Three Colorado 18-year-olds have been charged with first-degree murder after a rock they are accused of throwing went through the windshield of Alexa Bartell, 20, and killed her.

The charges of first-degree murder with extreme indifference against suspects Nicholas Karol-Chik, Joseph Koenig and Zachary Kwak were announced by the Jefferson County Sheriff’s Office Wednesday.

Bartell’s car was the last one struck by a series of landscaping rocks the suspects are accused of tossing in a spree on April 19, starting at around 10 p.m. Bartell’s car was hit at around 10:45 p.m., and the spree ended after midnight.

Law enforcement determined that the rock, not the resulting car crash, was what killed Bartell. Her body was found in a field along with the crashed vehicle by her friend, who was on the phone with Bartell at the time of her death.

At least seven vehicles were hit by rocks; two other drivers suffered minor injuries.

In addition to the three arrested teens, Mr. Koenig’s father, Mark Koenig, was also arrested, accused of getting in the way of sheriff’s deputies as they approached the Koenig family home.

“He was arrested for obstruction,” Jefferson County Sheriff’s Office spokeswoman Jacki Kelley told The Denver Gazette.

• Brad Matthews can be reached at bmatthews@washingtontimes.com.