A former San Francisco rookie police officer who killed an unarmed Black man just weeks into the job has been charged in connection to the death.

The charges are believed to be the first prosecution of a cop in connection with an on-duty killing in the city's history, authorities said Monday. 

District Attorney Chesa Boudin announced that Chris Samayoa will face charges of voluntary manslaughter, involuntary manslaughter, assault by an executive officer, assault with a semi-automatic firearm and negligent discharge of a firearm in connection to the Dec. 1, 2017, death of 42-year-old Keita O’Neil.

"In San Francisco there has been a long history of officer-involved shootings leading to no accountability whatsoever, further cementing the idea that police are above the law,” Boudin said during a news conference. “That stops today.”

Samayoa is expected to surrender to authorities this week. Boudin said his office will not seek to hold him in jail pending trial because Samayoa is not believed to be a flight risk. 

Samayoa killed O'Neil during a chase after O'Neil allegedly stole a California State Lottery van. The rookie officer and his field training officer were in a patrol car chasing O'Neil when the officer allegedly fired a shot through the passenger window of the moving police cruiser.

Authorities said O'Neil was running near the vehicle when he was shot in the head and died at a hospital.

The shooting was recorded by a police body-camera. Samayoa was fired from the police force shortly after the shooting. 

April Green, O'Neil's aunt, said the charges were welcome news.

"I am happy to hear this news, and hoping it brings some justice to our family," she said in a statement released through Boudin's office. 

Body-camera footage captures when former officer Chris Samayoa allegedly fatally shot 42-year-old Keita O’Neil during a 2017 chase. (San Francisco Police Department )

Supervisor Shamann Walton, whose district includes the area where O'Neil was killed, said the prosecution shows that "Black lives matter and that unlawful police violence will not be tolerated."

The San Francisco Police Officers Association did not respond to a Fox News request for comment. 

O'Neil's family has filed a lawsuit against the city over the killing. 

The charges are historic given that no San Francisco police officer has been prosecuted for an on-duty killing, Boudin said. The shooting occurred before he was elected to office. 

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His candidacy was fiercely opposed by local law enforcement officials because of his family ties to police killings. Boudin's parents were part of the radical left-wing Weather Underground who served as getaway drivers during a botched 1981 heist in New York that left two officers and a third person dead. 

He grew up with his parents incarcerated. 

Boudin, who worked as a public defender before becoming the city's top prosecutor, ran on a platform of criminal justice reform and taking a tougher stance on police misconduct.