15-year-old charged with murder of parents, siblings near Fall City

A 15-year-old boy was charged Thursday with the murder of his parents and three of his siblings at a waterfront house south of Fall City.

King County prosecutors charged the boy in juvenile court with five counts of first-degree aggravated murder and one count of first-degree attempted murder for allegedly killing his family members and injuring his 11-year-old sister in their home by Lake Alice early Monday. Each of the six charges has a domestic violence designation.

The Seattle Times typically does not name juvenile suspects unless they are charged as adults.

According to documents filed in King County Superior Court on Thursday, the 15-year-old used his father’s Glock handgun.

The King County Medical Examiner’s Office identified the victims of the mass shooting as 43-year-old Mark Humiston, 42-year-old Sarah Humiston and three of their children: Katheryn Humiston, 7; Joshua Humiston, 9; and Benjamin Humiston, 13.

They all died from gunshot wounds, according to the Medical Examiner’s Office.

According to charging documents, the suspect called 911 shortly before 5 a.m. and reported his 13-year-old brother killed the family and then killed himself. The 15-year-old said he was hiding in the bathroom, according to the documents.

During that call, a neighbor also called 911, reporting the surviving 11-year-old sister ran to the neighbor’s house, rang the doorbell repeatedly, and told the neighbor her family members had been shot. The neighbor told the dispatcher the girl was bleeding from the neck and hand, and she had said she was afraid her 15-year-old brother might try to find her, according to the charging documents.

The 11-year-old girl told the neighbor she heard gunshots and screaming, then her 15-year-old brother shot at her, according to charges. She told the neighbor she played dead and held her breath.

Later, during the 911 call, the dispatcher asked if the girl was sure her 15-year-old brother was the shooter. She said yes, according to the charging documents.

When the 11-year-old was interviewed at Harborview Medical Center by investigators, she cried while describing being woken up by gunshots and seeing her brother and dad lying in the hallway with blood on them. Her sister had been sleeping in a bottom bunk below her and got up to go to the hallway when she was shot, according to the documents.

She saw her brother leaning over the bodies in the hallway and touching their necks to see if they were alive, according to the documents.

The 11-year-old girl said she used a window in her room to escape the home and ran, according to the charging documents. When she passed by the front of the house, she saw her 15-year-old brother talking on the phone. 

When investigators asked if her 15-year-old brother had issues at home, she said he had gotten into “a lot of trouble” for failing tests at school, according to the charging documents. 

The 11-year-old told investigators her father kept the Glock in a small lockbox that he would sometimes put by the front door. 

When King County sheriff’s deputies arrived at the home, they immediately detained the 15-year-old in the driveway and found the five dead people inside.

The 13-year-old boy, Benjamin, was found with a gunshot wound to the head and with the Glock in his left hand on his chest. However, the Medical Examiner’s Office determined he must have been shot by a gun further than 2 feet away, according to charges.

Mark Humiston had four gunshot wounds to the shoulder, armpit, lower back, and back of the head. 

Inside the home, investigators found the pistol holster and lockbox empty. The door frame of the bathroom, where Sarah Humiston was killed, was splintered as if it had been locked then forced open.

The suspect “then staged the scene prior to the arrival of first responders to make it appear that (his 13-year-old brother) had committed the murders,” a detective wrote.

The 15-year-old was put in touch with an attorney who told detectives he would not speak to them, according to the charging documents. He remains in King County’s youth jail at the Judge Patricia H. Clark Child and Family Justice Center. 

In filing the charges, the prosecutors also filed a motion seeking a “discretionary decline hearing,” in which they would make the argument that the juvenile court should decline jurisdiction and have the suspect tried as an adult — a process that could take months.

While 16- and 17-year-olds charged with murder and certain other serious violent offenses can be automatically charged as adults, a discretionary decline hearing is required before younger teens can be charged in adult court.

If convicted as charged in adult court, the teen would be sentenced to a minimum of 25 years.

The next court hearing is scheduled for 1:30 p.m. Friday.