JEFFERSON COUNTY, Colo. — One of three defendants, charged with throwing a large landscaping rock that killed 20-year-old Alexa Bartell while she was driving in Jefferson County, was found guilty of all charges against him on Friday including murder in the first degree and multiple attempted murder charges.
Joseph Koenig was convicted on the first-degree murder charge in connection to Bartell’s death. The other charges were tied to other rock-throwing incidents involving other motorists around the same time.
This is the full list of charges on which Koenig was convicted.
- 1 count of first-degree murder
- 5 counts of attempt to commit first-degree murder
- 1 count of reckless endangerment
- 3 counts of third-degree assault
- 5 counts of attempt to commit third-degree assault
- 1 count of attempt to commit second-degree murder
- 1 count of attempt to commit third-degree murder
- 2 counts of attempt to commit reckless manslaughter
Alexa Bartell death: Man convicted of first-degree murder in JeffCo rock-throwing case
Koenig will be sentenced on Tuesday, June 3, 2025 at 8:30 a.m.
Bartell died on April 19, 2023 after Koenig threw the rock that crashed through her windshield as she was driving northbound on Indiana Street, just south of State Highway 128, in Jefferson County. His two co-defendants were in the car at the time. She had been on the phone with her friend at the time, who was worried when the line went silent and used the Find My iPhone app to find her friend. That friend drove out to her and when she saw Bartell’s serious injuries, she called Bartell’s mother and 911. Medical personnel at the scene pronounced Bartell deceased.
About a week afterward, three suspects were arrested. They were also accused of throwing rocks at multiple other cars.
All three defendants were 18 years old at the time. The men were all charged with first-degree murder, attempted murder, second-degree assault and attempted second-degree assault in connection with the 2023 death of Bartell.
Two of the men took plea deals. Zachary Kwak pleaded guilty to two counts of second-degree assault (causing injury with a deadly weapon) and criminal attempt to commit second-degree assault. Nicholas Karol-Chik pleaded guilty to second-degree murder, attempted first-degree murder and a crime of violence sentence enhancer added to the second-degree murder charge. All other charges against those two men were dropped.
The third man — Koenig — pleaded not guilty to first-degree murder, as well as multiple counts of attempted first-degree murder, second-degree assault and attempted second-degree assault in April 2024.
Denver7 covered every day of this trial. Read our previous coverage of the Joseph Koenig murder trial in the stories below:
Opening statements began on April 14. Prosecutors argued that Koenig’s actions that evening were “frequent, focused, and fatal,” while the defense said they do not dispute Koenig’s involvement in the rock-throwing incidents, but do not believe his actions warrant a murder charge. They urged the jury to find Koenig guilty instead of manslaughter.
Throughout the trial, the prosecution tried to prove that Koenig had been driving at the time, and throwing rocks “shot put style” with his left hand at oncoming drivers in the opposite lanes. Koenig’s defense attorneys called out previous interviews with the other two co-defendants, one of which said it had been Kwak who had thrown that rock.
In the middle of the trial, the prosecution brought up both Kwak and Karol-Chik, who were required to testify in the trial as part of their plea deals. While their testimonies had mismatching information, they both described what had happened on the night of April 19, 2023, from gathering the landscaping rocks to passing Bartell’s crashed car. Karol-Chik, a lifelong friend of Koenig, testified that he had lied during police interviews to protect his friend, and blamed Bartell’s death on Kwak, whom he barely knew.
“Joe said we won’t have to worry about it because we’ll just say that Zach did it,” Karol-Chik testified.
Nicholas Karol-Chik testified on April 18 that his close friend Joseph Koenig convinced him for some time after the incident to blame Alexa Bartell’s death on their other friend. Watch our coverage in the video player below.
Second co-defendant testifies against man on trial for murder of Alexa Bartell
Both Kwak and Karol-Chik testified that Koenig would speed up as they neared a car that night, and then one or more of the teens would throw a rock at the car. It started with stationary cars before they began throwing at moving vehicles. Kwak said he did not participate in the rock-throwing, which Karol-Chik disputed. After Koenig threw the rock at Bartell’s car, the teens passed by the scene several times before going home.
The co-defendants said Koenig seemed excited about hitting the car, but neither of them called for police or reported the crash out of fear of getting in trouble, they testified.
“There was concern in the car, but I couldn’t tell you if it was mostly for self or for her,” Kwak said.
Zachary Kwak, who already pleaded guilty, recalled an odd feeling in the car after they left the scene of Bartell’s crashed car. Hear more about his testimony in our April 17 report below.
Rock-throwing case: Co-defendant testifies in murder trial of Alexa Bartell
Closing arguments concluded Thursday morning and the judge gave the jury instructions. The jurors came back with their decision in less than 24 hours.
The decision comes less than a week after Bartell’s family marked two years since her death. For the past two years, they’ve scattered seeds, hoping to grow wildflowers across the roadside where her life was taken.
“She was a colorful light,” her mother, Kelly Bartell, said in an exclusive interview with Denver7 this week. “We want this horrific spot to be beautiful. Maybe other people will be able to look and see its beauty too. That’s another piece of Alexa we can spread.”
Family of Alexa Bartell honors her life two years after tragic death
To those who knew her, Bartell was more than just a victim of a random act of violence. She was a daughter, a niece, a friend — someone whose presence brought joy everywhere she went, her family said.
“We don’t want to just remember what happened,” Kelly Bartell said through tears. “I want to remember the 20 years of laughter, kindness, and love. That’s what we hold onto.”
Bartell’s compassionate heart, her deep loyalty, and her spontaneous joy live on in the stories her family shares: from insisting on holding the door open for strangers to encouraging her mom to help those in need.
