Affidavit: Colorado suspects threw objects at cars before, photographed victim's vehicle after deadly rock strike

The three suspects accused of throwing rocks at cars last week, killing one woman, appeared in court via Zoom from the Jefferson County Jail Thursday morning.

Alexa Bartell, 20, was killed April 19 when one of those landscaping rocks went through her windshield while she was driving on the 10600 block of Indiana Street close to the Jefferson County and Boulder County lines. Her vehicle left the roadway and ended up in a field. She was on the phone talking to a friend when she was struck and the phone went silent.

Broomfield police and North Metro Fire Rescue crews arrived and found Alexa in her car with a significant wound to her head, not moving and with no pulse. Investigators found a river rock on the side of the road with red staining that tested presumptive positive for blood. 

Joseph Koenig, Nicholas "Mitch" Karol-Chik and Zachary Kwak were arrested Tuesday night into Wednesday morning. The suspects are all high school seniors.

The suspects didn't appear to show any emotion from their Zoom hearing and Kwak had his head down the entire time.

According to the arrest affidavit just released Thursday morning, the three suspects had been throwing objects, including a statue, at vehicles since at least February. Investigators said at least one of the suspects admitted to that type of behavior on 10 separate days. 

In the incident last week, they allegedly went back and took a picture of the car after it was hit and went off the road.

Two other people were also hurt in earlier rock attacks the night of April 19. Seven vehicles in total were hit by what authorities now describe as "large landscaping rocks." It's believed the suspects were in moving vehicle when the rocks were thrown.  

Investigators say they used cellphone sites to find the suspects.

They sought warrants from cellphone companies called "geofencing warrants," or reverse warrants.

RELATED: Survivor of Colorado rock-throwing attacks speaks out: "It's horrible. Nobody should lose a child"

The idea is that any phones at more than one spot regarding the incidents may be the phones of potential suspects.

But there have been questions about security and unreasonable searches.

"These types of broad geofencing warrants that are asking for large areas without being able to particularize where specifically they're looking," said legal analyst Karen Steinhauser. "Those are the ones that are getting struck down."

In this case, investigators had not only specific locations but times in remote areas -- and that, Steinhauser says, means the courts are more likely to allow it as evidence if the case goes to trial.

In addition to the cellphone data, investigators said they got a flurry of tips, including from people who reportedly heard the suspects themselves talking about the incident.

A tipster told investigators Koenig "frequently participates in destructive behavior" and when asked why, Koenig said "he likes creating chaos." That same person told investigators that some of the suspects went to a Walmart parking lot where "as many" rocks "as they could carry" were loaded into the bed and back seat of the cab.

After the suspects were taken into custody, investigators say Karol-Chik told them the route they took on the day of the deadly rock throwing, which police say lines up with what the cellphone location data shows.

Karol-Chik also allegedly told investigators that Koenig was driving and Kwak was doing the throwing. After Kwak allegedly threw the rock that hill Bartell's car, Kwak said to the others in the truck, "we have to go back and see that." Investigators said there was an emphasis on the word "have."

Kwak also admitted to investigators that he threw the rocks as Koenig drove and Karol-Chik called out the locations of other cars on the road, according to the arrest affidavits. Kwak said Karol-Chik used "Marine" terms, such as "contact left," indicating a car to the left side of their own vehicle.

After the rock hit Bartell's car, Kwak said Koenig turned around and Kwak took a picture of Bartell's car. He allegedly told investigators that one of them might want it for a memento.

Koenig declined to talk to investigators, they said.

Thursday was the suspects' first appearance, which means the judge will typically decide whether to set bail and at what amount, and then set the next hearing date.

After the suspects were arrested and identified, CBS News Colorado spoke to neighbors.

"As a mom, to hear somebody's child that is catastrophically and unexpectedly injured and taken so abruptly, and then having it linked to your neighborhood, in your school -- it's heartbreaking," one neighbor, who asked not to be identified, said.

That neighbor says she was not surprised to learn Koenig was involved.

"Unfortunately, it wasn't a shock when we found out that Joe was one of the people accused of this incident," she said. "There had been discussion and concerns in the neighborhood for actions he had taken in his past."

Kwak reportedly attended prom over the weekend, posting on his Instagram just before being arrested.

Each of the three suspects is now charged with first-degree murder with extreme indifference.

"To be clear about what 'extreme indifference' is, it's described as an attitude or behavior that exhibits indifference about what they are doing - in this one, it's respect to human life," said Jacki Kelley, a spokesperson for the Jefferson County Sheriff's Office.

The suspects are due back in court Wednesday to face formal charges.

Additional Information from the Jefferson County Sheriff's Office about the Alexa Bartell Memorial Fund:

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.

Donations can be made directly to the Alexa Bartell Memorial Fund at FirstBank.

Donations are also accepted via Zelle @ alexabartellmemorial@gmail.com

Donations are also accepted via Venmo @Alexa-Bartell-4 or the QR code below.