Kevin Bui and the 2020 Green Valley Ranch Arson Murders
The Deadly Attack in Denver
Kevin Bui was the principal organizer of a revenge-motivated arson attack that killed five members of an innocent Senegalese family in Denver, Colorado. The fire was deliberately set during the early morning hours of August 5, 2020, at a residence located at 5312 Truckee Street in the Green Valley Ranch neighborhood. Bui was 16 years old when he carried out the attack with two teenage accomplices, Gavin Seymour and Dillon Siebert.
The victims had no known connection to Bui and had not participated in the robbery that motivated him. Bui targeted their residence after using a phone-location application to search for an iPhone that had been stolen from him. The application placed the device in the general vicinity of the Truckee Street home, but Bui incorrectly concluded that the people living at the house were responsible. Rather than reporting the location information to police and allowing investigators to determine who had the phone, Bui planned a retaliatory attack against the occupants.
The Events Leading to the Crime
In July 2020, approximately one month before the fire, Bui was robbed of his cellphone during an incident in Denver. Reports concerning the investigation indicated that he had been attempting to complete an illegal transaction when his iPhone and other property were taken. Bui subsequently used electronic tracking information to locate what he believed was the position of the stolen phone.
The tracking results directed Bui toward the Green Valley Ranch neighborhood. However, cellphone-location applications do not necessarily identify the precise building containing a device. Despite the uncertainty, Bui focused on 5312 Truckee Street and repeatedly researched the address. Investigators later alleged that he searched for the residence numerous times before the fire.
Bui recruited Gavin Seymour and Dillon Siebert to assist him. The three teenagers obtained masks and gasoline before traveling from the Lakewood area to the Denver residence. Their preparations demonstrated that the fire was not a spontaneous act. The group concealed their identities, transported an accelerant and approached an occupied home in the middle of the night, when the residents were likely to be asleep.
The August 5, 2020 Arson
During the early morning of August 5, Bui, Seymour and Siebert arrived near the Truckee Street house in a dark-colored sedan. Surveillance recordings showed three masked figures wearing dark clothing near the property. The perpetrators entered or approached the home, distributed gasoline inside and ignited the accelerant. They then fled as the fire rapidly spread through the residence.
The blaze erupted while several adults and children were sleeping. Flames and smoke blocked normal escape routes, leaving the occupants with little time to react. Five members of the Diol and Beye families were unable to escape and died from the effects of the fire and smoke. Two of those killed were very young children.
Three other residents survived by escaping through second-story windows. The survivors suffered injuries, including broken bones, as they fled the burning house. Their desperate escape emphasized the lethal conditions created by the intentionally set fire. The attack destroyed the home and devastated a family and immigrant community that had no involvement in Bui's stolen-phone dispute.
Victims of the Truckee Street Fire
- Djibril “Djiby” Diol, 29 — Killed on August 5, 2020, at 5312 Truckee Street in Denver, Colorado. Diol was a Senegalese immigrant, husband, father and civil engineer who had established a life with his family in Colorado.
- Adja Diol, 23 — Killed on August 5, 2020, at the Truckee Street residence. She was Djibril Diol’s wife and the mother of their young daughter, Khadija.
- Khadija Diol, 22 months old — Killed on August 5, 2020, inside her family’s Denver home. She was the daughter of Djibril and Adja Diol and was less than two years old.
- Hassan Diol, 25 — Killed on August 5, 2020, at 5312 Truckee Street. She was a relative of Djibril Diol and the mother of infant Hawa Beye.
- Hawa Beye, approximately 6 months old — Killed on August 5, 2020, in the fire. She was Hassan Diol’s infant daughter.
The Surviving Residents
Three occupants escaped the burning structure by jumping from upstairs windows. The survivors included members of another family living in the home, including a child. They sustained significant injuries during the escape but survived. The circumstances demonstrated that the perpetrators endangered everyone inside the residence, not merely the five people who died.
Because the fire was set while the house was occupied, prosecutors initially filed charges covering both the deaths and the attempted killings of the survivors. The original case against Bui included numerous allegations of first-degree murder, attempted murder, arson, burglary and related offenses.
The Initial Investigation
Investigators quickly determined that the blaze was suspicious. Surveillance footage from the neighborhood showed three masked individuals near the residence shortly before flames became visible. The figures fled in a four-door vehicle. Denver police released images of the suspects and appealed to the public for information, but the masks and dark clothing made immediate identification difficult.
The investigation continued for several months with few conventional leads. Detectives examined surveillance recordings, cellphone records, vehicle information, social-media communications and internet-search activity. Investigators eventually sought information concerning users who had searched online for the exact Truckee Street address during the period before the murders.
The digital evidence became a critical part of the case. Authorities discovered searches connected to Bui and identified links among Bui, Seymour and Siebert. Investigators also obtained communications relating to Bui’s stolen phone and his desire for revenge. A vehicle associated with the suspects was consistent with the car captured near the scene.
Arrests of Bui and His Accomplices
Kevin Bui, Gavin Seymour and Dillon Siebert were arrested on January 27, 2021, nearly six months after the fire. Bui and Seymour were prosecuted as adults despite being juveniles when the murders occurred. Siebert, the youngest member of the group, was handled through the juvenile system and Colorado’s Youthful Offender System.
Prosecutors characterized Bui as the driving force behind the attack. He was the person who had been robbed, identified the address, sought retaliation and enlisted the others. Although the three teenagers participated in the arson, the evidence indicated that Bui’s mistaken accusation and revenge plan set the crime in motion.
The Controversial Google Search Warrant
The case became nationally significant because investigators used a reverse-keyword search warrant to identify people who had searched for the victims’ address. Instead of requesting records belonging to a previously identified suspect, authorities asked Google to locate accounts that had searched for variations of the Truckee Street address during a defined period.
Defense attorneys argued that the warrant violated constitutional protections against unreasonable searches because police had requested information about initially unknown internet users. The dispute reached the Colorado Supreme Court. The court identified constitutional concerns with the warrant but allowed the evidence to remain in the case under the circumstances of the investigation.
The ruling permitted prosecutors to continue using the digital evidence that connected Bui and his accomplices to the address. The legal battle delayed the proceedings and contributed to the years that passed between the January 2021 arrests and the final resolutions of the cases.
Kevin Bui’s Guilty Plea
On May 17, 2024, Kevin Bui pleaded guilty to two counts of second-degree murder. One count represented the deaths of Djibril Diol, Adja Diol and their daughter, Khadija. The second count represented the deaths of Hassan Diol and her infant daughter, Hawa Beye.
Under the plea agreement, prosecutors dismissed approximately 60 additional charges, including first-degree murder, attempted murder, burglary and arson counts. The agreement called for consecutive 30-year prison terms, producing a total sentence of 60 years.
Members and representatives of the victims’ families had initially wanted the strongest possible punishment, but they ultimately supported the negotiated resolution. Bui had committed the crime as a juvenile, creating sentencing and parole issues that could have complicated a first-degree murder conviction. The plea ensured that he would receive a lengthy prison term without requiring the families to endure a prolonged trial and further appeals.
Sentencing
On July 2, 2024, Kevin Bui was sentenced to 60 years in prison for the five deaths. The sentence consisted of 30 years for each second-degree murder count, ordered to run consecutively. It was the longest sentence imposed on any of the three perpetrators.
The punishment reflected Bui’s central role in selecting the wrong residence and organizing the retaliatory attack. His decision to rely on imprecise cellphone-tracking information, assume the occupants were guilty and set fire to an occupied home resulted in the deaths of five innocent people.
Sentences for Gavin Seymour and Dillon Siebert
Gavin Seymour pleaded guilty to one count of second-degree murder and was sentenced in March 2024 to 40 years in prison. He acknowledged his role in the arson and expressed remorse during the court proceedings. Like Bui, Seymour was prosecuted as an adult.
Dillon Siebert pleaded guilty in juvenile court to second-degree murder. In 2023, he received a sentence totaling 10 years, beginning with three years in juvenile custody and followed by seven years in Colorado’s Youthful Offender System. His age at the time of the crime resulted in a substantially different legal process and sentence.
A Crime Based on a Fatal Mistake
The murders were not the result of any action by the Diol or Beye families. Police and prosecutors found no evidence that the victims had stolen Bui’s phone or participated in the robbery. They were targeted because Bui treated an approximate electronic location as proof and chose violence rather than contacting law enforcement.
The crime demonstrated the catastrophic consequences of revenge directed at an unverified target. Bui’s original grievance involved stolen property, but his response transformed that loss into a planned attack on a household containing multiple families and children. Five people died, three others were injured and an entire community was left to mourn.
Legacy of the Victims
The victims were members of Denver’s Senegalese community who had come to the United States to build stable futures for themselves and their children. Djibril Diol was remembered as a hardworking civil engineer devoted to his family. The deaths of Djibril, Adja, Khadija, Hassan and Hawa produced widespread grief in Colorado and Senegal.
Community organizations supported surviving relatives and assisted with funeral arrangements, housing and communication with prosecutors. Memorials and public statements emphasized the victims’ identities and accomplishments rather than the perpetrators. The case remains one of Denver’s most devastating modern acts of arson and mass murder.
Conclusion
Kevin Bui’s 2020 crime was a calculated arson attack founded on mistaken suspicion. After his phone was stolen, he identified the wrong Denver residence, recruited two friends, obtained disguises and gasoline and helped ignite a fire inside an occupied home. The resulting blaze killed five innocent family members, including a toddler and an infant, while three others narrowly escaped.
Years of investigation, digital-evidence litigation and court proceedings ended with guilty pleas from all three perpetrators. Bui, identified as the organizer, received a 60-year prison sentence in July 2024. The punishment resolved the criminal case, but it could not restore the lives of Djibril Diol, Adja Diol, Khadija Diol, Hassan Diol and Hawa Beye or erase the damage inflicted upon their surviving relatives and community.
