Three Colorado teens who threw landscaping rock through windscreen of 20-year-old woman while she was driving 'had been hurling rocks at cars for months', investigator claims

Three Colorado teens accused of killing a 20-year-old woman after throwing landscaping rocks through her windscreen 'had been hurling rocks at cars for months', a court has heard. 

Nicholas 'Mitch' Karol-Chik allegedly admitted to throwing objects at moving vehicles between February and April approximately ten times with help from his co-accused, Joseph Koenig and Zachary Kwak, a Jefferson County Sherriff's Office investigator said at a preliminary hearing on Wednesday. 

The trio, all aged 18, are set to face trial after being arrested in April in connection with the homicide of Alexa Bartell. 

The trio allegedly threw rocks at six different cars, causing injuries to multiple drivers and the death of Bartell between 10pm and 12am on April 19 and April 20. 

Koenig and Karol-Chik are also accused of throwing a landscaping 'statue head' at a vehicle carrying a couple and their children earlier that month.

 Zachary Kwak, 18, listens to district court judge Christopher C. Zenisek during an arraignment in Jefferson County district court on May 3, in Golden, Colorado. Kwak allegedly 'had been hurling rocks at cars for months' before the homicide of Alexa Bartell, 20

Joseph Koenig, 18, listens to district court judge Christopher C. Zenisek during an arraignment in Jefferson County district court on May 3, in Golden, Colorado. Koenig was also accused of throwing a landscaping 'statue head' at a vehicle carrying a couple and their children earlier that month

Nicholas 'Mitch' Karol-Chik, 18, listens to district court judge Christopher C. Zenisek during an arraignment in Jefferson County district court on May 3, in Golden, Colorado. He and his two friends allegedly threw rocks at six different cars, causing injuries to multiple drivers and the death of Bartell on April 19

All three suspects have been charged with one count of first-degree murder, one count of extreme indifference, six counts of attempted first-degree murder, three counts of second-degree assault and three counts of attempted second-degree assault.

On April 19 The three teens made plans to meet up and drove to Walmart, where they picked up and loaded landscaping rocks from the parking lot's edge. 

A friend of the trio told police he'd watched them several hours earlier as they loaded a truck with rocks and said the three boys picked up 'as many as they could carry'.

He said he knew 'something bad was going to happen' so asked Koenig, Karol-Chik and Kwak to take him home.

That witness later told police that Koenig 'frequently participates in destructive behavior' because he enjoys causing 'chaos'. 

Koening was driving the truck when the three left the parking lot, according to court documents.

Alexa Bartell, 20, was returning from work around 10:45 p.m. when the large rock sailed through her window shield and fatally struck her

Bartell was driving the Chevy Spark when a rock came crashing through the front windshield

A picture reveals the damage caused to Bartell's car during the attack

Bartell was talking on the phone with a friend while driving in her yellow Chevy Spark at 10:45pm in Arvada, Suburban Denver, when she was hit by the rock. 

After the call went silent, the friend tracked Bartell's location with a phone app, drove to her, and found the woman dead in her car, which had crashed into a field. 

The killing was the fourth of six rock-hurling incidents reported from 10pm onwards on that same evening, causing minor injuries to two other drivers. 

After striking Bartell's windshield, the three suspects circled back and passed the victim's vehicle, which had swerved into a field, at approximately 50 mph to inspect the damage.

Karol-Chik told investigators that Kwak became 'excited' when he hit a vehicle with rocks.  

He also said that Koenig slowed down so Kwak could get a photo of Bartell's car after it crashed into a field. 

He said he felt 'a hint of guilt' passing by her car, although all three got 'excited' every time they hit a car with landscaping rocks, according to court documents. 

Joseph Koenig, Nicholas 'Mitch' Karol-Chik and Zachary Kwak, all 18, are all charged with murder

Kwak said he took the photo because he thought that Karol-Chik or Koenig would want to have a 'memento' of what had happened, according to the arrest affidavits.

Kwak told investigators that Karol-Chik would use 'Marine' terminology, such as 'contact left,' before hitting a vehicle to the left with a rock. 

He reportedly told the others: 'We have to go back and see that.'  

After realizing Bartell was dead, Koenig allegedly called the group 'blood brothers', according to Karol-Chik's interview with authorities. 

Kwak and Koenig were the only two suspects accused of throwing the rock that killed Bartell. 

After investigators interviewed Kwak, he allegedly insisted that he did not throw the rock that killed Bartell. 

When the detective who testified Wednesday told Kwak, 'I hear you,' he responded: 'I don't need you to hear me. I need you to believe me. I did not throw that rock.'