Family and friends of 20-year-old Alexa Bartell filled the seats of a Jefferson County courtroom Thursday morning, eagerly awaiting a jury’s decision on the fate of the man charged with killing her — Joseph Koenig.

Both the prosecution and defense made their final arguments to jurors in the first-degree murder trial of Koenig, 20, who is facing a litany of charges in the death of Bartell on April 19, 2023, and other rock-throwing incidents that caused damage and injuries to vehicles and motorists.

“Alexa Bartell’s silence is the sound that endures because Joseph Koenig was in the driver’s seat,” Deputy District Attorney Brynn Chase said. “This is murder.”

“What Joe Koenig and those other two kids did were crimes,” Koenig’s defense attorney, Martin Stuart agreed. But Stuart did not agree with the first-degree murder charge.

“We’re asking you to find him guilty of what he did,” Stuart said of the manslaughter charge the defense is asking for.

Koenig is accused of throwing a large landscaping rock from the driver’s side window of a speeding truck, striking Bartell’s windshield and instantly killing her near the 10600 block of Indiana Street near Rocky Flats Wildlife Refuge in Jefferson County that evening.

The defendant also faces various other charges — including attempted first-degree murder and second-degree assault — connected to three nights in which Koenig, along with co-defendants Zachary Kwak and Nicholas “Mitch” Karol-Chik, allegedly threw rocks at nine other moving vehicles and an array of parked cars, breaking various windshields and bumpers and even injuring three drivers.

All of the other victims were brought in by the prosecution to testify during the trial. 

Ultimately, the crux of the trial is whether or not Koenig acted with extreme indifference when throwing the rock from the truck. If Koenig acted with “complete disregard” for human life when throwing the rock, he would be found guilty of first-degree murder.

If, on the other hand, the jury finds that Koenig did not actively know that he may kill someone when throwing the rock, he would be found guilty of second-degree murder or manslaughter.

Defense attorneys brought in psychologists to talk about how adolescent brains aren’t developed enough, and that causes rash decisions without fully thinking through consequences.

The prosecution argued that Koenig acted recklessly, knowing that his actions — stretched across multiple evenings — could possibly result in the death of a victim.

Karol-Chik allegedly handed Koenig the 9-pound rock. According to Karol-Chik, who testified twice during the trial, Kwak told Koenig to speed up. Koenig then hit around 80 mph before tossing the rock at Bartell.

Chief Deputy District Attorney Katharine Decker argued that Koenig would obviously know the possible repercussions of the acts, especially after seeing smaller, soft-ball-sized rocks damaging nine other vehicles between February and April 19. 

“He saw the damage repeatedly. He saw the damage on just parked cars,” she told the jury Thursday morning.

She continued: “When you’re throwing large landscaping rocks at high speeds at an oncoming driver, one is creating a grave risk of death.”

Karol-Chik corroborated the idea during his testimony, saying: “When we were throwing rocks at oncoming vehicles, there was always the possibility that it could go through the windshield and hit someone.”

Kwak also mentioned the potential danger during his testimony, saying that he was uncomfortable with the rock-throwing because it “didn’t seem right to him.”

Both Karol-Chik and Kwak testified as a part of plea deals with the First Judicial District Attorney’s Office. The deals significantly lessoned both men’s charges from first-degree murder to second-degree murder and first-degree assault, respectively. 

The defense argued that the teens were just acting recklessly, committing pranks that escalated throughout the night — completely unaware of the potential danger.

“Whatever you may believe about those two kids, one thing they were consistent about from start to finish is that it never entered their minds that they could hurt people,” Stuart said.

Stuart added that all three of the defendants mentioned multiple times throughout interviews and testimonies that they were just targeting cars, not the people within them.

The jury will now have to decide on the charges against Koenig, which include:

• One count of first-degree murder for Bartell’s death.
• Nine counts of attempted first-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 second-degree assault for injuries suffered by three of those whose vehicles were hit by thrown objects.
• Six counts of attempted second-degree assault for other attacks in which the victims weren’t injured.

First Judicial District Judge Christopher Zenisek handed the case over to the jury around 12 p.m. Thursday for deliberations.