The slaying of Stephon Clark, 22, was the latest in a long string of fatal shootings of black men by police officers that have raised questions about race and justice in the United States and fuelled the Black Lives Matter movement.
"Due to the nature of this investigation, the extremely high emotions, anger and hurt in our city, I felt it was (in) the best interest of our entire community ... to ask the attorney general to be an independent part of this investigation," Sacramento Police Chief Daniel Hahn, the department's first black leader, said at a news conference.
Local Black Lives Matter leaders said they were unimpressed by the move and planned a protest at the Sacramento County District Attorney's Office to call for the investigation to be conducted by the city's civilian Community Police Review Commission.
"The community needs to be the one that leads the investigation," Tanya Faison of the Sacramento branch of the Black Lives Matter movement said at a separate news conference.
Two Sacramento officers, responding to a report of someone shattering car windows, shot Clark in his grandparents' backyard the night of March 18. Clark was holding an object the officers believed was a firearm, but after he fell they only found a cell phone by his body, police said.
"We fully expect that the California Attorney General's Office will do a complete and thorough investigation that is fair and impartial," Benjamin Crump, the family's attorney, said in a statement.
California Attorney General Xavier Becerra said state investigators will act independently while overseeing the investigation, and will also review the Police Department's procedures and practices.
Sacramento police have not released the names of the two officers who opened fire, citing concerns about their safety. One officer is white and the other is black, and they both have been placed on leave, police said.
(Reporting by Peter Szekely in New York and Alex Dobuzinskis in Los Angeles; Editing by Dan Grebler and Matthew Lewis)