The Denver District Attorney announced Thursday that a Denver police officer who fatally shot a man brandishing a BB gun in April used justifiable deadly force.

The shooting happened just before 5 p.m. on April 7 in the 1000 block of South Quitman Street. Police responded after a 911 call was placed, reporting a man pointing a firearm at people.

When officers arrived, they saw a man, later identified as Joseph Frank Martinez, 58, armed with what appeared to be a rifle in a backyard. For more than an hour, Martinez engaged in a standoff with police, who attempted to convince him to put down the gun and surrender, but Martinez refused.

Martinez was fatally shot by Denver police technician Anthony Vessa after Martinez raised his firearm at Vessa and ignored commands to drop it. Police later determined Martinez’s firearm was, in fact, a BB gun.

Denver DA John Walsh wrote in his decision that Vessa had reasonable grounds to believe Martinez was armed with a real weapon.

“After reviewing the facts contained in the investigation of this shooting, I find that Technician Vessa had objectively reasonable grounds to believe, and actually did believe, that he was in imminent danger of being killed or receiving serious bodily injury from Martinez,” Walsh said.