Updated

Prosecutors say criminal charges won't be filed against a California police officer who killed a mentally unstable black man he thought was aiming a gun.

San Diego County District Attorney Bonnie Dumanis announced Tuesday that her office determined the shooting of 38-year-old Alfred Olango last September was justified because the officer thought his life was in danger.

Video showed Olango in a shooting stance, with both hands wrapped around a cylindrical object that turned out to be an e-cigarette device.

The shooting in El Cajon prompted days of demonstrations and Olango's relatives filed wrongful-death claims with the city. They said the Ugandan native had a breakdown after a friend's death.

Olango was shot as police answered calls from Olango's sister saying he was acting erratically and needed mental health care.