Attorneys representing a Fall City teenager charged with killing five members of his family say early accusations made by the prosecution led to damaging media coverage that continues to interfere with their ability to prepare for a key hearing in the case.
The 15-year-old, whose name is being withheld due to his age, is charged with five counts of aggravated first-degree murder and one count of attempted first-degree murder.
The charges stem from an Oct. 21, 2024, shooting that left his parents and three siblings dead, and his youngest sister seriously wounded.
A court hearing will determine whether the teen is tried in juvenile or adult court.
The King County Medical Examiner identified the victims as 43-year-old Mark Humiston, 42-year-old Sarah Humiston, 13-year-old Benjamin Humiston, 9-year-old Joshua Humiston, and 7-year-old Katheryn Humiston.
All five died from gunshot wounds to the head.
Prosecutors have described the killings as “aggressive, violent, premeditated, and willful.”
According to the prosecution’s summary of evidence, the teen allegedly retrieved his father’s Glock handgun and an extra loaded magazine from a case in the home, then returned downstairs to systematically murder his family.
After shooting his mother once, they say he broke down the bathroom door and shot her again.
Prosecutors say the teen then placed the weapon in his 13-year-old brother’s hand in an effort to stage the scene, took a shower, changed his clothes, and called 911 to report that his brother had killed the family and then himself.
Investigators later learned from a surviving sibling—who identified the 15-year-old as the shooter—that she had pretended to be dead after being shot in the neck and hand, then escaped to a neighbor’s home for help.
In a legal brief filed July 22, defense attorneys Kristen Gestaut and Amy Parker argued that their investigation has been significantly hampered by fallout from a November 2024 motion filed by prosecutors.
That motion accused the teen’s prior defense team—then with the King County Department of Public Defense—of tampering with or removing evidence from the family home.
Although the judge later ruled there was “no misconduct” and no violation of any court order, the defense says the allegations were widely reported and have had lasting consequences.
“The salacious details from the government’s slanderous motion were heavily reported on,” Gestaut wrote. “Anyone interested in the case, a witness to or otherwise involved in the case, or a potential juror in the case read and will forever have access to them.”
According to the defense, that publicity has led numerous potential witnesses—including family members, neighbors, and homeschool administrators—to refuse interviews or fail to respond altogether.
The defense also claims key individuals with information about the family’s home life have imposed restrictions on interviews or required prosecutors to be present.
They argue that the chilling effect created by the public allegations, combined with missing forensic reports and deleted digital evidence, makes it impossible to complete a fair and full evaluation under the eight Kent factors, which the court must consider before deciding whether to transfer the case to adult court.
Those factors include not just the severity of the crime, but also the teen’s mental and emotional development, background, and capacity for rehabilitation.
In contrast, prosecutors say the defense’s claims are exaggerated and that the team has not taken advantage of tools like court-ordered depositions to secure witness cooperation.
They also say the defense has failed to explain why interviewing 98 witnesses is necessary before moving forward with psychological evaluations, which are essential to the Kent process.
Prosecutors reiterated the brutality of the crime in a July 28 filing, calling the defense’s proposed timeline—pushing the decline hearing to October 2026—“plainly unreasonable.”
“There is no question that the respondent committed these crimes in an aggressive, violent, premeditated, and willful manner,” the state wrote. “After committing a sustained mass of violence... the respondent placed the handgun in his 13-year-old brother’s hand... took a shower and changed his clothing... and then reported to first responders that his brother was the one responsible for the nightmare they would find inside his home.”
The defense maintains the teen has no criminal history and had been considered a high-achieving student with strong community ties.
They argue that his background, emotional development, and the influence of a reportedly isolated and abusive household deserve careful evaluation before deciding whether he should face the rest of his life in adult prison.
A judge has not yet set a date for the decline hearing.
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