Prosecutors are trying to bring the Fall City teen accused of killing his family to adult court

KING COUNTY, Wash. – The King County Prosecutor’s Office wants that move the case against a 15-year-old boy accused of killing his family to adult court.

The teen appeared in juvenile court Friday afternoon and prosecutors formally requested the case be moved to adult court, but a judge will ultimately decide whether that happens.

“That process takes months in all types of cases — the judge will have multiple opportunities to hear from prosecutors and the defense before making a final decision,” said Casey McNerthney, a KCPAO spokesperson.

A hearing to decide whether the case will go to adult court is scheduled for June 4, 2025.

On Thursday, the teen was charged with five counts of first-degree murder and one count of attempted murder.

Charging documents allege the teen shot all six of his family members in the early morning hours Monday at their home on Lake Alice Road near Fall City.

The King County Medical Examiner’s Office identified the shooting victims as Katheryn Humiston, 7, Joshua Humiston, 9, Benjamin Humiston, 13, and parents Mark Humiston, 43, and 42-year-old Sarah Humiston.

An 11-year-old girl survived the shooting and ran to a neighbor’s house for help after escaping out a window. According to a police report, the 11-year-old told police that her 15-year-old brother had killed the family.

The 15-year-old suspect went to another neighbor’s home and called 911, claiming his 13-year-old brother, Benjamin, had killed the family, according to charging documents.

Sheriff’s investigators allege the 15-year-old boy staged the crime scene and then tried to blame his brother for the shooting.

According to a sheriff’s report, the 15-year-old boy was the only child in the family who knew the combination to a key box for a Glock pistol kept in the family’s home.

Attorneys from the King County Department of Public Defense are representing the 15-year-old.

In a statement, attorney Amy Parker noted that the only evidence provided by the sheriff’s office and prosecutors is a 3.5-page affidavit of probable cause.

Given the media attention on this case and the seriousness of these charges, we want the court to know that we have been contacted by several people in the community who know our client and have testified to his good character. They describe him as friendly and caring. This is a boy who has many friends, pro-social interests and has made a positive contribution to his community. However, we are not working on the release yet. We want the court to know this information as the only information the court has at this time is the probable cause certification and charging documents.

Earlier this week, Judge Joe Campagna issued an order banning the media from releasing the 15-year-old’s name.

The decision whether to transfer the case to adult court will have major implications for the possible sentence, prosecutors said.

“If convicted of the charges in adult court, the state lawmakers’ sentence will be 25 years to life, with presumption of parole after 25 years,” McNerthney said. “The state’s Indeterminate Sentence Review Board will decide whether to release. If the case remains in juvenile court, the 15-year-old could only be held until age 25 – less than ten years from now – without further sanctions.”

The teen remains in secure custody at the King County Children and Family Justice Center.