JEFFERSON COUNTY, Colo. (KDVR) — Teens who said they knew at least one of the suspects arrested and charged with throwing rocks at cars spoke with FOX31 about the 18-year-old.

The crime shocked a community that demanded justice, especially for Alexa Bartell, who was killed driving on a road in Jefferson County when a rock was thrown at her car last Wednesday.

Two teens told FOX31 they knew one of the suspects in the case, Zachary Kwak.

“I found it semi-believable. It was something that he probably would have done, because he had stupid ideas,” one teen said at a skatepark in Arvada.

They said he was known for being a trickster to get people talking.

“He just would always mess around and just want to be funny and have that attention on him,” another said.

Technology helped pinpoint rock-throwing suspects

Former district attorney and FOX31 legal analyst George Brauchler gave insight into how investigators may have pinpointed the suspects through their mobile phones.

“Who was where, when,” Brauchler said, “and match that up with the reports of cars getting hit with rocks.”

Brauchler said one factor likely helped investigators.

“(It’s) incredibly helpful that it happened repeatedly over a short period of time,” Brauchler said.

That period of time was a window, Brauchler said, for investigators to cross-examine cell tower data and geo-point them to the suspects.

“I just spoke with the chief of police for Aurora about a case handled back in Florida some years ago,” Brauchler said. “It took them a year to close. This moved very, very quickly, and I think technology’s to thank for it.”

Time is a very important factor in this case, according to Brauchler, even the time we live in.

“These are things that might not have been around 20, 25 years ago, not the way they are today,” Brauchler said.

FOX31 did a background check on all three suspects in this case, finding no criminal record for Kwak and Joseph Keonig. Nicholas Karol-Chik has one count on his record for speeding.