One of three Colorado teens pleads guilty in rock-throwing death of young woman

Courtesy of the Jefferson County Sheriff's Office
The shattered windshield of Alexa Bartell’s car. Three suspects allegedly threw a rock at her while she was driving in Jefferson County on the night of April 19. The impact of the rock killed her.

A teen accused of killing a 20-year-old woman by throwing a rock that crashed through her windshield in 2023 pleaded guilty in Jefferson County Court Friday. 

Zachary Kwak, 19, was one of three suspects in the incident. He pleaded guilty to first-degree assault, second-degree assault and attempted second-degree assault. Thirteen counts, including murder and attempted murder, were dismissed and Kwak's bond was revoked.

Courtesy of family via Jefferson County Sheriff's Office.
Arvada resident Alexa Bartell, 20, was killed after she was struck by a rock that was thrown through her car windshield on Wednesday, April 19, 2023.

Kwak could be sentenced to up to 32 years in prison. As part of the plea agreement, he is not eligible to be sentenced to a youth offender program.

Two other 19-year-olds, Joseph Koenig and Nicholas Karol-Chik, are also charged with first-degree murder for the death of Alexa Bartell and multiple counts of attempted murder. Their trials are scheduled for later this summer. They both pleaded not guilty to more than a dozen charges last month.

Bartell, the young woman who was killed, was talking on the phone with a friend while driving when a large rock destroyed her windshield. After the call went silent, the friend tracked Bartell's location with a phone app and found the woman dead in her car. The rock killed Bartell, not the crash, according to a spokeswoman with the Jefferson County Sheriff’s Office.

The three suspects reportedly drove around and threw large rocks at other passing cars in Jefferson and Boulder counties on that same April 2023 night. Other people were injured in those incidents, and at least one reported seeing someone hurl the stone from the back of a truck. The suspects are accused of participating in similar behavior days prior.

All suspects were 18 and high school seniors at the time of their arrests.

Kwak’s sentencing is scheduled for September.