JEFFERSON COUNTY, Colo. (KDVR) — More information is surfacing about what led to the arrest of three high school seniors suspected of a rock-throwing crime spree that killed a 20-year-old woman.

Arrest documents obtained by KDVR on Thursday outlined what led to the arrest of Joseph Koenig, Nicholas “Mitch” Karol-Chik and Zachary Kwak.

Timeline of investigation

According to the documents from the Jefferson County court, investigators located a camera near one of the incidents that showed three vehicles, one of which was driven by a victim and another driven by a witness. The only other vehicle on the road was tracked between multiple cameras and moving at a high speed, the affidavit showed.

Investigators said they sent photos of the taillights to a Chevrolet employee. The vehicle was identified as a 2014-2016 Chevy Silverado pickup.

On Tuesday, a person called police to explain that he and a coworker were talking about the rock-throwing incident. The coworker said that on April 19, he was with three people who were loading rocks into their vehicle at a Walmart parking lot.

The coworker then said he asked to be taken home because he didn’t want to have anything to do with what they were up to, documents showed.

Where did the rocks come from?

According to investigative documents, police interviewed the coworker as a witness and he told them that he watched people named Joe, Mitch and Zach take landscaping rocks from the edge of the Walmart parking lot on April 19.

He also said they put the rocks in the back seat of a Chevy Silverado 1500 pickup truck, possibly around a 2019-2020 model, court documents showed.

When investigators asked how many rocks they took, the witness said, “As much as they could carry.”

The witness told investigators he “knew something bad was going to happen,” so he insisted they take him home, which they did, the court documents showed.

When they left, Joe was driving, Mitch was in the front passenger’s seat, and Zach was behind Mitch, according to the witness.

Other rock-throwing incidents

When Mitch, identified as Nicholas “Mitch” Karol-Chik, was arrested Tuesday, he agreed to speak with investigators.

According to police documents, Karol-Chik told investigators that all three were involved in throwing rocks at moving cars and that he and Zachary Kwak collected the rocks.

Karol-Chik also allegedly told investigators that he and Joe Koenig were involved in throwing objects, including a statue and other rocks, at vehicles since at least February and at least on 10 separate days.

Karol-Chik also alleged that Koenig threw the rock that hit Alexa Bartell‘s vehicle, resulting in her death.

Investigators said when Koenig was arrested, he declined to be interviewed.

When Kwak was arrested, he did, however, agree to be interviewed. According to court documents, he told investigators he was with Koenig and Karol-Chik and they went to a Walmart near Denver and then went driving around.

Kwak allegedly said he remembered stopping to collect rocks and then throwing them at passing cars. He said he believed Koenig was driving.

He also explained that Koenig threw the final rock, which was the one that hit Bartell’s car. Kwak said he saw the car leave the road and shortly after, Koenig turned around and went back to where it happened. When they got there, Kwak said he took a picture of the vehicle because he thought Koenig or Karol-Chik would want it as a memento, documents showed.

Kwak allegedly told investigators, they left after that, and Koenig took him home. During the drive to Kwak’s house, he allegedly said Koenig and Karol-Chik were talking about them now being “blood brothers” and they could never speak of the incident.

According to investigators, Kwak said Koenig met with him the next day to get their stories straight about what happened and tried to deny involvement.

What charges are they facing?

All three suspects are facing charges of first-degree murder with extreme indifference. Additional charges are expected to be filed at a later date.

They are being held without bond.