SACRAMENTO, Calif. (AP) — A former police officer already imprisoned for one fatal shooting in a wealthy San Francisco suburb won’t face criminal charges in a second slaying, this one of a homeless Black man who asked the officer to kill him during a 30-second confrontation, a prosecutor said Friday.

Contra Costa District Attorney Diana Becton said she won’t seek to try former Danville officer Andrew Hall in the death of Tyrell Wilson, who was holding a knife at the time of their confrontation in March 2021.

Hall already is serving a six-year prison sentence in the fatal shooting in 2018 of Laudemer Arboleda, 32, during a slow-speed police chase. Hall was convicted last year of assault with a firearm for firing into Arboleda’s vehicle as it passed by him. Arboleda, who was unarmed and mentally ill, was hit by nine bullets as he drove away from police.

Becton said she did not have evidence beyond a reasonable doubt that Hall, 33, acted illegally when he killed Wilson last year while responding to reports of a person throwing rocks from an overpass onto a highway.

She called it “a difficult and challenging case” and that she and her legal team “spent a considerable amount of time and resources evaluating the evidence before coming to this conclusion.”

“As a community, we need to find ways to de-escalate law enforcement encounters where the use of force leads to tragic outcomes,” she said in a statement. “The loss of Tyrell Wilson’s life weighs on our community and I express my deepest condolences to the Wilson family.”

An attorney for Hall, Harry Stern, did not immediately respond to telephone and email messages seeking comment.

Becton has been criticized for taking two years to investigate Arboleda’s death, leaving Hall on duty long enough to be involved in the second fatal shooting. Becton filed the charges one day after a jury convicted Minneapolis police Officer Derek Chauvin of killing George Floyd.

Had she charged Hall more quickly in the earlier shooting, “this never would have happened,” said John Burris, an attorney for Wilson’s family. “This young man would not have been killed.”

Critics have also questioned whether race played a factor: Hall is white, Wilson is Black, and Arboleda of Filipino descent. Danville is a town of multimillion-dollar homes and predominantly white residents.

Video taken by a nearby motorist showed Hall standing feet away and facing Wilson before the officer appeared to move toward Wilson, as Wilson appeared to step backward. The motorist’s video doesn’t appear to show Wilson make any sudden moves toward Hall.

Becton’s office said that before the shooting Wilson told Hall not to touch him, then took a folding knife from his jacket and held it by his right thigh, the blade pointing forward. He took five steps away from Hall while saying twice, “Touch me and see what’s up.”

Hall drew his gun and pointed it at Wilson, telling him to drop the knife three times. Wilson then took two to three steps toward Hall, raised the knife to his chest, looked up at the sky and said “Kill me,” according to the report by Becton’s office.

Hall took about three steps backward and shot Wilson once in the head, firing just 32 seconds after he first spoke to Wilson. Wilson died at a hospital two days later.

Police previously released still photographs showing Wilson holding a bag in his left hand and a folding knife in his right hand.

A juror could reasonably conclude that Hall was in imminent danger, particularly if Wilson was “potentially engaging in ‘suicide by cop,’” Becton’s report concluded.

Burris said in his view “there was sufficient evidence to justify prosecution here.”

Wilson suffered from schizophrenia and Burris said he was obviously mentally impaired when Hall approached him.

“That should have been a clue right then that there was something going on with this young man,” Burris said.

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“But the officer didn’t back up and reassess. He became very aggressive,” Burris said. “The officer created this confrontation.”

He said the family could ask the state attorney general or U.S. attorney to review the case, noting that California law requires that police killings not only be reasonable, but necessary. Wilson’s death doesn’t appear necessary, given the circumstances, Burris said.

Becton charged Hall with manslaughter and assault in Arboleda’s death a month after he fatally shot Wilson, but a jury deadlocked on the voluntary manslaughter count while convicting him of assault.

Hall is serving his six-year sentence at nearby San Quentin State Prison.

The Contra Costa Sheriff’s Office provides police officers to Danville under a contract, and the county has paid more than $9 million to the families of the two slain men to settle civil rights lawsuits. The sheriff’s office had cleared Hall of misconduct into Arboleda’s death after its own nine-month investigation.