innocent of these charges.” They called him “a 15-year-old boy who enjoys mountain biking and fishing and has no criminal history.”

“I would remind everyone that these are not proven facts, merely allegations, and the law presumes our client is innocent of these charges,” they said.

During Tuesday’s court appearance, the teen waived his right to appear and was ordered to have no contact with the surviving sibling.

Family members could not immediately be reached for comment.

In a court hearing Friday, prosecutors requested a hearing to determine if the case stays in juvenile court or if the suspect will be treated as an adult.

Defense attorneys filed a motion aimed at protecting the teen's privacy, and Judge Kristin Richardson granted it, in part, by deciding the minor suspect's name can't be published and he can't be filmed from the neck up, public defenders said.

Some of the counts had been filed with a designation that they are acts of domestic violence, the prosecuting attorney’s office said Thursday.

But Friday prosecutors amended four charges to remove domestic violence designations for three aggravated first-degree murder counts involving the suspects' siblings and the domestic violence designation in the attempted first-degree murder charge because state law prohibits those charges from moving forward, officials said.

A neighbor told NBC affiliate KING of Seattle that the couple home-schooled their children and that the kids were well-known and active in the community.

Mark Humiston was shot four times, and the mother had two gunshot wounds, according to the probable cause statement. The three children were also shot.

The evidence appeared to show that the suspect "systematically murdered his mother, father, two brothers, and sister, and attempted to murder his other sister," Thompson, the sheriff's detective, wrote in the probable cause statement.

The suspect "then staged the scene prior to the arrival of first responders" to make it appear that the 13-year-old victim committed the murders and died by suicide, the detective wrote.

King County Council member Sarah Perry called the shooting “a terrible situation.”

“My heart aches for the lives lost and all who are struggling to make sense of this loss right now,” she said on Facebook this week.

The teen's father worked as an electrical engineerfor Hargis Engineers, the company said.

“We are blindsided and saddened by the tragic events that have led to the loss of a respected colleague, mentor and friend, as well as the loss of immediate family members,” the company said in a statement. "Mark's leadership and vision were integral within our firm, and he will be greatly missed. Our thoughts are with his surviving family, friends, and colleagues during this difficult time.”

Minyvonne Burke

Minyvonne Burke is a senior breaking news reporter for NBC News.

Phil Helsel

Phil Helsel is a reporter for NBC News.

Antonio Planas

and

Christiana Corporon

contributed

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15-year-old accused of killing his parents and 3 siblings in their Washington state home (2024)
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