The trial for the third man accused of hurling large rocks at a string of cars, killing a 20-year-old woman and injuring several others in Jefferson County in 2023, was postponed Tuesday as a judge ordered he be mentally evaluated at a state-approved facility.
Joseph Koenig, who pleaded not guilty to first-degree murder in the death of Alexa Bartell, was set to begin his trial later this month. The delay comes as his defense attorneys requested to introduce additional witness testimony to the case from two experts on ADHD and late brain development — two conditions that could have affected Koenig’s decision-making before he and his two friends threw large landscaping rocks at oncoming traffic from a truck traveling at 80 mph, attorney Martin Stewart said.
Koenig, along with Nicholas “Mitch” Karol-Chik and Zachary Kwak, were charged shortly after the string of attacks, in which rocks narrowly missed the head of one driver and flung shattered glass into the eyes of others.
All three were 18 at the time. Karol-Chik and Kwak pleaded guilty to their charges earlier this year.
Prosecutors challenged the request, calling the defense “bogus” to a murder case while citing Koenig’s attorney’s late notice about concerns over his mental health condition less than three weeks before the trial was set to begin July 19.
First Judicial District Court Judge Christopher Zenisek acknowledged the frustration in timing, but ruled that the defense be allowed to introduce some of the testimony regarding Koenig’s mental state.
Impulsive behavior, brought by ADHD, or the characteristics of a juvenile brain between the ages of 18 to 20 could “decrease proof” that Koenig threw the rocks knowing he would create a grave risk of death, Zenisek said.
“Whether the jury accepts those things as facts is a different question,” he said. “But the court cannot sit here today and say that it is not relevant.”
Such as in other high-profile criminal cases, mental evaluations through the state hospital can cause severe delays. The mental evaluation for Koenig could take between eight weeks to eight months, Koenig’s defense attorney said, citing backlogs.
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The testimony and mental evaluation would ensure the trial was done right and reduce the possibility of an appeal, Zenisek said, but would also likely cause pain for Bartell’s and other victims’ families.
During a hearing last week, Koenig’s attorneys said testimony from an expert on the adolescent brain, psychological development and risk-taking, would be vital to the 19-year-old’s defense.
The testimony would provide the jury with information about how late adolescent brains work and how they can fail to perceive risks as an adult would, Stewart said, adding that research says brains could not be fully developed until as late as 25 years.
An expert who evaluated Koenig also found that he had executive functioning delays and ADHD, Stewart said.
Katherine Decker with the Jefferson County District Attorney’s Office said last week that the victims were “offended” by the late request, more than a year after Koenig was first charged in April 2023.
Decker also called defense’s request “absurd,” arguing there was “no good faith basis” for an ADHD defense to murder or testimony on late adolescent brain development that could be used for any defendant between the ages of 18 and 21.
“They cannot point to any authorities that allow either of these types of defenses: ADHD being a defense to murder or young adolescent brain being a defense to murder,” Decker said last week.
“Obviously, introducing a bogus defense to a jury is unfairly prejudicial to the people,” she added.
Koenig faces 19 counts, including first-degree murder with extreme indifference, and several attempted first-degree murder and second-degree assault charges, court records show.
A detective with the Jefferson County Sheriff’s Office testified in court last year that Koenig and his two friends were traveling at 80 mph when someone inside the car threw the 4-to-6-inch landscaping rock into Bartell’s car. After the attack, the driver turned around and all three men returned to her car stranded hundreds of feet off the road to take a photo as a memento. None called police before returning to their suburban Denver homes.
Police found Bartell, who had massive head trauma, slumped in the driver’s seat of her yellow Chevrolet Spark. In the road, police found a landscaping rock with her partial DNA on it.
Koenig’s next court appearance is scheduled for Aug. 23.