'Signature crack-and-pop': Expert says Charlie Kirk likely killed with supersonic bullet

Charlie Kirk, founder of Turning Point USA and confidant of President Donald Trump, was slain by a bullet traveling at supersonic speeds, according to a report.

Kirk was killed by a single gunshot while speaking at a public event at Utah Valley University on Wednesday. Authorities have called it a politically motivated assassination and said the sniper likely fired from a rooftop about 200 yards away.

CNN reported Thursday, citing an audio forensics expert, that audio recorded near the podium where Kirk was speaking indicated he was struck by a bullet traveling faster than the speed of sound, which is typically around 1,100 feet per second.

Culturally-related phrases were also scrawled on a rifle and ammunition recovered by authorities, CNN reported.

"Audio analysis does capture a signature crack-and-pop pattern in the video," senior investigative correspondent Kyung Lah told CNN's Anderson Cooper late Thursday. "It is a little hard to hear unless you really slow it down. And that, says audio forensics expert Rob Maher, is a single supersonic gunshot."

She added that supersonic rounds are fired from high-powered rifles, which ruled out the possibility that a small handgun was used, as they fire below the speed of sound.

"Omar's analysis does find that, based on the time between that crack-and-pop sound and an inferred bullet speed, the firearm would have been located about 150 meters from where Kirk was using that podium," she added.