The Teenage Family Annihilator

Why Would an Adolescent Want to Kill His Whole Family and Set His Brother Up to Take the Blame?

In Fall City, Washington, 25 miles east of Seattle, the Humiston family home sits along the wooded shores of Lake Alice. The 32-acre freshwater lake community, known for its rainbow trout and largemouth bass fishing, had seen no violent crime since the Humistons moved there in 2019. That changed at 5:00 AM on October 21, 2024. On that day, the entire Humiston family of six was almost erased.

Mark and Sarah Humiston

The first 911 call came from 15-year-old Andrew Humiston. He frantically told dispatch that he had locked himself in a bathroom on the main floor to protect himself from his 13-year-old brother Ben, who had murdered the rest of their family and then killed himself. Andrew told dispatch that Ben had been caught viewing pornography the previous evening and was facing punishment. He said he had waited ten to fifteen minutes after the last shots were fired to leave the bathroom and call for help.

Seven minutes later, a second 911 call contradicted his story. The Humistons' neighbor, Bradley Dennis, said that one of the Humiston's children, an eleven-year-old girl, had arrived at their door with a gunshot wound to her neck and hand. She identified Andrew - not Ben - as the shooter.

Crime Scene Analysis

First responders arrived at 5:12 AM. They first found forty-three-year-old Mark Humiston dead in the upstairs hallway with four gunshot wounds. In the main bathroom was forty-two-year-old Sarah Humiston with two gunshot wounds to her head; due to signs of forced injury, responding officers believe she had unsuccessfully attempted to barricade herself in. Nine-year-old Joshua and seven-year-old Katheryn lay in the hallway outside their bedrooms. Thirteen-year-old Ben's body was near the stairs, a Glock handgun in his left hand.

Detective Aaron Thompson's probable cause statement detailed multiple forensic inconsistencies in Anthony's story. The Glock in Ben's hand showed no signs of discharge - no gunshot residue on his hands, no ejected cartridges nearby. Blood spatter patterns on Ben's face and clothing indicated his fatal wound was inflicted from a distance and angle inconsistent with self-infliction. Most tellingly, the position of his body and the placement of the weapon appeared staged, with blood patterns showing the body had been moved after death.

The Survivor's Account

The eleven-year-old survivor slept in a top bunk, which gave her a clear view of events. It also probably saved her life. She described watching Andrew move methodically through the house, checking each victim's pulse and breathing. Her elevated position allowed her to see into the hallway while remaining partially concealed. When Andrew returned to her room, she held her breath and remained motionless; she played dead. The height of her bunk bed made it difficult for him to properly verify her vital signs, a factor that ultimately saved her life.

She provided crucial details about the sequence of events, describing how Andrew approached each victim, systematically moving through the house and carefully checking vital signs to make sure his victims were dead. Her account directly contradicted Andrew's story about their 13-year-old brother's actions and revealed the premeditated nature of the attacks.

Family Background

Property records show the Humistons purchased their home for $559,768 in 2019 after relocating from Texas. Following a lumber theft that year, they installed security cameras around the property. Mark Humiston worked as a senior software engineer at Hargis Engineers, where colleagues described him as a mentor who routinely helped newer employees navigate complex projects. Sarah Humiston had previously worked as a nurse, though, according to her state records, her license expired in 2023. The kids were being homeschooled.

No one in the family had a criminal record. The only documented legal issue was a 2023 civil dispute over property damage during a home remodel. Court records show the matter was settled within four months. Between the 2019 lumber theft and October 21, 2024, police received no calls to the residence.

Understanding Teen Familicide: Patterns and Psychology

It is rare for a teen to attempt to wipe out their entire family, so rare that I can't find any statistical data on how often it occurs. Parricide, the killing one or both parents, is more common but much less common than an adult child killing a mother or father. FBI data shows that approximately five parents are killed by their biological children each week in the United States; however, eighty-four percent of the matricide offenders and seventy-five percent of the patricide offenders are adults. On average, juveniles kill 31 fathers and 18 mothers per year.

Recent research reveals distinct patterns in how and why teens kill their families. Unlike adult family annihilators, who often act during financial crises or relationship breakdowns, teen perpetrators show unique behavioral and psychological patterns that develop over time.

The Path to Family Annihilation

Teens who attempt to eliminate their entire families typically begin planning months before their attacks. This planning often starts after what they perceive as irreparable damage to their status or future. In the Humiston case, Andrew's academic failures and subsequent parental confrontations created escalating tension. His sister later told investigators that he was the only sibling who knew the combination to their father's gun lockbox.

Common triggers for teen familicide include:

Academic Failure Impact: When teens face academic failure, the threat to their plans can trigger homicidal ideation. This often occurs in families with high academic expectations where college acceptance is considered mandatory. For example, a teen might begin planning family annihilation after realizing their grades will prevent college acceptance, seeing no way to meet family expectations.

Social Status Changes: Changes in social status or peer relationships can trigger planning. This might include social rejection, bullying, or loss of meaningful friendships. These teens often view their family as an extension of their damaged social status and decide to eliminate what they see as the source of their shame.

Family Restrictions: Severe limitations on autonomy can trigger homicidal planning. This includes restrictions on:

• Social media access

• Friend choices

• Dating relationships

• Extracurricular activities

• Technology use

• Personal freedom

The Distinction Between Parricide and Familicide

Teens who kill only their parents typically act in response to specific threats or circumstances. Recent research shows these attacks often occur after direct confrontations or revelations. For example, a teen might kill a parent who discovers drug use and threatens military school or attack after learning they'll be sent to a strict religious boarding school. These teens often act to eliminate what they see as a direct threat to their freedom or safety.

Parricide perpetrators frequently show evidence of:

• Previous physical abuse (documented in medical or school records)

• Prior calls to child protective services

• School reports of concerning home conditions

• Multiple runaway attempts

• Previous threats by parents of severe punishment or institutionalization

Teen familicide perpetrators, like Andrew Humiston, show markedly different patterns. Rather than reacting to specific threats, they often develop comprehensive plans to eliminate their entire family unit. The violence represents an attempt to erase what they see as a collectively shameful or restrictive family structure.

Planning and Execution Patterns

The systematic nature of teen familicide appears in several key areas:

Preparation Phase: Teens often spend months preparing for family annihilation, including:

• Learning family members' sleep patterns (when parents take sleep medication, which siblings wake easily)

• Studying home security systems (codes, camera locations, alarm patterns)

• Creating opportunities to access weapons (volunteering to clean guns, asking about security measures).

• Developing cover stories (like Andrew's story about his brother viewing pornography)

• Planning escape routes

• Establishing alibis (setting up activities or plans for the following day)

Execution Methods: Teen familicide perpetrators typically show methodical approaches. The Humiston case demonstrates several common patterns:

• Selecting early morning hours when victims are sleeping

• Moving through the house in a planned sequence

• Using multiple shots to ensure death

• Checking vital signs between attacks

• Managing potential escape routes

• Following a predetermined order of victims

False Narratives and Staging: These teens often create elaborate scenarios to deflect blame. Examples include:

• Staging crime scenes to suggest home invasions (breaking windows from inside, creating signs of forced entry)

• Making false 911 calls reporting intruders

• Planting evidence to implicate others

• Creating digital evidence of alternative scenarios

• Establishing false timelines through text messages or social media posts

Andrew Humiston's attempt to frame his deceased brother shows this pattern. His devious post-offense behavior included placing a gun in his thirteen-year-old brother's hand, making a preemptive 911 call, and creating a plausible motive (pornography discovery and pending consequences). Given the family's high religious reputation, his story seemed to fit the known family dynamics.

Warning Signs and Risk Assessment

Recent research identifies specific behavioral changes that often precede teen familicide:

Academic Changes

• A deterioration in academic performance

• Loss of interest in attending class or doing homework

• Skipping classes in patterns (certain days or times)

• Stopping homework completion while maintaining attendance

• Hiding academic reports or lying about grades

• Avoiding discussions of college or future plans

Social Behavior Changes

• Withdrawal from long-term friendships

• Increased isolation from family activities

• Changes in online activity patterns

• New interests in weapons or violence

• Unusual interest in family members' schedules

• Collecting information about family routines

High-Risk Warning Signs

Several behaviors require immediate intervention:

• Direct threats of family violence

• Attempts to acquire weapons

• Recording or documenting family activities

• Creating lists or plans involving family members

• Unusual interest in security systems or home layout

• Staging "practice runs" of security breaches

• Disclosing thoughts of killing family members to peers

Teen Family Annihilators versus Other Violent Teens

Recent forensic research reveals that teen family annihilators differ significantly from other violent juvenile offenders. They typically:

• Maintain higher academic and social functioning before the offense

• Show less evidence of prior violence

• Demonstrate more complex planning abilities

• Create more elaborate cover-up attempts

• Show higher levels of knowledge about family security and routines

The Humiston case exemplifies many of these patterns. Andrew maintained normal social functioning while planning the attacks, created a detailed false narrative, and demonstrated intimate knowledge of family security measures through his access to the gun safe.

Current Legal Status and Implications

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 tried as an adult, Andrew faces 25 years to life for each count of aggravated murder. His status hearing is currently set for January 8, 2025. He will remain in juvenile detention until then.

His sister has been released from Harborview Medical Center in Seattle following treatment for her neck wound. Andrew has been ordered to have no contact with her.

Conclusion

Life can take the hardest, darkest turn when we least expect it. No one who has spoken publicly about the Humistons thought this family was troubled. Was it different behind closed doors? It always is. I’m sure each member of this family could tell a different story about what living in this family was like. Just as my experience growing up in my family was different that that of my younger sister or brother.

I don’t know what story Andrew Humiston told himself to justify what he did, or what or what past he believed he had to erase. He knows he’s killed most of his family and robbed them of their futures. But he has also murdered his own. I’ve met many men behind bars who have spent decades paying for what they did in their teens or twenties. Humiston may not yet fully realize how his choices will shape his destiny and limit his future. But he will.