SAN DIEGO -- A patrolman was legally justified in fatally shooting a homeless man who advanced on him with a steak knife on his hand in a Gaslamp District intersection last summer, District Attorney Bonnie Dumanis concluded in a ruling released Thursday.

San Diego police Officer Christopher Leahy opened fire on 48-year-old Phillip James Sewer at Fourth Avenue and E Street after the transient ignored repeated commands to halt and drop the weapon on the afternoon of Aug. 3, according to Dumanis.

Sewer, who minutes earlier had stolen the knife from a nearby restaurant and threatened several employees, was struck by three bullets and died at the scene.

Leahy, his patrol partner and at least eight passers-by told investigators Sewer was behaving in a belligerent and irrational manner, refused to cooperate with police and repeatedly screamed at them to shoot him, the district attorney wrote in a letter to SDPD Chief William Lansdowne.

An autopsy determined that Sewer had a blood-alcohol level of 0.18 -- more than twice the legal limit for driving -- at the time of his death.

Under California law, peace officers are entitled to use lethal force to protect themselves and members of the public from threats of great bodily injury or death, Dumanis noted.

Leahy, 28, shot Sewer after the knife-waving transient closed the distance between them to about five feet, she stated in the legal analysis.

"Based on these circumstances, it's readily apparent that Officer Leahy fired in self-defense, and he therefore bears no criminal liability for his actions," Dumanis wrote.