A jury last week convicted a Colorado man of first degree murder for his part in a night of teenaged rock-throwing that killed a woman as the landscaping stone he hurled crashed through her windshield and struck her.

Two co-defendants pleaded guilty for their parts in the April 19, 2023, incident that killed Alexa Bartell, but Joseph Koenig, now 20, held out for a jury trial, The Associated Press reported.

Bartell, 20, was driving northbound on Indiana Street in Golden near the Rocky Flats National Wildlife Refuge, on the phone with her girlfriend,and was struck in the head by a rock, killing her, as CrimeOnline reported. The call went silent, and the girlfriend tracked the phone and found Bartell dead in her vehicle, which had veered into a field. The medical examiner said she was killed by the rock not the crash.

Investigators later learned the boys intentionally drove toward Bartell’s vehicle and slowed down to take a photograph of the crashed car as a “memento” of what happened. They did not stop to help.

That same day, two other victims were injured in earlier assaults involving rocks, while seven vehicles in total sustained damage from what authorities have characterized as “large landscaping rocks.” According to reports, the suspects may have been traveling in a moving vehicle at the time the rocks were thrown.

The boys were ultimately arrested after police identified them based on cellphone data and information from a friend who had been socializing with them before they began hurling rocks at vehicles.

Koenig was arrested, along with Zachary Kwak and Nicholas Karol-Chik, all three 18 at the time of the murder. Kwak was the first to plead guilty nearly a year ago, copping to first degree assault — acting a way that created a grave risk of death — as well as second degree assulat and attempted assault for earlier instances of rock throwing that night.

Karol-Chik pleaded guilty a week later, admitting to second degree murder, committing a crime of violence, and attempted first degree murder for earlier rock throwing instances.

According to the AP, Bartell’s family and friends hugged and cried after the verdict was read.

“It’s hard to be happy or feel satisfied that justice was served today, because I feel one amazing life was lost and three others are also lost and impacted,” her mother, Kelly Bartell, said.

Koenig’s attorneys attempted to blame his co-defendants for the rock — a 9-pound landscaping stone taken from a Walmart parking log — that killed Bartell. But both his co-defendants pointed the finger at him, although Karol-Chik initially blamed Kwak before his guilty plea.

Prosecutors said the damage to Bartell’s car was consistent with the left-handed Koenig throwing the rock out his driver’s window, which was Karol-Chik’s testimony.

The jury rejected lesser charges for him, particularly after hearing that the three teens circle past the crashed car a few times to look at it but never stopped to check on the driver or call for help. Kwak even took a photo for a “memento.”

Karol-Chik testified that Koenig made a “whoop” sound as they drove by Bartell’s crashed car. “It sounded like him celebrating,” he said.

Kwak and Karol-Chik’s sentencing was delayed until after Koenig’s trial. Karol-Chik could be sentenced to 35 to 72 years when he is sentenced on Thursday, and Kwak faces 20 to 32 years at his sentencing on Friday.

Koenig was also found guilty of attempted murder and other crimes for the earlier rock-throwing instances.

Koenig’s sentencing is set for June 3. He faces a mandator life sentence.