Who killed Tricia Westfall? Details explored as ID premieres American Monster

On November 15, 2021, Tricia Westfall, the 46-year-old mother and devoted public servant, wrapped up a day of work at the Arapahoe County Department of Motor Vehicles in Centennial, Colorado, anticipating a normal pickup by her husband. Instead, Tricia was repeatedly shot by her husband, Galen Wade Westfall, 57, within their moving car before he killed himself, causing a fatal accident.

The authorities promptly declared the accident a murder-suicide, with Tricia's cause of death as a homicide and Galen's as a suicide. The incident occurred in broad daylight, affecting passersby and leaving Tricia Westfall's family to cope with immense loss. As the facts come out, the case brings to the fore the secret risks of domestic violence, where jealousy and control spiral into lethal consequences.

Investigation Discovery's American Monster season 13 episode 1, titled Control Freak, airs on October 28, 2025, at 8 p.m. ET/PT on Investigation Discovery.

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American Monster: The background of Tricia Westfall and Galen's marriage

Galen shot Tricia Westfall several times (Image via Unsplash/ @ Ted Balmer)

Tricia Westfall was raised in Michigan as part of a family of five children, including a twin. She relocated to Colorado and established a secure professional career, spending more than nine years with the Douglas County and Arapahoe County DMVs. She was a single mother to two teenage boys from a previous marriage and had personal struggles, having lost an infant daughter several years previously, as per 9 News.

Galen Wade Westfall, 57 at the time of the offense, was a businessman and father of a teenage daughter from a previous relationship. The two married in 2009 after meeting in Colorado, combining their families in Castle Rock. The first few years of their marriage seemed solid, with Tricia's sons coming into the family along with Galen's daughter.

They lived together and shared daily habits, appearing to be a normal suburban family. But behind the scenes, tensions arose as Galen showed possessive tendencies, though no official reports of abuse were made to authorities during the period, according to the Colorado community media. The union lasted 12 years with joint responsibilities and occasional travel.

Tricia Westfall's family termed her as persistent and family-driven, with a tendency to always keep her children's interests at heart. Galen had a previous divorce, but the specifics were not revealed. Over the years, fights on trivial matters grew, paving the way for further confrontation. This period reflects how long-term relationships can mask growing incompatibilities, contributing to the volatility that ultimately defined their final moments, as 9 News reported.

The Arapahoe County Sheriff's Office later noted the domestic context without prior intervention records, underscoring gaps in early detection of relational red flags.

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Escalating tensions before the fatal day

Tricia Westfall was a victim of domestic violence (Image via Unsplash/ @ luca romano)

In the months leading to November 2021, Tricia Westfall and Galen's relationship showed signs of strain, centered on communication breakdowns and mutual frustrations. Family members observed frequent disagreements, often revolving around household dynamics and personal freedoms. Tricia's twin sister and sons recalled instances where Galen monitored Tricia's activities closely, though these were not escalated to police involvement.

The couple had recently returned from a family trip to Mexico, which highlighted underlying jealousies but did not prompt immediate changes, as per 9 News. On the morning of November 15, Galen dropped Tricia Westfall off at her workplace around 7:30 a.m., a routine act that belied the day's end. He then handled errands, including car maintenance, while Tricia performed her duties at the DMV.

Colleagues later reported her as focused and upbeat, unaware of any distress. Galen made several calls to Tricia Westfall as her shift ended, urging her to clock out precisely at 3:30 p.m. for pickup. This insistence aligned with his pattern of oversight, which the family described as increasingly rigid, as 9 News reported.

No external witnesses noted overt threats that day, but the sheriff's investigation revealed financial moves by Galen, such as account transfers, suggesting premeditation. Tricia's loved ones emphasized her forgiving nature, which may have delayed recognition of the severity.

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The incident: A deadly confrontation in motion

Galen killed Tricia Westfall in a moving truck [Image via Unsplash/ @ Ashwini Chaudhary(Monty)]

Tricia entered Galen's black Ford F-150 truck outside the Arapahoe County DMV at 3:30 p.m. on November 15, 2021. There was a quick escalation that ensued during their eastbound ride along Geddes Avenue in Centennial. There were reported possible shots heard by witnesses as the vehicle moved towards the intersection with South Havana Street.

The truck swerved suddenly, jumped the curb, and crashed into a stopped white pickup truck at 10700 E. Geddes Ave., stopping in a parking lot, according to Denver 7. Emergency personnel took minutes to arrive and locate Tricia and Galen dead within the cab of the vehicle. A handgun was found at the scene, and preliminary investigations suggested shots were fired while the vehicle was moving.

There was no evidence of brake utilization, further suggesting the impairment of the driver due to events. Passersby in other cars, including families, were hit by shrapnel but had only minor injuries, contributing to the chaos of the afternoon rush. The Arapahoe County Sheriff's Department cordoned off the scene, shutting down Geddes Avenue from Iola to Joliet streets for several hours.

The accident was recorded by surveillance cameras at area businesses, but the earlier argument was not. This timeline solidifies Galen as the killer, whose actions resulted directly in Tricia's death during the drive. The public nature of the incident stunned the neighborhood, turning a recognizable stretch of road into a tragedy site and inviting automatic calls for eyewitness testimony, as per 9 News.

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Investigation findings and family's path forward

Tricia Westfall's death was ruled as homicide (Image via Unsplash/ @ Markus Winkler)

After a quick investigation, the Arapahoe County Sheriff's Office determined that the deaths were a domestic-related murder-suicide on November 22, 2021. On November 17, autopsies performed by the Coroner's Office determined that Tricia had been a homicide victim and that she had died from multiple gunshot wounds to her upper body. On November 24, Galen's self-inflicted head wound confirmed his death as suicide.

After looking through phone logs, bank transactions, and vehicle information, detectives concluded that the shootings took place inside the truck while it was traveling. According to Denver 7, the case was closed as isolated since no additional suspects were found. Tricia's parents, twin sister, two sons, and other family members all provided full cooperation and shared their understanding of the dynamics of the couple.

In March 2022 interviews, they portrayed Tricia Westfall as a vibrant, supportive figure, a mother, aunt, and coworker who lit up rooms, as per 9 News. Her sons expressed grief over the sudden loss, vowing to honor her by raising awareness about domestic violence. The family joined broader advocacy efforts in Arapahoe County, where 2021 saw three similar intimate partner homicides. Galen's daughter received family support post-incident.

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Watch American Monsters season 13 episode 1, releasing on October 28, 2025, on Investigation Discovery.

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