(CNN) The two police officers who were involved in a fatal shooting last summer in Anaheim, California, will not face any criminal charges, the police chief said Wednesday.

Sean Staymates and Kevin Pedersen fired more than 70 times at 50-year-old Eliuth Penaloza Nava, who they'd been told was armed and acting erratically, according to authorities.

"It is our legal opinion that there is a lack of sufficient evidence to show beyond a reasonable doubt criminal culpability on the part of Officers Staymates and Pedersen when they fatally shot Nava on July 21, 2018," the Orange County District Attorney's Office said in a letter to Anaheim Police Chief Jorge Cisneros, providing details of the investigation.

"Both Officer Pedersen and Officer Staymates were justified in believing that Nava posed a significant threat of death or serious physical injury to both officers and to others," the letter said. Even though they weren't charged, the DA's letter called their conduct "alarming and irresponsible."

Neither Pedersen nor Staymates could be reached on Wednesday.

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