Three teenagers charged with killing Colorado woman, 20, by throwing a ROCK through her windscreen plead not guilty - as one is charged with attacking OTHER motorists

Three Colorado teenagers charged with killing a 20-year-old woman by throwing a huge rock through her windshield have pleaded not-guilty to her murder. 

Alexa Bartell, 20, was killed when Joseph Koenig, Nicholas 'Mitch' Karol-Chik and Zachary Kwak, all 18, allegedly hurled a landscaping rock at her car in Arvada, Colorado, on April 19 2023.

Appearing in Jefferson County District Court on Monday, the teenagers pleaded not guilty to first-degree murder with extreme indifference - Koenig is also facing four new charges of attempted murder and assault for separate rock-throwing incidents.

Prosecutors say the men had thrown giant landscaping rocks and hit six other cars that night, but all the other drivers were uninjured. 

Bartell was on the phone with a friend when a rock smashed into her car and she went quiet. Her friend tracked her phone and drove to the location to find her dead in her car, which had plowed off the road into a field. 

Alexa Bartell, 20, was killed when when a landscaping rock was thrown through her windshield in Arvada, Colorado, on April 19

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

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

The men will be tried separately, with Karol-Chick appearing in court first in June. 

Four new charges of two counts of attempted first-degree murder and two counts of attempted second-degree assault have also been brought against Koenig after two more victims came forward for rock-throwing incidents in February 2023.

In court on Monday, prosecutors said Karol-Chick had admitted he and Koenig had thrown rocks on ten nights last year but had only caused property damage. 

At a previous court appearance, Prosecutor Padraic Emerine said: 'This was an extremely reckless and irresponsible situation that the defendant was involved in that, unfortunately, cost the life of a very innocent and very young woman in this case.'

A sheriff's office arrest affidavit said that after the fatal attack, Kwak told the others: 'We have to go back and see that.' He then allegedly took a photo of her car as a 'memento'. 

A friend of the trio told police he'd watched them several hours earlier as they loaded a truck with landscaping rocks taken from a Walmart parking lot. The friend claimed 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.

The three alleged killers then patrolled roads in the area and searched for passing cars to target. 

Kwak said they would use 'marine terms' when launching the rocks, adding: 'Mitch would say things like, ‘contact left,’ before Joseph would throw the rock at a car on the left side of theirs.' 

He said the rock which killed Bartell made a 'very loud noise... like a rail gun' when it struck her windshield. A bloodstained rock was discovered next to the young woman's yellow Chevy Spark.

Koenig was described by a friend as someone who likes creating 'chaos' and would often act in a destructive manner. 

'Joseph and Mitch were talking about them now being ‘blood brothers’ and they could never speak of the incident,' Kwak added.

The three reportedly met up the following day to 'get their stories straight'. 

Karol-Chik and Kwak were interviewed by detectives and each gave different accounts about who threw the rock. Koenig refused to speak to police.  

The affidavit said one of the suspects said he felt 'a hint of guilt' and revealed the men were traced using data from cell towers in the area.

After the attack which killed Bartell, Kwak allegedly told the others: 'We have to go back and see that.' He then took a photo of the car, which had careered of the road, as a 'memento'

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

Police offered a $17,000 reward to capture Bartell's killers

It added that they had thrown rocks at vehicles on about ten occasions since February. Six other cars were damaged and two more drivers were injured on the night Bartell was killed.

Lyft and Uber driver Nathan Tipton was uninjured after being targeted.

Speaking to reporters at a news conference, he said he was headed southbound on Highway 93, close to the Jefferson County and Boulder County lines, at around 10.15pm.

'I saw two vehicles going northbound, but all I could see was the headlights, it was a dark road,' he said. 'And then a large shatter - it sounded like a shotgun blast. It scared the heck out of me.'

He said he pulled over right away and saw that both driver-side windows of his mini van had been shattered.

'It's horrible. Nobody should lose their child for a random act of whatever this is,' he added.

A $17,000 reward had previously been offered for information.