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Three men accused of hurling large rocks at several cars west of Denver last week, killing a 20-year-old woman, drove back to take a picture of her car after the fatal crash, arrest documents show.

“We have to go back and see that,” one man said to his two friends after a landscaping rock smashed through Alexa Bartell’s window, striking her in the head and killing her April 19, according to an arrest affidavit. 

One of the suspects told police he felt a “hint of guilt,” but that all three were excited when the rocks they threw hit a car. He and another man suspected in the rock-throwing spree had been throwing rocks at cars on at least 10 occasions since February.

Joseph Koenig, Nicholas “Mitch” Karol-Chik and Zachary Kwak, all 18, face first-degree murder charges. Authorities say the men acted with “extreme indifference,” meaning they knowingly created a “grave risk of death,” without caring who was injured or killed, resulting in Bartell’s death. They appeared in court Thursday morning, after they were arrested Wednesday morning at their homes in Arvada.  

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)

A judge ordered each be held without bond, a court spokesman confirmed.

Karol-Chik said Kwak threw the rock that killed 20-year-old Bartell while she was driving on Indiana Street at about 10:45 p.m. Kwak said Koenig threw it. Koenig refused to be interviewed by police. 

Karol-Chik’s attorney could not immediately be reached. Court records show that the other two men are being represented by the public defender’s office, but did not list the names of their attorneys.

According to the arrest affidavit, Kwak said he remembered hearing a loud noise that sounded like a “rail gun” shooting a block of concrete when the rock smashed Bartell’s window. After seeing the car run off the road, they turned around and he took a photo of the car as a “memento” for Karol-Chik and Koenig. 

On their drive home, the men talked about being “blood brothers” and vowed to never speak about the incident again, the affidavit said. Kwak said he met with Koenig the next day to get their stories straight and deny their involvement. 

Alexa Bartell
Alexa Bartell of Arvada. (Handout)

A friend described Koenig to investigators as someone who frequently partakes in destructive behavior because he likes creating chaos, the affidavit said. He said he was with the three men hours before the rock-throwing spree as they collected landscaping rocks from a nearby Walmart parking lot.

They picked up “as many as they could carry,” placing them in the back seat of their truck, the affidavit said. The friend told police he knew “something bad was going to happen” and asked to be driven home, which he was.

When investigators found Bartell’s car, there was a large hole in the front windshield on the driver’s side and the rear window was completely broken out. Bartell appeared to have a wound to her head and was pronounced dead at the scene, according to the affidavit. 

Near her car, they found a large bloodstained landscaping rock. 

Investigators said Bartell’s car was the last car struck in a series shortly after 10 p.m. in Westminster on April 19. Drivers of two other vehicles suffered minor injuries.

CORRECTION: This story was updated at noon Wednesday, May 3, 2023, to clarify the definition of first-degree murder with extreme indifference.

Olivia Prentzel is a general assignment writer for The Colorado Sun. Email: