The teenage driver of the truck used in a rock-throwing spree in Jefferson County two years ago hit 103 mph before throwing the fatal rock, a passenger who was riding in the back seat testified Thursday during the driver’s murder trial.
Zachary Kwak testified that Nicholas “Mitch” Karol-Chik urged driver Joseph Koenig to speed up as a car driven by Alexa Bartell, 20, neared the teenager’s truck on April 29, 2023. All three of the men were 18 at the time. Kwak testified that he saw the speedometer hit 103 mph just before Koenig threw a rock into Bartell’s windshield, killing her.
Kwak, now 20, offered the testimony during Koenig’s jury trial in Jefferson County District Court on charges of first-degree murder, attempted murder and related counts related to his role in the 2023 rock-throwing spree.
Prosecutors say Koenig, 20, threw the rock through Bartell’s windshield as the two vehicles passed each other around 10:45 p.m. on Indiana Street near the Rocky Flats National Wildlife Refuge. Koenig’s defense attorneys allege it was Kwak who threw the fatal rock, but acknowledged that, legally, all three men can be held responsible for the death.
Kwak and Karol-Chik, 20, have both pleaded guilty for their roles in the spree and, as part of those plea deals, are required to testify against Koenig.
Kwak testified Thursday that he threw no rocks that night, and admitted only to collecting the rocks from various parking lots and later handing them to Karol-Chik and Koenig, who were in the front of the truck, so they could throw the rocks.
Kwak testified that Karol-Chik and Koenig started out throwing rocks at parked vehicles. Koenig would use a shot-put-like motion to throw the rocks with his left hand as he drove, bringing the rock to his chest and thrusting it out, Kwak testified. Karol-Chik hooked the rocks out of the passenger window, over the truck, and into other vehicles, he testified.
He said the two teenagers would whoop with excitement after the rocks hit cars, and said that while they never saw the damage to cars because it was dark out, they could hear the sound of impacts and glass breaking. Eventually, the teenagers started throwing rocks at moving cars.
After the group spotted Bartell’s car approaching, Karol-Chik urged Koenig to speed up and then handed him a rock, Kwak testified. Someone said, “Last one,” Kwak testified.
“I heard a loud noise, not glass, like a boom, like something striking something,” he testified, adding that the noise was much louder than previous impacts. “The others sounded like a mild smacking noise or shattering glass. This sounded like what they describe artillery shells to sound like in the world wars.”
He saw Bartell’s vehicle drift off the road and Koenig turned the truck around so they could get a better look, he testified. Kwak took a photo on his cellphone; he testified he did so to try to get a more clear view of the damage to the car.
The trio then turned around again and passed by Bartell’s car a second time before going home. Kwak testified that Koenig saw glass with blood on it in the road. He said he knew something was wrong.
“I didn’t think it, but I felt it,” he testified, handcuffed and wearing an orange jail uniform. “I could feel something was wrong.”
As they drove away, the conversation in the truck turned to secrecy, Kwak testified.
“It was a whole lot of, ‘We shouldn’t talk about this,’ ” Kwak said. “Koenig said something about, ‘This makes us blood brothers’ and ‘We can never talk about this.’ ”
Defense attorney Thomas Ward sought to cast doubt on Kwak’s testimony and particularly focused his cross-examination on Kwak’s claims that he barely participated that night, that he threw no rocks that night and that he didn’t join in the celebrations after impacts because he was instead playing a game on his phone in the back seat.
Ward suggested Kwak’s testimony was just an attempt to blame Koenig for the killing so that Kwak could avoid a life prison sentence. (He was originally charged with first-degree murder.)
Ward questioned Kwak about whether Kwak collected the rock used in the fatal attack, and suggested that Karol-Chik tried to stop Kwak from picking up that particular rock because it was “too big.” Ward said Kwak responded to that comment by saying that if Karol-Chik didn’t want to throw it, Kwak would. Kwak denied that the conversation had happened.
Ward also focused on Kwak’s initial lies to police during the investigation.
Kwak on several occasions said he could not remember making particular statements to investigators or describing particular details; prosecutors played clips of his prior interviews with law enforcement at several points during his testimony.
Kwak pleaded guilty to assault and attempted assault and faces between 20 and 32 years in prison. Karol-Chik pleaded guilty to second-degree murder and attempted first-degree murder in 2024 and faces up to 72 years in prison.
Both are scheduled to be sentenced after Koenig’s jury trial.
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