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Alexa Bartell
Alexa Bartell

Three men charged in a deadly rock-throwing spree that killed a 20-year-old woman were linked to similar attacks in which rocks narrowly missed the head of one driver and flung shattered glass into the eyes of others, a lead detective alleged in court Wednesday. 

A string of attacks were detailed in a Jefferson County courtroom as prosecutors laid out the evidence against Nicholas “Mitch” Karol-Chik, Joseph Koenig and Zachary Kwak, who are accused of hurling 4-to-6-inch landscaping rocks at seven moving cars April 19 in Jefferson and Boulder counties, injuring several people and killing Alexa Bartell. 

A judge bound over all three men for trial at the end of the hearing. 

Lead detective Dan Manka, with the Jefferson County Sheriff’s Office, testified that the three men 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 hundred of feet off the road in a field to take a photo for a “memory sake.” None called police before returning to their suburban Denver homes, he said.

Bartell had massive head trauma and was 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, Manka said. 

Six other cars were struck before Bartell’s, Manka said, including one whose driver said the rock narrowly missed his head after plunging through his windshield near his line of sight. Three drivers reported they were injured with shattered glass lodged in their eyes, fingers and neck. 

The driver who was nearly hit in the head said if the rock was any higher, it would have killed him, Manka said. 

During an interview with police, Karol-Chik initially denied being involved but later admitted to encouraging his friends to throw rocks at moving vehicles and said he was concerned that he had done something that was going to ruin the rest of his life, Manka said. After seeing Bartell’s car, Karol-Chik said he “had a hint of guilt” and a “horrible gut feeling.” 

Kwak denied all involvement until an hour and 13 minutes into a police interrogation, according to a transcript presented in court. He later said to Manka: “I want to make it very clear that I did not kill that girl. I did not throw that rock. I don’t know what they told you, I don’t know what you think happened, I did not throw that rock,” according to court testimony. 

After striking Bartell’s car, Kwak told police there was “excitement” in the car, prompting Koenig to drive back to the field, Manka said. Kwak said he took a photo of Bartell’s car and later deleted it, but cellphone logs show his phone camera was used shortly after investigators believe Bartell was struck. 

Karol-Chik told investigators that he and two friends began throwing rocks at stationary vehicles before transitioning to moving cars. Karol-Chik said all three men hurled rocks while Koenig drove Karol-Chik’s truck.

He told police he felt he and his friends “took it too far” by throwing rocks at moving cars. The following morning, the three met at a Denny’s and Koenig said they “had to come up with a story” about what happened, Kwak said, according to Manka.

Koenig has refused to be interviewed by police. 

From left, Zachary Kwak, Nicholas “Mitch” Karol-Chik, and Joseph Koenig were arrested on suspicion of first-degree murder with extreme indifference after authorities say they threw a large rock at Alexa Bartell’s car, killing her April 19. (Photos provided by Jefferson County Sheriff’s Office)

During cross examination, defense attorneys argued that the estimated speed of a person’s car after being struck by an object is not always accurate and that traumatic events can warp one’s memory. No phone data was collected to determine how fast the victims’ cars were traveling when they were struck. 

The defense pointed out other gaps in the investigation, including missing information about the trajectory of the rocks and who threw the rock that struck Bartell or the six other cars April 19.  

There were conflicting stories about who threw the rock that killed Bartel, the testimony showed. Karol-Chik said Kwak threw it. Kwak said Koenig threw it. Aside from Bartell’s, no other DNA was found on the rock that plunged through her windshield, killing her. 

The men were arrested in their homes several days later after police reviewed cellphone data and spoke to a friend who had been hanging out with them earlier that day. 

The friend told police that Koenig liked to “cause chaos” and vandalize property. He said he asked to be driven home after he saw the three men collecting landscaping rocks from a Walmart parking lot and putting them into Karol-Chik’s truck because he had a bad feeling, Manka said. 

Karol-Chik told police he and Koenig had thrown rocks at cars at least 10 times before the April 19 rock-throwing spree, dating back to February, Manka said. 

Between learning of Bartell’s death and the day he was arrested, Kwak posted photos on social media of him going to prom and snowboarding, Manka said. 

“Even young adults such as these three defendants have common sense. We don’t need trajectory analysis or the exact weight of the rocks to know that (throwing) large landscaping rocks, or in one instance a large statue head, at oncoming drivers at high rates of speed would obviously create a grave risk of death,” Jefferson County Deputy District Attorney Morgan Fox said. 

All three teens face trial on charges of first-degree murder, attempted first-degree murder, second-degree assault and attempted second-degree assault. Karol-Chik and Koenig also face attempted first-degree murder and attempted second-degree assault for allegedly throwing a statue head at a moving car April 1 in Arvada. 

The men are next due in court in December, at which time a judge may set an arraignment date. 

Olivia Prentzel covers breaking news and a wide range of other important issues impacting Coloradans for The Colorado Sun, where she has been a staff writer since 2021. At The Sun, she has covered wildfires, criminal justice, the environment,...