Colorado men charged in fatal rock-throwing spree went back to take photo of crash that killed 20-year-old driver, police say

Three Colorado high school seniors who were arrested for an alleged rock-throwing spree that killed 20-year-old Alexa Bartell outside Denver turned around to take a photo of the fatal crash as a “memento,” according to an affidavit unsealed Thursday.

The suspects — Joseph Koenig, Nicholas "Mitch" Karol-Chik and Zachary Kwak, all 18-year-old high school seniors — were taken into custody at their parents' homes in Arvada, Colo., the Jefferson County Sheriff's Office said Wednesday.

All three were charged with first-degree murder with “extreme indifference,” the sheriff's office said.

Here’s everything we know about the case.

What happened?

On the evening of April 19, according to police, the suspects drove around in a pickup truck and threw large landscaping rocks at at least six vehicles, including a minivan and an SUV, hitting their windshields and driver’s side windows. Two of the drivers suffered minor injuries.

Around 10:45 p.m., Bartell was driving along a road in Jefferson County when a large rock went through her front windshield, hitting and killing her, the sheriff’s office said.

[Friend finds Colorado woman dead after large rock was thrown at her car - NBC]

A friend who was on the phone with her at around that time became concerned when the line dropped. The friend tracked her phone to a field, where Bartell was found.

It’s unclear which of the men threw the rock that killed Bartell, the sheriff’s office added, but all three are suspected of throwing rocks during the hourlong spree.

What led police to the suspects?

The sheriff's office said “mobile device forensics” and information from the public helped lead to the arrests.

According to the 10-page affidavit, authorities received a tip from a tire store worker who told police that a co-worker had recounted how he was with friends who loaded landscaping rocks from a Walmart parking lot into a pickup truck on April 19.

The co-worker later told a detective that he asked his friends to take him home because he "did not want anything to do with what they were about to do," according to the affidavit.

[Suspect in fatal Colorado rock-throwing reportedly ‘had stupid ideas’ - KDVR-TV]

The co-worker said that when they dropped him off, his friends were in Karol-Chik's black pickup truck and that Koenig was driving.

He also told detectives that Koenig "frequently" participates in destructive behavior. When asked why, the co-worker responded: "He likes causing chaos."

What else was revealed in the affidavit?

According to the affidavit, Karol-Chik told investigators that when they hit Bartell's vehicle, Kwak said, "We have to go back and see it." They turned around and drove past Bartell's vehicle; Koenig slowed down so that Karol-Chik could take a photo of it.

Karol-Chik said he felt a "hint of guilt" in doing so.

In his interview with police, Kwak verified Karol-Chik's statements that they turned around and took a photo after Bartell's vehicle was struck. When asked why, he replied that he thought the other two "would want it as a memento," the affidavit says.

[Teens accused in rock-throwing death took 'memento' photo - AP]

He said that during the drive, Koenig and Karol-Chik talked about being "blood brothers" and that they “could never speak of this incident."

Kwak said the three met the next day and "tried to get their stories straight."

Koenig declined to be interviewed, according to the affidavit.

What's next?

The suspects made an initial court appearance via video from jail on Thursday morning. All are being held without bail.

They're due back in court on May 3.