A Jefferson County jury found 20-year-old Joseph Koenig guilty of first-degree murder Friday in the death of 20-year-old Alexa Bartell two years ago this month.

Koenig was convicted after a two-week trial and about eight hours of deliberation by the jury of six men and six women on Thursday and Friday morning.

Bartell’s family — who filled court benches through the entirety of the trial — waited anxiously as the verdict was read. The family then burst into tears, clasping hands and hugging each other outside of the room.

Koenig stared forward, stone-faced, as the guilty verdicts were read of all 19 charges he faced. Deputies placed him in handcuffs and led him out of the room.

He did not look back at his family, who sat solemnly in the second row. They left quietly.

Koenig faces life in prison without the possibility of parole.

Along with the first-degree murder charge, Koenig was also found guilty of:

• Five counts of attempted first-degree murder and one count of attempted second-degree murder for other incidents in which rocks or other objects were thrown at oncoming cars on Feb. 25, 2023, April 1, 2023, and April 23, 2023 — the night Bartell died.

• Three counts of third-degree assault for injuries suffered by three of those whose vehicles were hit by thrown objects and six counts of attempted third-degree assault. 

• One count of reckless endangerment and two counts of attempted reckless manslaughter for other attacks in which the victims weren’t injured.

“Despite a conviction of murder in the first degree — extreme indifference — none of this ever had to happen,” Jefferson County District Attorney Alexis King said of the incident, which changed the lives of at least four people.

“It’s hard to be happy or feel satisfied that justice was served today,” Alexa Bartell’s mother, Kelly Bartell, said after the verdict. “It doesn’t fill what amazing life was lost. And three others were also lost and impacted.”

Bartell was driving to her girlfriend’s home after being at a friend’s house around 11 p.m. on April 19, 2023 when a landscaping rock smashed through her driver’s side window, immediately killing her and then exiting the rear window.

According to Koenig’s co-defendants — Zachary Kwak, 20, and Nicholas Karol-Chik, 20 — Koenig was driving Karol-Chik’s truck and shot-put a 9-lb. rock from the driver’s side window.

Koenig even sped up before throwing the rock, hitting around 80 mph, according to the testimonies of both Kwak and Karol-Chik during the trial.

The incident happened near the 10600 block of Indiana Street near Rocky Flats Wildlife Refuge.

As reflected in the charges, Bartell’s death was not the only time that Koenig and his former best friend Karol-Chik threw rocks from a moving vehicle at oncoming and parked cars.

According to the prosecution, led by Chief Deputy District Attorney Katharine Decker, Koenig and Karol-Chik threw rocks at 10 moving cars on three dates between February and January. All nine of the other victims testified during the trial — some suffering just vehicle damage, others hurt by flying debris from the rocks.

Kwak had joined the duo for the first time on April 19 after meeting them a few weeks prior, though Karol-Chik claimed he had thrown rocks with them before.

According to the co-defendants, the trio would whoop and cheer after striking the oncoming vehicles.

“He was excited,” Karol-Chik said of Koenig after the impact to Bartell’s car. “He kept turning from his seat to look at me and to look at Zach in the back seat. He would just look at us with his big smile on his face.”

Karol-Chik and Kwak’s testimony came as part of their plea deals with the First Judicial District Attorney’s Office last year.

Karol-Chik pleaded guilty to second-degree murder and attempted first-degree murder, facing a possible prison sentence between 35 and 72 years. Sentencing dates for the pair were pending the resolution of Koenig’s trial and their testimony against him.

Kwak pleaded guilty to first-degree assault, multiple counts of second-degree assault and attempted second-degree assault, with a prison sentence looming between 20 and 32 years.

Koenig, on the other hand, will face life in prison for the first-degree murder charge, with the sentences for the various other charges possibly being tacked on for him to serve at the same time.

The difference between Koenig’s conviction and the other lesser-included charges, such as manslaughter, was the overall intent of the actions leading up to Bartell’s death.

The crux of the question of his degree of guilt was whether or not Koenig acted with extreme indifference for human life when throwing rocks from the window that evening — the defining trait of first-degree murder along with pre-meditation.

Second-degree murder, while similar to first-degree murder, involves the intent to harm someone but inadvertently leading to their death.

Manslaughter, the charge Koenig’s defense fought for, is the act of recklessness inadvertently causing the death of another.

Koenig’s defense attorneys, Thomas Ward and Martin Stuart, tried to convince jurors throughout the trial that Koenig never attempted to hurt anyone when he threw the rocks. Instead, the trio was just pulling pranks they deemed harmless.

The defense attorneys also brought in psychologists to talk about how adolescent brains aren’t developed enough yet, and that causes them to make rash decisions without fully thinking through consequences.

The three were 18 at the time of Bartell’s death.

“We strongly believe that these three knew what they were doing,” Kelly Bartell said Friday afternoon.

The prosecution argued that Koenig’s actions were “frequent, focused and fatal,” according to Decker.

The group hit around 10 cars throughout the three nights, focused on targeted vehicles, and used rocks that could cause serious harm, Decker said in both opening and closing statements.

Decker also argued that the defendants knew the actions were dangerous, especially after seeing the damage the rocks did to parked vehicles before.

“When you’re throwing large landscaping rocks at high speeds at an oncoming driver, one is creating a grave risk of death,” she said during closing statements Thursday.

Koenig is scheduled to be sentenced on June 3.

The victory in court will not bring Alexa Bartell back, Kelly Bartell told the media after the verdict.

“This has been the hardest two years ever. We got justice today. I don’t know how to feel about it,” she said through tears. “I’m happy, but it doesn’t bring Alexa back.”

She added: “We don’t ever want this to happen again to anybody else. That’s been our main goal — to make sure justice is served.”