DENVER (KDVR) — Authorities are releasing new details into the deadly shooting of a man during dueling protests in downtown Denver on Saturday. The alleged shooter, working as a 9News security guard, was not licensed to work as a guard in Denver.

Lee Keltner, 49, who was shot and killed, was with his 25-year-old son during the rally. Court documents state father and son walked from Civic Center Park toward the Denver Art Museum before things turned violent Saturday afternoon. Verbal altercations among multiple people led to the deadly shooting in a fog of pepper spray, according to police.

The probable cause affidavit for arrest revealed Denver police were joined by officers from the Arapahoe and Douglas County sheriffs’ offices when unlicensed security guard Matthew Dolloff, 30, was arrested.

Police say, while walking, Keltner and a man started arguing.

“Both men yelled and postured, leading several witnesses … to believe the men may engage in a physical altercation,” the affidavit read.

Police said a witness stepped between Keltner and that man — urging both to stop. Video evidence then shows another man and Dolloff involved in an altercation with Keltner, according to the affidavit.

Keltner is then seen striking Dolloff on the side of his face with an open hand. Dolloff then allegedly pulled a gun from his waistband. Images show Dolloff aiming at Keltner. Police said Dolloff fired once, striking Keltner as Keltner discharged pepper spray. Keltner then collapsed to the ground.

Officers quickly arrested Dolloff, the affidavit states. Police said Keltner was pronounced dead about 30 minutes later at Denver Health Medical Center.