DENVER (KDVR) — The District Attorney’s office will be dropping charges against a security guard accused of shooting and killing a man during the “Patriot Muster” in downtown Denver in the fall of 2020.

Denver District Attorney Beth McCann plans to dismiss the charges at the pre-trial conference scheduled for March 21, according to the security guard Matthew Dolloff’s attorney Doug Richards.

“In line with our ethical obligations, we cannot overcome the legal justifications of self-defense or defense of others. We are not able to prove guilt beyond a reasonable doubt,” the DA’s office said.

Dolloff was working for 9News to protect its journalist during protests when he shot and killed Lee Keltner during a confrontation. Records show Dolloff did not have the license required to work as a security guard in the city of Denver.

Photos from the event show Dolloff and the victim, Lee Keltner, facing off before the deadly shooting. According to the police narrative, Keltner had been involved in an argument with another man and at one point turned his attention toward Dolloff. Keltner hit Dolloff in the face and then within seconds discharged OC spray while Dolloff simultaneously fired one shot.

This is a developing news story. Check back for more breaking details.