San Francisco Police Chief Bill Scott on Friday fired the rookie cop who, four days into his police career, shot dead an alleged carjacker. In return, the police union fired back a fusillade of its own, accusing Scott of cowardice and political expediency.

Other officers — who would not speak on the record for fear of retribution from the police union — told Mission Local they backed the chief. One emphasized that cops must be held accountable for failing to follow procedures, including warning someone before shooting, and firing through a closed window.

These are both directives Officer Chris Samayoa failed to follow. On Dec. 1, Samayoa — in just his first week in the job — was the passenger in his training officer’s squad car as they pursued Keita O’Neal into the Bayview. The 42-year-old was suspected of violently carjacking a van from a California Lottery official and leading the police on a serpentine chase. The pursuit came to a close on a dead-end street, at which point O’Neal, who was unarmed, leapt from the vehicle and ran beside the trailing police car.

Without lowering the window or shouting a warning, Samayoa killed O’Neil with a single shot to the head, an act that was caught on his body camera.

The SFPD confirmed that, on Friday, March 9, Scott “released” Samayoa — an act he is allowed to undertake unilaterally and for any cause, as the rookie was still in his probationary period.

Calls and messages for Scott have not been returned. The San Francisco Police Officers Association (POA) on Monday assailed Scott in an e-mail to its membership, in the latest visceral denigration of the chief.

“We have been bewildered by this chief since he came here. He makes no attempt to visit the troops, no attempt to go to stations. He’s very aloof, very distant,” bemoaned Gary Delagnes, the POA’s longtime president turned consultant. “The chief was party to this termination for purely political reasons. The victim was African American and this was the easy way out.”

Samayoa is described by the POA as a “Hispanic who grew up in the Mission.”

He “is a textbook example of what an officer should be,” read the POA’s letter to its unionized workforce. “Chris is an exemplary human being.”

Samayoa, per the POA, is a fluent Spanish speaker who graduated from Riordan High in 2008 and the University of Arizona, and put his master’s at USF in counseling and psychology on hold to join the department. He worked at the Edgewood Center with troubled foster youth and as a case manager with homeless families, according to the POA.

A number of police use-of-force experts, however, told Mission Local, the officer’s actions were troubling.

Several noted that, when Samayoa fired the fatal shot, his fellow officers had yet to even draw their weapons.

“That the training officer walks around and his gun is not out, it tells us something — it could suggest he did not perceive a threat,” Seth Stoughton, a professor at the South Carolina School of Law and a former police officer, told Mission Local in January. “If he did perceive an ongoing threat, his gun would be out and he would be cornering around the car more carefully than he does.

“Even if a guy was shot, you do not take for granted that he is not a threat anymore,” Stoughton continued. “Proceed cautiously. I didn’t see that type of cautious tactical approach when the training officer just walked around.”

David Elliot Lewis, who served for four years as a trainer on the SFPD crisis intervention team, also raised questions about the officer’s actions. “Officers are supposed to shoot to protect life,” he said. “I don’t know who they were protecting.”

Scott is entitled to fire Samayoa unilaterally, as he was just four days into his 12-month probationary period. Had he been a veteran officer, axing him would have required the Police Commission to act upon the recommendation of the chief.

As an at-will employee, however, Samayoa’s options are more limited. “He has no recourse, really,” sums up Delagnes. He can demand a “Lubey Hearing,” as a dismissed probationary employee but, “he will most certainly lose,” the union honcho continues.

Samayoa, Delagnes notes, is currently huddling with the POA to decide whether to file a writ with San Francisco Superior Court, to win back his job of four days.