Three high school seniors were arrested and accused of hurling a landscaping rock at a Colorado woman, killing her as she drove just outside Denver, authorities said Wednesday.
Alexa Bartell, 20, "was killed when a rock was thrown through her windshield as she was driving" north in the 10600 block of Indiana Street about 10:45 p.m. in Westminster on April 19, Jefferson County sheriff's investigators said in a statement.
Bartell's was the last of several cars "struck by large landscaping rocks in a spree that began shortly after" 10 p.m. near 100th Avenue and Simms Street, officials said.
Tips from the public and cellphone data played key roles in finding the suspects and making the arrests, sheriff’s spokesperson Jacki Kelley told reporters.
"This case touched a lot of people deeply," Kelley said. "This was a beautiful young woman with her whole life in front of her who was simply driving home, and her life was ended as a result of these acts. It was shocking to a community, and people wanted to find out who was involved."
All three are 12th graders in Jefferson County Public Schools, Kelley said. One attends Ralston Valley High School, another goes to Standley Lake High School, and a third is enrolled in an online program, she said.
A representative for the school district couldn’t immediately be reached for comment Wednesday.
Two suspects were arrested at 10:59 p.m. Tuesday and a third at 2 a.m. Wednesday, Kelley told reporters. They were all living with their parents.
Sheriff's investigators called Bartell's family in the middle of the night to notify them of the arrests.
"They're just grateful," Kelley said. "They're still suffering the greatest loss possible."
The rock is what killed Bartell and not any subsequent crash, which took place about 20 miles northwest of Denver and 10 miles southeast of Boulder, officials said.
"The rock came through Alexa Bartell's windshield, striking and killing her," Kelley told NBC News on Wednesday. "The rocks that we have described in this crime series are all about 4 to 6 inches in size and about 3 to 5 pounds apiece. They're large boulder landscaping rocks."
The suspects were traveling in a black 2016 Chevy Silverado; it wasn’t immediately clear who was driving or who threw the rock that killed Bartell, officials said.
"We believe the vehicle was traveling in the opposite direction as our victims," Kelley said.
The three suspects were booked on suspicion of first-degree murder by extreme indifference, the sheriff said.
While first-degree murder is typically associated with an intended victim and a motive, Colorado’s extreme indifference statute is meant for defendants who aimed to kill someone — not just a targeted individual, University of Colorado clinical law professor Ann England said.
“Pulling out an AK-47 and shooting into a crowd of people, then there’s no doubt that you intended to kill,” even if you were not targeting a specific person, England said.
“Throwing a rock (and charging first-degree murder) is going to be hard. I mean is throwing a rock a known risk (to possibly kill someone)? Throwing a rock at a moving car, now that someone has died, it seems obvious, right? But before that? I’m not totally sure.”
It was not immediately clear whether the three men had hired or been assigned lawyers to speak on their behalf.
Phone calls to publicly listed phone numbers for Colorado relatives of Koenig, Kwak and Karol-Chik went unanswered Wednesday.
The three teens were expected to make their first court appearance Thursday morning.
Kelley said she can recall individual cases of rocks or bricks being tossed off bridges over the years in Colorado but never a series of such reckless acts.
"These suspects went from place to place to place to place throwing large rocks through windshields of moving vehicles. We’ve not seen it before."
This article was originally published on NBCNews.com