Teen pleads guilty in Colorado rock-throwing spree that killed 20-year-old driver

One of three Colorado teenagers charged in connection with a rock-throwing spree that killed a 20-year-old driver last year has pleaded guilty as part of a plea deal, officials said Friday.

Seven vehicles were hit by large landscaping rocks on the night of April 19, 2023. Three people were injured and one -- Alexa Bartell, the final victim -- was killed, prosecutors said.

Three then-18-year-old seniors were charged with 13 counts -- including first-degree murder with extreme indifference -- in connection with the incident.

One of the teens -- Zachary Kwak, now 19 -- pleaded guilty Friday to three new charges in connection with the rock-throwing attack, according to the Colorado First Judicial District Attorney’s Office, which is prosecuting the case.

Kwak pleaded guilty to first- and second-degree assault and criminal attempt to commit assault in the second degree. Kwak's original charges were dismissed as a result of his plea, the district attorney's office said.

"As part of today’s plea, Kwak agreed that with regard to the death of Bartell, the defendant acted knowingly, under circumstances manifesting extreme indifference to the value of human life, by engaging in conduct which created a grave risk of death," the Colorado First Judicial District Attorney’s Office said in a statement.

Kwak's attorneys had no comment on the plea deal.

Kwak faces 20 to 32 years in prison as a "result of his plea and cooperation," the district attorney's office said. He is scheduled to be sentenced on Sept. 3, following the resolution of the cases involving the other two teens charged in the rock-throwing spree, Joseph Koenig and Nicholas "Mitch" Karol-Chik.

First-degree murder with extreme indifference carries a mandatory sentence of life in prison if convicted.

The three teens were all being tried separately. Karol-Chik's trial is scheduled to start on June 7, while Koenig's trial is set to start on July 19.

Both pleaded not guilty to their charges.

Karol-Chik allegedly told police while in custody that all three teens threw rocks at cars and they were "excited" when they hit them, according to court documents.

When Kwak was questioned, he allegedly said he took a photo of Bartell's car because he "thought Joseph or Mitch would want it as a memento," according to court documents.

After Bartell's death, Kwak allegedly said Koenig and Karol-Chik talked about being "blood brothers," and said they agreed to never speak of the incident again, according to court documents.