Gavin Seymour and the 2020 Denver House-Fire Murders
The Deadly Arson Attack
Gavin Seymour was one of three teenagers responsible for an intentionally set house fire that killed five members of a Senegalese immigrant family in Denver, Colorado, on August 5, 2020. Seymour and his accomplices, Kevin Bui and Dillon Siebert, targeted a residence at 5312 Truckee Street in Denver’s Green Valley Ranch neighborhood. The attack was carried out as an act of revenge after Bui mistakenly concluded that someone living at the house had stolen his cellphone.
The victims had no connection to the robbery that motivated the attack. Nevertheless, Seymour joined Bui and Siebert in preparing for and carrying out a nighttime arson at a home occupied by several adults and children. Seymour and Bui were both 16 years old at the time, while Siebert was 14. Their actions transformed a mistaken suspicion about a missing phone into the deliberate destruction of a family home and the deaths of five innocent people.
The Mistaken Revenge Plot
The plot began after Kevin Bui was robbed of his cellphone and other property during the summer of 2020. Bui attempted to locate the phone through an electronic tracking application. The location information appeared to direct him toward the Truckee Street residence, but cellphone-tracking technology does not always identify a precise building or individual. Investigators later determined that none of the people living in the house had participated in the robbery.
Instead of reporting the suspected location to police or attempting to verify who had the phone, Bui planned to retaliate against the residents. He recruited Seymour and Siebert to assist him. Authorities said the teenagers planned the attack in advance, obtained masks and gasoline, and researched the house before traveling to the neighborhood during the early morning hours of August 5.
The decision to attack the house was not the result of a sudden confrontation. The residents were asleep and had no warning that three masked teenagers were approaching their home. The perpetrators did not know the victims, and the family had been selected solely because electronic tracking information had placed the stolen phone somewhere near their address.
The Fire at 5312 Truckee Street
Shortly after 2:30 a.m. on August 5, 2020, Seymour, Bui and Siebert entered or approached the residence and used gasoline to ignite the structure. Investigators said an unlocked rear entrance allowed the attackers to gain access to the house. Gasoline was poured inside, including in the living area, creating a rapidly spreading and extremely dangerous fire.
Neighboring surveillance cameras recorded three masked figures near the residence and showed them fleeing as flames erupted from the house. Within moments, fire and heavy smoke spread through the interior. The attack occurred while the occupants were asleep, leaving them little time to understand what was happening or find a safe route outside.
The home was occupied by members of two related Senegalese families. Some residents were trapped by intense heat and smoke. Three people escaped by jumping from second-story windows, suffering serious injuries in the process. Five others, including two very young children, were unable to escape.
The Victims
- Djibril “Djiby” Diol — Age 29. Died on August 5, 2020, at the family residence at 5312 Truckee Street in Denver, Colorado. Diol was a civil engineer and the husband of Adja Diol. He attempted to escape the burning home with his wife and daughter but was overcome before they could reach safety.
- Adja Diol — Age 23. Died on August 5, 2020, at the Truckee Street residence. She was Djibril Diol’s wife and the mother of Khadija Diol.
- Khadija Diol — Age 22 months. Died on August 5, 2020, with her parents inside the Denver home. She was only weeks away from her second birthday.
- Hassan Diol — Age 25. Died on August 5, 2020, at the Truckee Street residence. She was Djibril Diol’s sister and the mother of infant Hawa Beye.
- Hawa Beye — Approximately six months old. Died on August 5, 2020, with her mother, Hassan Diol, inside the burning house.
The Survivors
Three members of another family living in the house survived by escaping through second-story windows. Amadou Sow awakened to smoke alarms and encountered a wall of heat and smoke when he attempted to leave his bedroom. With the normal exit route blocked, he jumped from a window and fractured his foot.
Sow’s wife, Hawa Ka, helped their 10-year-old daughter, Adama, escape through the window before jumping herself. Ka suffered serious spinal fractures in the fall. Their daughter survived without major physical injuries. The survivors were left to cope with their own injuries as well as the deaths of five relatives and the destruction of their home.
The Initial Investigation
Because the victims were Senegalese immigrants and Muslim, the attack initially raised fears that the fire might have been motivated by racial, ethnic or religious hatred. Investigators found no evidence that the perpetrators had selected the family because of their nationality or religion. The actual motive was eventually determined to be mistaken revenge connected to Bui’s stolen phone.
Detectives faced a difficult investigation. The masked figures captured on surveillance video could not be immediately identified, and the attackers had no known relationship with the victims. Investigators examined video recordings, telephone records, internet activity and location information in an effort to identify who had researched or traveled to the house.
A major breakthrough came from a search warrant seeking information from Google about users who had searched online for the address at 5312 Truckee Street during the days preceding the fire. Investigators learned that Bui had repeatedly searched for the residence. Additional cellphone and social-media evidence connected Bui with Seymour and Siebert and revealed communications about the robbery and planned retaliation.
Arrests and Criminal Charges
Gavin Seymour, Kevin Bui and Dillon Siebert were arrested on January 27, 2021, nearly six months after the murders. Seymour and Bui were prosecuted as adults. They initially faced numerous charges, including first-degree murder, attempted murder, burglary and arson. The charges reflected not only the five people who died but also the surviving occupants who had been placed in mortal danger.
The prosecution argued that the defendants knowingly participated in a planned attack on an occupied house. Although Bui was described as the leader of the revenge plot, Seymour voluntarily joined the preparations and went to the residence with the others. His age was considered during the legal proceedings, but prosecutors maintained that the number of victims and the calculated nature of the arson required a severe punishment.
Digital Evidence and the Legal Dispute
The investigation became nationally significant because of the warrant used to identify people who had searched for the victims’ address. Rather than requesting records for a suspect already known to police, investigators asked Google to identify accounts that had searched for variations of the Truckee Street address during a limited period before the murders.
Defense attorneys challenged the warrant, arguing that it amounted to an unconstitutional search of numerous internet users who were not suspected of a crime. The dispute reached the Colorado Supreme Court. In 2023, the court found constitutional problems with the warrant but allowed the evidence to be used because investigators had acted in good faith while relying on judicial authorization.
The ruling allowed prosecutors to retain important evidence linking the defendants to the address and the planning of the attack. The case became one of the most prominent examples of law enforcement using online search histories to solve a murder investigation.
Seymour’s Guilty Plea
In January 2024, Seymour pleaded guilty to one count of second-degree murder. Under the plea agreement, the remaining charges against him were dismissed, and the court was permitted to impose a sentence ranging from 16 to 40 years in prison. By pleading guilty, Seymour formally admitted criminal responsibility for his participation in the arson and the resulting deaths.
At his sentencing hearing on March 15, 2024, relatives of the victims described the permanent damage caused by the attack. Family members spoke about the loss of two generations, including an educated young father, two young mothers and two children who had barely begun their lives. Some relatives participated from Senegal and argued that no prison sentence could adequately account for five deaths.
Seymour apologized in court and said that he experienced guilt and remorse over his actions. He stated that he would prevent the crime if he could return to the night of the fire. The court nevertheless concluded that the severity of the offense justified the maximum punishment allowed under the plea agreement.
Forty-Year Prison Sentence
Seymour was sentenced to 40 years in prison for second-degree murder. The sentence was the maximum available under his plea agreement. The judge emphasized that the case involved a planned attack on an occupied home and the deaths of five innocent people, including a toddler and an infant.
The punishment also reflected the fact that Seymour had opportunities to withdraw from the plot before the gasoline was poured and the house was set on fire. He instead remained involved through the preparation and execution of the attack. His youth was considered, but it did not outweigh the consequences of his conduct.
The Sentences of Seymour’s Accomplices
Dillon Siebert, who was 14 at the time of the murders, pleaded guilty to second-degree murder. In February 2023, he was sentenced to three years in juvenile detention followed by seven years in Colorado’s Youthful Offender System. The agreement took into account his young age, his lesser role in planning the crime and his potential for rehabilitation.
Kevin Bui, identified by prosecutors as the organizer of the revenge plot, pleaded guilty in May 2024 to two counts of second-degree murder. On July 2, 2024, he was sentenced to 60 years in prison. Other charges, including first-degree murder, attempted murder, burglary and arson, were dismissed as part of his plea agreement.
A Crime Based on a False Assumption
The murders committed by Seymour and his accomplices were especially senseless because the victims had nothing to do with the theft that supposedly motivated the attack. A cellphone application pointed Bui toward a general location, but the teenagers treated that information as proof that the residents were responsible. They made no attempt to confirm the identity of the thief or determine whether the tracking information was accurate.
The perpetrators responded to an unverified suspicion with a deliberately planned arson at a house occupied by sleeping families. Their actions killed five people, seriously injured survivors and devastated Denver’s Senegalese community. What began as anger over a stolen phone ended in one of the deadliest residential arson attacks in Denver history.
Legacy of the Murders
The deaths of Djibril Diol, Adja Diol, Khadija Diol, Hassan Diol and Hawa Beye caused widespread grief in Colorado and Senegal. Community organizations raised money for the survivors and helped relatives travel, obtain housing and manage funeral arrangements. The murders also led members of Denver’s Senegalese and Muslim communities to reconsider security measures at their homes and community institutions.
Gavin Seymour’s case remains a stark example of how reckless retaliation, group participation and unverified digital information can produce catastrophic violence. Although Seymour expressed remorse and accepted a lengthy prison sentence, the consequences of the August 5, 2020, attack remain permanent. Five members of one extended family were killed because three teenagers chose to turn a mistaken electronic location into a target for revenge.
