On October 21, 2024, at approximately 4:55 a.m., the King County Sheriff’s Office received a 911 call from a male who identified himself as Andrew Humiston, providing the address 7715 Lake Alice Road SE, located in the unincorporated area of Fall City, King County, Washington.

Humiston, sounding out of breath, told the 911 operator, “I just shot my whole family and committed suicide too.”

During the call, Humiston stated that his brother, referred to as BDH, had killed their family and “taken himself out,” while Humiston was hiding in a bathroom on the main floor of the house.

Humiston mentioned that a possible motive for BDH’s actions could be that BDH had been caught looking at pornography the night before and was anticipating serious trouble.

He said he called 911 approximately 10-15 minutes after the last shots were fired.

During Humiston’s 911 call, the Communications Center received a second 911 call from Bradley Dennis, who lives about a quarter-mile from the Humiston residence, at approximately 5:02 a.m.

Bradley reported that BAH, an 11-year-old sibling of Andrew Humiston, had arrived at his home, frantically ringing the doorbell. Bradley said BAH told him her family had been shot and that they were all dead.

He noted that BAH was injured with a possible gunshot wound, bleeding from her neck and hand.

The dispatcher asked if BAH knew who shot her family, and she responded that she heard gunshots and screaming, then saw Andrew Humiston’s face, identifying him as the one who shot her.

BAH described holding her breath and pretending to be dead. She also expressed concern that Andrew might come to the Dennis home to find her.

Bradley confirmed to the 911 dispatcher that Andrew was alive in the 7715 Lake Alice Road SE residence and might still be armed. Later in the call, when asked again if she was sure the shooter was Andrew Humiston, BAH confirmed it.

Deputies arrived at the residence and detained Andrew Humiston in the driveway. Upon clearing the home, deputies found the bodies of three individuals at the bottom of the stairs leading to the daylight basement living area.

These were later identified as 43-year-old Mark Humiston, 9-year-old Joshua Humiston, and 7-year-old Katheryn Humiston. Further down the hallway, deputies found the deceased body of a 13-year-old male, Benjamin Humiston.

In the master bedroom’s ensuite bathroom, they located the body of Sarah Humiston.

Andrew Humiston was taken to the Sammamish Police Station, where he was provided access to an attorney. His attorney informed detectives that Humiston would not speak to them. BAH, meanwhile, was transported to Harborview Medical Center for treatment.

Detective Ben Blakeman went to the hospital to arrange a forensic interview with her, conducted by Child Forensic Interviewer Layne with Det. Blakeman present.

During the interview, BAH identified her immediate family members: her father Mark, mother Sarah, and her siblings—Andrew, JCH, BDH, and KEH. When asked what happened, BAH became emotional and began to cry.

She explained that she and KEH shared a room, with BAH sleeping on the top bunk and KEH on the bottom. Early in the morning, they were awakened by gunshots. When BAH looked into the hallway, she saw her brother JCH and her father Mark lying on the floor.

She noticed blood on her father’s head and in JCH’s mouth. KEH, who had also woken up, entered the hallway, and BAH heard another gunshot, witnessing KEH collapse to the floor.

BAH then saw Andrew enter her room, point a gun at her, and shoot once or twice. She believed that one bullet hit both her hand and her neck, causing her immediate pain.

BAH recognized the gun Andrew used as her father’s silver Glock handgun. She recalled that Andrew was wearing a checkered shirt at the time.

During the incident, BAH heard someone yell “Stop” and “Help” and then the sound of what she thought was her father’s phone. She also heard Andrew speaking on the phone.

BAH saw Andrew leaning over the bodies in the hallway, appearing to check if they were alive by touching their necks or chests. Andrew then reentered her room, prompting her to close her eyes, hold her breath, and play dead as he stood next to her bed.

Eventually, she heard him leave the room and go upstairs, where he was again heard talking on the phone.

BAH used the fire window in her room to escape and ran to the street. As she passed the front of the home, she saw Andrew still talking on the phone near the entryway. She then ran to the nearby home of Karen and Bradley Dennis.

When asked about recent issues involving Andrew, BAH shared that he had been in trouble for failing tests at school. She mentioned that her father kept a Glock pistol in a small lockbox, which he sometimes placed by the front door to bring to work.

According to BAH, Andrew was the only one of the children who knew the combination to the lockbox.

After obtaining a judicially authorized search warrant, I conducted a walkthrough of the home. Near the main-floor entry, I observed a small, open gun lockbox and an empty pistol holster placed on a bench.

The hallway opened into a kitchen and dining area, with stairs leading to a loft/family room above and additional stairs leading down to a daylight basement with three bedrooms.

At the bottom of the stairs, to the left was a boys’ bedroom with a bunk bed and a single bed, attached to a bathroom. A black-and-white checkered shirt lay on the floor near the shower in the bathroom. In the hallway, I found JCH lying to my left with Mark partially covering JCH’s legs, and KEH slumped in the right-hand corner. Blood pooled heavily around all three.

To the right at the bottom of the stairs was the girls’ room with a bunk bed; blood was visible on the blanket and pillow on the top bunk. At the end of the hall, BDH lay on the floor, his head turned right and feet towards the master bedroom. BDH had an apparent bullet wound on his left cheek, with significant blood surrounding his head. A black Glock handgun was in his left hand resting on his chest, though no visible blood spatter was observed on his hand or the weapon.

In the master bedroom, I noted a substantial bloodstain on the carpet near the bed, with blood trailing into the en-suite bathroom. The bathroom door frame showed signs of damage, suggesting it had been locked and forcibly opened from the bedroom side. Blood-stained handprints marked the back of the bathroom door. A single fired 9mm shell casing lay in the bathroom sink, and near the toilet, Sarah’s body was folded forward in a large pool of blood. Additional shell casings were scattered throughout the lower-level hallway, with several fired projectiles found on the floor and one embedded in the wall at the end of the hall between the children’s rooms.

On October 22, 2024, autopsies were performed on three family members by forensic pathologists at the King County Medical Examiner’s Office, revealing the following results:

• Mark Humiston: Cause of death was multiple gunshot wounds, classified as homicide. Mark sustained four gunshot wounds: one grazing the left shoulder, one penetrating the left armpit, another to the lower right back, and one to the back of the head. Blood aspiration was noted in his lungs. Three projectiles were retrieved from his body during the autopsy.
• JCH (9-year-old male): Cause of death was a single gunshot wound to the forehead, classified as homicide. The bullet perforated his forehead, exiting at the back of his skull, and he had aspirated blood in his lungs.
• KEH (7-year-old female): Cause of death was a single gunshot wound across the top of her skull, classified as homicide. The projectile left a furrow across the bone, driving fragments into her brain, causing cerebral lacerations and brain hemorrhaging. She also had aspirated blood in her lungs.

On October 23, 2024, I attended the autopsies of Sarah and BDH at the medical examiner’s office, which revealed the following:

• Sarah: Cause of death was multiple gunshot wounds, classified as homicide. She sustained a perforating gunshot wound that entered behind her right ear and exited through her left cheek. A separate penetrating gunshot wound to her left eye/eyebrow area lodged inside her skull, where it was recovered during the autopsy.

BDH: Cause of death was multiple gunshot wounds, classified as homicide. BDH sustained a penetrating gunshot wound to his left cheek, with the bullet traveling from left to right at an upward angle through his brain and lodging in the upper right side of his skull. Chief Medical Examiner Dr. Lacy reported no evidence of scorching or stippling around this wound, indicating the shot was fired from a distance greater than 24 inches. BDH also had a second penetrating gunshot wound behind his right ear, with visible stippling on his ear, face, and scalp, suggesting the shot was fired from a distance of 6 to 24 inches.

Based on evidence from the crime scene, findings from the autopsy, and statements from BAH, it appears that Andrew Humiston systematically killed his mother, father, two brothers, and sister, and attempted to kill his other sister. He then allegedly staged the scene before first responders arrived to make it appear that BDH had committed the murders before taking his own life. Humiston further reinforced this false staging by repeatedly telling the 911 dispatcher that BDH was responsible for the killings and had committed suicide afterward.

Given these findings, I recommend charging Andrew J. Humiston with five counts of Aggravated Murder in the First Degree and one count of Attempted Murder in the First Degree.