A jury Friday found a man accused of killing a Jefferson County woman by throwing a rock through her windshield in 2023 guilty of first-degree murder.
Joseph Koenig, 20, was on trial in the death of 20-year-old Alexa Bartell, along with several other crimes related to a weekslong rock-throwing spree.
The jury reached its verdict after deliberating for about seven hours, capping a 10-day trial in First Judicial District Court. First-degree murder carries a mandatory life sentence in Colorado.
The jury also found Koenig guilty on six attempted first-degree murder charges and attempted assault charges.
All three defendants in the case — Koenig, Nicholas “Mitch” Karol-Chik and Zachary Kwak — were 18 at the time of the crimes. Both Karol-Chik and Kwak took plea deals and testified during Koenig’s trial.
Koenig’s sentencing hearing was scheduled for June 3.
During her closing argument Thursday, Jefferson County Chief Deputy District Attorney Katharine Decker focused on three areas for the jury: frequent, focused and fatal. She recounted how Koenig and his friends went on repeated rock-throwing sprees over the course of several weeks, improving their aim through repetition.
“The defendant’s attacks were frequent, over and over and over …” she said, repeating the phrase. “The targets were focused, and all were on the driver’s side.”
On the night of Bartell’s death, Koenig was driving when he grabbed a 9-pound rock from the dashboard, sped up to at least 80 mph and then threw the rock “like a shot put out” out of the driver’s side window and into her windshield.
The rock slammed into Bartell’s head, killing her instantly and causing the car to veer off the road, down an embankment and through a fence before it came to a rest.
“You have the pictures of what that rock did to her,” Decker told jurors.
After the attack, a smiling Koenig “whooped” in excitement, then turned around at least twice to check on the crashed car.
That showed Koenig was “damn well aware” that rocks hurled from a car posed a “grave risk” of killing someone, satisfying the elements of first-degree murder, Decker said.
Under the law, Koenig can be convicted of murder regardless of whether the jury believes he threw the rock himself or was only complicit in the attacks, she said.
Defense attorney Martin Stuart said the evidence showed Koenig was not guilty of first-degree because he never believed his actions would harm anyone.
“What was going on in his head — what was his mental state? That’s what this case is about,” he said.
The night Bartell was killed, the three men were driving around and egging each other on through a series of escalating rock attacks, some at parked cars and some at passing motorists, according to Stuart’s account. But not until Bartell’s car veered from the road did they believe anyone had been injured.
“It never entered their minds that they were going to hurt let alone kill anybody,” Stuart said.
Stuart said even a court-appointed expert found that Koenig’s borderline personality disorder affected both his impulse control and his judgment, arguing his actions therefore fell short of the “culpable mental state” for murder.
Instead, the defense urged the jury to convict Koenig of manslaughter, a lesser offense that applies when someone “consciously disregards” a substantial and unjustifiable risk their actions could result in a death. Manslaughter normally carries a potential sentence of up to three years in prison.
“What Joe Koenig and those other two kids did were crimes,” Stuart said. “We’re asking you to find him guilty of what he did.”
Karol-Chik pleaded guilty to second-degree murder and attempted first-degree murder and faces between 35 and 72 years in prison. Kwak pleaded guilty to assault and attempted assault and faces between 20 and 32 years in prison.
Both are scheduled to be sentenced in early May.