JEFFERSON COUNTY, Colo. — After pleading not guilty to multiple charges earlier this year, the man accused of fatally shooting an Arvada police officer in September 2022 will face a jury trial beginning Tuesday morning.

Sonny Thomas Almanza III is accused of shooting and killing Arvada Officer Dillon Vakoff, 27, on Sept. 11, 2022.

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Almanza pleaded not guilty in late May to the charges against him, which include first-degree murder of a peace officer with extreme indifference, first-degree murder after deliberation, first-degree murder with extreme indifference, attempted first-degree murder after deliberation, and attempted first-degree murder with extreme indifference, among others.

The jury trial begins Tuesday and is slated to continue until Dec. 15. Tuesday will begin with jury selection.

What happened on Sept. 11, 2022 that led to the charges and Vakoff’s death?

Almanza, who was 31 years old at the time, told detectives after the shooting that he had recently separated from the children’s mother and while they did not have a court-issued child custody agreement, they relied on a mutual exchange, according to an arrest affidavit for Almanza.

Almanza told the detectives that on the evening of Sept. 10, 2022, she had the children. Early the next morning, while he was in downtown Denver, he learned that the children’s mother had left the kids with another family member.

At the time, he was with the woman who ultimately called 911 — who is referred to in this article as RP, or “reporting party” — and RP’s husband. RP is related to Almanza and lives in the same apartment complex as him.

The trio then drove to the home belonging to the mother’s mother, or the children’s grandmother. Almanza said he heard somebody crying inside, so he entered through an unlocked door and found the children in the care of juveniles, who were all family members of the children’s mother, according to the affidavit.

Almanza told detectives he took the children and headed home along with RP and RP’s husband, with RP at the wheel.

A short time afterward, the children’s mother texted and called Almanza with threatening messages that indicated “she and other members of her family were on their way to Arvada and were intending to begin an altercation with Sonny in order to receive (redacted),” according to the affidavit. Almanza told investigators he had been assaulted by members of her family in the past few weeks after they had broken up. He added that he knew some of her family were drug dealers and carried firearms, according to the affidavit.

Before they arrived at the apartment complex, the RP called 911 and reported that the mother of the two children was on her way to the apartment to try to take her children from Almanza. The RP told the 911 dispatcher she believed the mother was intoxicated.

Arvada Officer Dillon Vakoff and Officer D. Garibay began heading to the apartment, which was along the 6700 block of W. 51st Avenue, around 1:45 a.m. on Sept. 11, 2022.

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As the RP drove westbound on W. 51st Avenue approaching the apartment complex, the group saw several vehicles belonging to the mother’s family. Some people were outside their vehicles, Almanza told detectives.

RP’s husband stepped out of the car and was attacked, Almanza said, and when he got out of the car to help, he was involved in a fight for “only a few seconds” before he went to his apartment and retrieved his assault rifle, according to the affidavit. He noted that while he didn’t see if anybody was armed, he believed they had guns on them. The AR-15 he grabbed was a gift from RP’s husband and he told detectives he put the partially disassembled firearm together and went back outside.

At this point, Officers Vakoff and Garibay had arrived at the scene, which was described as a large, chaotic family disturbance, according to then-Arvada Police Chief Link Strate.

The two children remained in the car during the altercation and were not injured.

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Almanza fired the rifle one time into the air, began walking toward the fight and then saw the mother’s sister run toward him, according to the affidavit. The officers tried to separate the two groups, but when the sister was within 10 feet of Almanza — close to the car with the children inside — Almanza said he fired one shot at her and she moved to the curb and fell on the ground, according to the affidavit.

Strate said his officers tried to “separate several belligerent and uncooperative individuals” leading up to that shooting.

Almanza told detectives he didn’t see anybody else fighting, but thought altercations were still happening out of view so he walked around the outside of the building with the rifle’s barrel pointed up, according to the affidavit.

As he walked between two vehicles, he heard a gunshot and saw he had been struck on his right hip. He said he spotted a person north of him between two cars and fired one round, striking the person. He told detectives he did not realize the person was a police officer — Officer Vakoff — until the man fell to the ground, according to the affidavit.

Almanza threw the rifle in the backyard, according to an affidavit. He returned to the front of the building and was taken into custody. He claimed members of the mother’s family continued to assault and “drag him around” after he was in handcuffs, according to the affidavit.

Almanza, Vakoff and the mother’s sister were all transported to a hospital for their injuries. Vakoff died at the hospital.

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A detective said it appeared Vakoff had been shot in the head and the leg.

The sister, who was not seriously injured, told investigators she had learned that Almanza had taken the children, so she went to his home to retrieve them. She confirmed the fight began once Almanza, RP and RP’s husband arrived at the apartments, according to the affidavit.

Based on an investigation at the scene, police found that eight rounds had hit a wall behind where Vakoff was at the time of the shooting. Multiple rounds also damaged vehicles on either side of the officer, according to the affidavit.

Vakoff, who was 27 years old when he died, started with the department in 2019. Strate said Vakoff “is an example of everything that is good about a police officer.”

A procession transported Vakoff from Lutheran Hospital to the Jefferson County Coroner’s Office the morning of his death.

Vakoff was an Arvada resident and graduated from Ralston Valley High School in 2012. He was a staff sergeant in the U.S. Air Force where he served with the 96th Bomb Squadron for six years before joining the Arvada Police Department in 2019.

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Strate said Vakoff was training to be a SWAT officer and said he would have continued to have a positive impact on the department and community.

“This is a tragic loss to this community, to this department, but most significantly to his family and loved ones. His service and sacrifice will never be forgotten,” Strate said.