Third guilty plea in 2020 arson that killed members of the Diol family

DENVER — The third and final suspect charged in the 2020 fire that killed five family members pleaded guilty Friday in Denver District Court — and will spend decades in prison under the plea deal.

Kevin Bui, now 20, pleaded guilty to two counts of second-degree murder. In exchange for the plea, 60 other charges were dismissed. A separate drug case Bui picked up in prison was also dismissed and resolved as part of the agreement.

As part of the plea deal, both sides agreed to a sentence of 30 years in prison before the Colorado Department of Corrections on each count, to be served consecutively for a total of 60 years. Formal sentencing is scheduled for July 2 at 9 a.m

Bui was the alleged mastermind of the plot to set fire to the Truckee Street house in the middle of the night – apparently in revenge for a stolen phone – but the wrong house was ultimately targeted.

Eight people were in the home when the fire was started in the early hours of August 5, 2020. The fire killed Djibril Diol, 29; Djibril’s wife Adja, 23; the couple’s two-year-old daughter, Khadija; Djibril’s sister Hassan, 25, and Hassan’s 6-month-old daughter Hawa Beye. A couple and their daughter survived the fire by jumping out of a second-story window.

On the morning of the fire, video surveillance from a neighboring home showed three people wearing hoodies and masks arriving at the home and then running away for about 10 minutes. About two minutes after they were seen running away, the house was engulfed in flames.

Bui, Gavin Seymour and Dillon Siebert were arrested in January 2021 after a months-long investigation. Seymour and Seibert had previously pleaded guilty for their involvement in the crime.

The suspects were arrested in January 2021 after months of investigation. This investigation revealed that Bui had been robbed a month earlier by someone who tried to buy a gun from him.

During that robbery, his phone, shoes and other items were stolen, according to previous court testimony.

Bui used an application on his iPad to locate his stolen phone, which was returned to 5312 Truckee St., at which point he planned to go there to retrieve his belongings, a detective testified. It turns out they were targeting the wrong house – and it didn’t belong to the person who robbed Bui.

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In January, Seymour pleaded guilty to second-degree murder in another case. In exchange for the plea, 60 other charges against him were dismissed. Those charges included multiple first-degree murder, attempted murder, assault and arson.

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A judge sentenced him in March to 40 years in the Department of Corrections.

Siebert pleaded guilty in December 2022 to second-degree murder and using a weapon in a crime of violence, which amounted to an extension of his sentence.

As an adult, he was sentenced to seven years in a juvenile correctional facility. He was also sentenced by a juvenile court to three years of service in the youth welfare department. After serving his youth sentence, he will serve his time in the juvenile corrections office.

Siebert also faces a suspended sentence of 26 years in the juvenile justice system, which he would only have to serve if he violates the terms of the seven-year sentence he is currently serving.

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