NewsLocal News


Rock-throwing suspects went back to scene of JeffCo fatal crash to keep photo as a memento, affidavit says

Suspects swore to secrecy after causing crash, according to the document
Posted: 11:32 AM, Apr 27, 2023
Updated: 2023-04-28 00:31:53-04
Other victim 1 car documentation.png
Other victim 2 car documentation.png

JEFFERSON COUNTY, Colo. — Three teens accused of throwing a rock at a car in Jefferson County, killing the driver, drove by the crashed vehicle to take a photo as a memento, according to the newly released affidavits.

On Thursday morning, the affidavits for the three 18-year-olds arrested in connection with multiple rock-throwing incidents, including one that killed a 20-year-old driver, were released.

The Jefferson County Sheriff’s Office announced on Wednesday morning that Joseph Koenig, Nicholas “Mitch” Karol-Chik and Zachary Kwak had all been arrested.

alexa bartell.png

Local News

18-year-old suspects arrested in rock-throwing spree that killed Alexa Bartell

Jeff Anastasio
6:53 AM, Apr 26, 2023

Jefferson County Sheriff’s Office deputies investigated the fatal case late on April 19. They determined that Alexa Bartell, 20, had been on the phone with her friend around 10:45 p.m. when Bartell “abruptly stopped talking,” the affidavit reads.

When the friend was able to leave work, around 11:05 p.m., she used the Find My iPhone app to find Bartell. Through the app, she saw her friend’s phone was stationary in a field on the east side of Indiana Street, just south of State Highway 128, according to the affidavit.

The friend drove to that location and found Bartell with a serious head injury in the driver’s seat of her Chevrolet Spark. She was not moving, according to the affidavit. The friend called Bartell’s mother and then 911.

Woman killed by large rock thrown at her vehicle in JeffCo., deputies say

Officers with the Broomfield Police Department were the first ones to arrive at the scene. The first officer at the crash recalled blood on the car door and on the woman’s lap, according to the affidavit. Bartell was unresponsive and the officer was unable to find a pulse.

The North Metro Fire Department also responded to the scene. Medical personnel pronounced Bartell dead. When Colorado State Patrol arrived, they determined the car’s damage was not consistent with a crash and appeared to “be the result of an object penetrating the windshield and striking Alexa in the head,” the affidavit reads.

The windshield had a hole in front of the driver’s seat.

Alexa Bartel car hit by rock

When looking at the area around the car, crime scene analysts with the sheriff’s office found tire tracks in the grass where the car ran off the road. Further south, they found a landscaping rock on the side of the road. The rock had a red stain on it, which later tested presumptively positive for blood, according to the affidavit.

The sheriff’s office later learned about two separate incidents in which vehicles were struck by rocks that were thrown by a person in an on-coming vehicle. Both of these cases happened around 10:40 p.m. on McCaslin Boulevard north of State Highway 128 the same day Bartell was killed.

What other victims reported

The arrest affidavit included more details on those two rock-throwing incidents.

A Jefferson County Sheriff’s Office investigator interviewed Driver 1, who was behind the wheel of a Subaru and attempting to turn onto Indiana street around 10:40 p.m. April 19.

Driver 1 said when he saw a light-colored SUV or pickup truck approach his vehicle, he noticed a large rock was launched from the other vehicle. The rock crashed through his windshield and struck him in the shoulder, according to the affidavit.

Driver 1 believed the rock was thrown from either a sunroof or the bed of a pickup truck based on the trajectory, the affidavit read.

The landscaping rock, as described by the Boulder County Sheriff’s Office, was located on the front seat of Driver 1’s vehicle and later analyzed by the Jefferson County Regional Crime Laboratory.

According to new details from the affidavit, there was a “two contributor DNA sample identified on the rock that was suitable for comparison,” meaning analysts found evidence of two people coming in contact with the rock they could use. The affidavit did not reveal the identity recovered from the sample.

Other victim 1 rock documentation.png

In a separate incident, investigators interviewed another person who was driving southbound on McCaslin just behind Driver 1.

In the affidavit, this person, identified as Driver 2, stated he saw Driver 1’s vehicle swerve in front of him and then saw and felt “an object” hit the front of his car.

He pulled over and noticed damage on both his vehicle and Driver 1’s Subaru.

Driver 2 located the rock he believed hit his vehicle in the road, according to the affidavit.

Other victim 2 rock documentation.png

During the investigation into these two cases, as well as the fatal one near Indiana Street, officials uncovered four additional rock-throwing attacks that all allegedly also occurred on the night of April 19:

  • At around 10 p.m., Driver 3 was headed westbound on W. 100th Avenue near Simms Street when he stated he saw someone in an eastbound vehicle throw a rock at his car, shattering the windshield, the affidavit read. Driver 3 had minor injuries.
  • Driver 4 was traveling southbound on Highway 93 near State Highway 72 when her windshield was also struck by a rock, according to investigators. Driver 4 said she didn’t see any other vehicles and had minor injuries on her face.
  • At 10:15 p.m., Driver 5 was headed south on Highway 93 near State Highway 128 when the rear and driver’s side windows of his vehicle were broken by what he described as an unknown object. According to the affidavit, Driver 5 first thought his vehicle might have been hit by flying debris due to the winds. He did not report seeing any other vehicles in the opposite lane or on the side of the road.
  • Driver 6 was traveling south on Highway 93 near State Highway 128 behind Driver 5’s vehicle. In the affidavit, Driver 6 said at about 10:30 p.m., a northbound truck passed him, “debris hit and cracked his windshield and damaged his car.”

Cell tower data helps identify suspects

On April 20, an investigator with the sheriff’s office requested a data dump from a cell tower and was provided information from all phone carriers, according to the affidavit. This included several files from Verizon RTT data, which is a collection of all of the phones that connect with a tower to make calls or send texts. This includes location data.

Using repeated RTT data, investigators can create a trail to show how a phone moves.

The investigator sent the records to a company for analysis and asked for information on any phones that hit four specific locations.

On April 24, the company finished processing the data and found 11 phone numbers that had connected to the four towers. The investigator noticed that one cell phone in particular was moving in the area at the same time as the rock-throwing incidents. That phone also passed by the area where Bartell was killed, according to the affidavit.

The investigator determined that the phone number may belong to Koenig. Using a law enforcement database, he found that it was listed to a woman who appeared to be Koenig’s mother.

Using this information and additional RTT data, the investigator mapped Koenig’s cell phone movements between 9:50 p.m. and 11:07 p.m., according to the affidavit.

In addition to cell phone data, the sheriff’s office also obtained security camera footage. Both showed the vehicles driven by Driver 1 and Driver 2 heading south, hitting their brakes and then turning their hazard lights on. Only one other vehicle was on the road at the time, which was driving north and appeared to be speeding. According to the footage, it appeared that the vehicle was a dark-colored pickup truck, according to the affidavit.

An investigator sent images of that vehicle’s tail lights to Len Lyall Chevrolet, which confirmed the car as a 2014-2016 Chevrolet Silverado.

Three teens arrested, 2 interviewed by investigators

On April 25 around noon, an investigator received a phone call from the Westminster Police Department about a man who said he had information about the incident, according to the affidavit. The person said his coworker, identified hereafter as Witness 1, started discussing the rock-throwing incidents on April 25 while they were both at work.

The tipster said Witness 1 told him on April 19, he had seen a person named “Joe” and “Mitch” plus a third person loading rocks into their vehicle from a Walmart parking lot. Witness 1 told the trio to “take him home because he did not want anything to do with what they were up to,” according to the affidavit.

That same day, investigators met with Witness 1. He said he was a former coworker of Koenig. He said he got a call on Snapchat on April 19 around 6:30 p.m. from the suspect asking if he wanted to hang out and Witness 1 agreed.

Koenig arrived at his house with another friend “Mitch” — later identified as Karol-Chik, who goes by Mitch — and a person Witness 1 did not know very well named “Zach,” later identified as Kwak. Koenig was driving a black Chevrolet Silverado 1500 pickup truck. Witness 1 told investigators he thought it might be around a 2019-2020 model but wasn’t sure.

Witness 1 told investigators the story he had relayed to his friend at work, who had then contacted police. Witness 1 said they all drove around for a couple hours until they ended up in the parking lot of the Walmart near W. 72nd Avenue and Sheridan Boulevard. They went inside, walking around the store when Witness 1 decided to go to the bathroom. When he came back, he said Koenig, Karol-Chik and Kwak were picking up landscaping rocks from the edge of the parking lot and putting them in the back seat of the truck they were driving.

Witness 1 asked them how many rocks they were going to take. Koenig replied “as much as they could carry,” according to the affidavit.

Witness 1 said he knew something bad was going to happen, so he insisted they take him home, which they did, according to the affidavit. He said as the pickup pulled away, Koenig was driving, Karol-Chik was in the front passenger’s seat and Kwak was behind Karol-Chik.

Witness 1 told investigators that Koenig frequently participates in destructive behavior. When pushed to elaborate, he said Koenig told Witness 1 he likes causing “chaos,” the affidavit reads.

When asked, Witness 1 told investigators he believed the trio had their cell phones on them because Koenig had called him on Snapchat. He recalled another person playing music through the truck speakers with their phone.

After this interview, investigators searched social media to identify the person Witness 1 had known only as Mitch. Witness 1 said he didn’t know his full name. They found Koenig had a friend named Nicholas Karol-Chik with the username Mitch. During a search of a database, officials found a 2016 black Chevrolet Silverado registered to a person who appeared to be Karol-Chik’s mother.

When investigators searched through the data from cell phone towers, they also noted that a phone number for Karol-Chik showed similar locations to Koenig’s cell phone, according to the affidavit.

Deputies then drove to Karol-Chik’s home, where they saw a black Chevrolet truck, with no front plate, parked in the driveway. It was a 2016 model, according to the affidavit.

A search warrant was obtained and the Chevrolet was seized.

Later that same day — April 25 — deputies took Karol-Chik into custody. They also learned his preferred name was Mitch. Around 12:40 a.m. the following day, investigators interviewed him after he agreed to speak.

Karol-Chik described the route the teens drove on the evening of April 19, which matched cell phone tower data and surveillance camera footage timelines. He said prior to any incidents, he drove his truck to pick up Kwak and Koenig.

Karol-Chik originally said that only Kwak collected and threw the rocks. He recalled that Koenig seemed excited when he hit a car and after striking Bartell’s vehicle, said, “We have to go back and see that,” according to the affidavit.

But he said later in the interview that both he and Kwak collected rocks and all three of them threw them at moving cars. He also admitted that he and Koenig had thrown other objects, including a statue and rocks, at cars since February on at least 10 other occasions. On April 19, Kwak expressed interest in joining them for more rock-throwing.

That evening, Karol-Chik said they all got excited when they’d hit a car. He said Kwak was the one who threw the rock that hit Bartell’s vehicle, the affidavit reads. He told investigators that Koenig slowed the car afterward, turned around to go southbound and let Kwak take a photo of the car. Karol-Chik said he “felt a hint of guilt,” according to the affidavit.

Around the time of this interview, both Koenig and Kwak were also taken into custody.

Koenig was arrested around 11 p.m. on April 25 and Kwak was arrested around 2 a.m. on April 26. Koenig declined to be interviewed. Kwak agreed to talk.

Three 18-year-old suspects arrested in connection to rock-throwing spree that killed Alexa Bartell

Initially in the interview, Kwak said he could not remember the incident. But after investigators told him they had information about him being in the pickup that evening, Kwak did say they went to a Walmart in Denver before driving around town, according to the affidavit. He did not provide information about where else the group drove the evening of April 19.

He said he remembered stopping and collecting rocks, and then throwing them at cars. He said Koenig was driving at the time and Karol-Chik was in the front passenger seat. He said Karol-Chik would help guide Koenig on when to throw the rocks, according to the affidavit.

When they threw a rock at Bartell’s vehicle, Kwak said “the impact made a very loud noise” and when he looked back, he saw the car had gone off the road, the document reads. When they turned around to pass the car, Kwak said he used his phone to take a picture, adding “he thought (Koenig) or (Karol-Chik) would want it as a memento,” the affidavit reads.

The group then headed back home, and Koenig and Karol-Chik swore they would never speak of the incident. Kwak said the following day, Koenig met with him to “get their stories straight… specifically denying involvement,” the document reads.

All three suspects were in court Thursday morning for their advisement hearings. They are all due in court on May 3 for a filing of charges.

Jeffco rock-throwing suspects go before a judge Thursday

Alexa Bartell Memorial Fund

In a statement, Bartell's family said their worlds were "forever changed" the night of April 19. They described Bartell as "intelligent, kindhearted soul, with a bright future ahead of her."

"At 10:45 pm on April 19th, 2023, our worlds were forever changed. Our beautiful Alexa was driving in Arvada, Colorado and was struck by a large rock thrown through the windshield of her car, tragically taking her life. This was not an accident, but instead – an intentional act of violence and malice by 3 strangers.

Alexa was an amazing daughter, granddaughter, sister, niece, cousin, and friend. She was an intelligent, kindhearted soul, with a bright future ahead of her. Alexa would do anything for those she knew and loved. This beautiful young life was taken way too soon.

Alexa’s family has been asked how others can help with future expenditures resulting from this tragedy. In lieu of flowers, a memorial/justice fund has now been set up in Alexa’s name. This fund is open to accepting donations from the public. All proceeds will go directly to assist the family with future legal expenses, create an endowment fund for student athlete opportunities, and creating a permanent memorial in Alexa’s honor.

We thank you for all of the thoughts, prayers, postings, and assistance in getting the word out about finding justice for our irreplaceable Alexa."

In lieu of flowers, the family is asking for donations to a memorial/justice fund. According to the statement, all proceeds will go to the family to assist with future legal expenses, create an endowment fund for student-athlete opportunities and create a permanent memorial in Bartell's honor.

Donations can be made directly to the Alexa Bartell Memorial Fund at FirstBank. The family is also accepting donations via Zelle at as well as via Venmo at @Alexa-Bartell-4. Donors can also use the QR code below to donate. Venmo may ask for the last four digits of the associated phone number, which are 1166.

Alexa Bartell Memorial Fund Venmo QR code

D7 follow up bar 2460x400FINAL.png
The Follow Up
What do you want Denver7 to follow up on? Is there a story, topic or issue you want us to revisit? Let us know with the contact form below.