Nicholas Karol-Chik: Plea Deal, Sentence, and Reduction Denial

Nicholas “Mitch” Karol-Chik was sentenced on May 1, 2025 to 45 years in the Colorado Department of Corrections, followed by eight years of mandatory parole, for his role in the 2023 rock-throwing spree that killed 20-year-old Alexa Bartell in Jefferson County. The sentencing of Nicholas Karol-Chik followed a plea deal in which he admitted to second-degree murder and attempted first-degree murder and agreed to testify against co-defendant Joseph Koenig, who prosecutors said threw the fatal rock.¹

The Plea Deal

Karol-Chik was originally charged, along with Koenig and Zachary Kwak, with first-degree murder, attempted first-degree murder, and assault-related counts.² In May 2024 he reached an agreement with the First Judicial District Attorney’s Office. The first-degree murder charge with extreme indifference was dismissed. He pleaded guilty to second-degree murder in Bartell’s death and to attempted first-degree murder for throwing rocks at nine other people during the spree.¹ The charges carried a crime-of-violence enhancer.³

The deal required Karol-Chik to cooperate with prosecutors and testify against Koenig at trial. It left him facing a stipulated sentencing range of 35 to 72 years in prison.⁴

The May 1, 2025 Sentencing Hearing

First Judicial District Court Judge Christopher Zenisek imposed the 45-year sentence for second-degree murder along with a concurrent 24-year sentence for attempted first-degree murder. The result landed in the middle of the stipulated range. Zenisek pointed to what he called “a pattern of conduct, not only on this night but other nights, as well.”¹

Deputy District Attorney Brynn Chase, who led the prosecution, acknowledged Karol-Chik’s cooperation but pushed back against further leniency. “With the level of seriousness of the offense, there’s just no way to atone for what the three of them did but for a substantial sentence to the Department of Corrections,” she told the court. “There’s a sadness attached to that, but it is the measure of justice that is required here.”⁵ Chase stressed that although Koenig threw the fatal rock, the killing happened because Karol-Chik “passed the fatal rock to Koenig moments before.”¹

Karol-Chik apologized to Bartell’s family and told the court he had been “heavily influenced by the people around him because of unhappiness” at the time of the crimes, and that he is not the same person today.³ Bartell’s family had urged Judge Zenisek to impose the maximum sentence.

His Role in the Attacks and the Fatal Rock

Karol-Chik did not throw the rock that killed Bartell, but prosecutors and the judge treated his role as central to the crime. He admitted to investigators that he and Koenig had thrown rocks and at least one statue at passing cars on at least ten separate days before April 19, 2023.⁶ On the night of the killing, all three drove through Jefferson and Boulder Counties throwing large landscaping rocks stolen from a Walmart parking lot. Karol-Chik testified that the trio threw about ten rocks each that night, targeting the driver’s side of vehicles.⁷ The rock that killed Bartell weighed 9.3 pounds.¹

At Koenig’s trial, Karol-Chik testified that he placed the fatal rock on the truck’s center console for Koenig to grab, and that Koenig hurled it out the driver’s side window with a shotput-like motion as the truck approached Bartell’s car. After the crash, the three circled back to the scene rather than call 911. Karol-Chik testified that Koenig appeared “excited” and made a celebratory sound as they drove past.⁸

His account of who threw the fatal rock changed over time, and that shift shaped how his cooperation was viewed. In early interviews he blamed Kwak, later admitting he lied to protect Koenig, his closest friend. He testified that Koenig had told him, “we won’t have to worry about it because we’ll just say that Zach did it.” Even after his attorneys signaled a change in his story in December 2023, he still named Kwak at a January 2024 proffer, saying he was “100% sure” Kwak threw it. Only in April 2024 did he tell investigators, “I think it was Joe.”⁹

Koenig was convicted on all 19 counts on April 25, 2025.¹⁰

Denied Request to Reduce His Sentence

In September 2025, months into his prison term, Karol-Chik filed a motion for post-sentencing review asking Judge Zenisek to cut ten years off his 45-year sentence. He cited good behavior and his application to a ten-year education program through which he hoped to earn a bachelor’s degree in Christian studies and work as a prison chaplain.¹¹

Judge Zenisek declined to hold a hearing and denied the motion in a brief order on October 8, 2025. “The court, in its discretion, determines that the sentence is appropriate as originally imposed due to the severity of the offense and community safety concerns,” he wrote.¹¹

How Karol-Chik’s Sentence Compares to His Co-Defendants

All three defendants were 18 at the time of the attacks and 20 at their sentencings. Their outcomes diverged sharply based on their roles and their willingness to cooperate.

Zachary Kwak pleaded guilty in May 2024 to first-degree assault, second-degree assault, and attempted second-degree assault, avoiding murder charges. He was sentenced on May 2, 2025 to 32 years in prison, the maximum under his plea. Judge Zenisek said Kwak had “lesser involvement” than the other two, while noting Kwak admitted to collecting the rocks and did not call for help after Bartell was killed.¹²
Joseph Koenig rejected a plea deal, went to trial, and was convicted on all 19 counts, including first-degree murder with extreme indifference. On June 3, 2025, Judge Zenisek sentenced him to life in prison without the possibility of parole for the murder, plus 60 consecutive years on the remaining counts. The judge said Koenig’s sentence “should be comparable to but greater than” those of his co-defendants, calling the act of throwing the fatal rock “more vicious, deliberate, intentional.” Koenig’s attorneys announced plans to appeal.¹⁰¹³

Karol-Chik’s 45-year sentence sits between the two: longer than Kwak’s, because he was charged with and admitted to Bartell’s murder and to attempted first-degree murder of nine other people, and shorter than Koenig’s life sentence, reflecting both the difference in their acts that night and his cooperation with the prosecution.

1
Colorado Sun. Rock Throwing Death
2
ABC News. Teens Accused of Deadly Rock-Throwing Spree Formally Charged
3
Denver Gazette. Co-Defendant Sentenced to 45 Years in Prison for Rock-Throwing Death
4
KRCG TV. Colorado Man Found Guilty of First-Degree Murder After Deadly Rock-Throwing Incident
5
First Judicial District Attorney’s Office. Nicholas Karol-Chik Sentenced to 45 Years in Prison
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KSLA News. 3 Colorado 18-Year-Olds Charged With Murder in Rock-Throwing Death
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CNN. Colorado Rock Through Windshield Death
8
CPR News. Rock-Throwing Trial Guilty Koenig
9
Denver7. Second Co-Defendant Testifies Against Close Friend on Trial for Murder of Alexa Bartell
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First Judicial District Attorney’s Office. Joseph Koenig Sentenced
11
Denver Post. Colorado Rock-Throwing Spree Sentence Reduction
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Colorado Sun. Zachary Kwak Sentence Rock-Throwing Spree Alexa Bartell
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Denver7. Joseph Koenig’s Attorneys Plan to File Appeal After Sentencing