Zachary Kwak on Friday pleaded guilty to one count of first-degree assault, one count of second-degree assault and an added count of criminal attempt to commit assault in connection with the 2023 rock-throwing death of Alexa Bartell.

Her family chose not to speak in court.

A second suspect Nicholas “Mitch” Karol-Chik has also been offered a plea deal by prosecutors. During a court proceeding on Thursday, May 9, which was the plea cut-off, Chief Deputy District Attorney Katharine Decker said that prosecutors had extended an offer to Karol-Chik with a “floor of 35 years in prison.”

This means that the minimum sentence would be 35 years. 

Karol-Chik has not accepted the offer, but he has a disposition hearing scheduled for May 15. His attorney, Holly Gummerson, said that she could not comment on the development. 

Kwak, Karol-Chik and Joseph Koenig were arrested a week after the rock-throwing incident and eventually were charged with first-degree murder in the death of the 20-year-old Arvada woman. 

Bartell died on April 19, 2023 at around 10:45 pm when a large landscaping rock thrown from a Chevy Silverado truck going 50-60 miles per hour slammed into her windshield. 

Kwak, 19, was in the back of the vehicle, Koenig was driving and Karol-Chik was in the front passenger seat, according to court testimony.

On Friday, during his disposition hearing, Kwak was dressed in a yellow jail outfit and spoke clearly in affirmation when asked if he understood his decision. 

First Judicial District Judge Christopher Zenisek said that Kwak’s bond and remaining jury trial dates have been vacated.

His attorney, Emily Boehme, asked for a prison sentence of 20 to 32 years. Sentencing won’t take place until the resolution of the other two criminal cases.

The arrest documents showed that at least six other cars were hit that night in a 45-minute span, injuring some victims and leaving others befuddled about what happened, even wondering if a wind storm had come through the area.

Kwak told investigators that he had only just met the other two defendants weeks before the incident. Karol-Chik and Koenig had been lobbing large rocks at oncoming vehicles since February, prosecutors said. During his interrogation, Karol-Chik said that he and Koenig had been on rock-throwing missions 10 times before the night Bartell was killed.

That information will not get into any of the trials, Zenisek ruled last week.

There is only corroborating evidence that Karol-Chik and Koenig threw rocks at three other vehicles in Jefferson County on two separate nights. 

Three other drivers were injured in the crime spree, which lasted 45 minutes as the three suspects allegedly drove around northwest Jefferson County lobbing landscaping rocks from either a sunroof or from side windows, according to the arrest affidavit. Seven cars were hit between 10 and 10:45 p.m. that night.

Kwak’s first-degree assault count is for Bartell’s death. The second-degree assault charge accounts for the three victims who were injured, and the third charge — criminal attempt to commit assault — represents the three victims who were not injured the night of the rock-throwing spree.

In a chilling statement to Jefferson County Sheriff’s deputies, Kwak said that, after they hit Bartell’s car, the three made a U-turn and drove by and he took a photo of the car for a memento. The next day, Kwak and Koenig vowed to stay mum about their night of deadly mischief and came up with a corroborating story about what happened, according to the arrest affidavit. 

Despite those plans, Kwak and Karol-Chik gave investigators conflicting stories as to who threw the rock that killed Bartell. Koenig never gave an interview. 

Denver criminal defense attorney David Beller said to expect Kwak to be a critical key for the prosecution’s case in the upcoming trials of the two remaining defendants, Koenig and Karol-Chik. Beller said that, though it wasn’t said publicly in court, “the plea considers future cooperation with the prosecution in the trials against the co-defendants.”

Beller, with Recht Kornfeld, said that a cooperating defendant like Kwak can be “a powerful tool for the state.” 

Beller added that, if Kwak takes the stand against Karol-Chik and Koenig, the public should expect for the defense to argue his bias. His performance during testimony would be “a deciding factor in what sentence he will ultimately receive,” Beller said.  

Kwak is expected to be sentenced Sept. 3 after the trials of Koenig and Karol-Chik are resolved.

Karol-Chik will be the first to stand trial starting with jury selection scheduled to start June 7. Koenig’s trial is scheduled to begin July 19, a Friday, and end around August 1.