MEMPHIS (AP) — No criminal charges will be brought against a Memphis police officer who fatally shot a Black man after a high-speed chase and an attempted traffic stop, the top state prosecutor in the city said Tuesday.

Shelby County District Attorney Steve Mulroy said his office's Justice Review Unit looked at evidence in the shooting of 20-year-old Jaylin McKenzie and concluded Officer Nahum Dorme should not be charged.

Memphis police had said officers out on patrol on Dec. 16 saw a suspicious car and tried to stop it, but the driver sped off before losing control and driving into a park. McKenzie and three other Black men ran from the vehicle, and all of them had guns, authorities said.

Officers went to chase one of the fleeing men, who then shot at the officers, authorities said. One officer, identified as Dorme, fatally shot the suspect. The Tennessee Bureau of Investigation started looking into the shooting.

During a news conference Tuesday, Mulroy said he sent a letter to Memphis Police Director Cerelyn "CJ" Davis informing her that Dorme, who is Black, and four other officers involved in the incident that led to McKenzie's shooting would not be charged.

Police video showed McKenzie was holding an assault rifle when he was first confronted by officers and disobeyed orders to stop running away, Mulroy said. McKenzie dropped the rifle, but he fired a handgun twice at officers, he said.

Because Dorme, the officer who shot McKenzie, did not have his body camera on, "we have no evidence to contradict his claim that Mr. McKenzie fired first and that he fired in self defense," Mulroy said.

The DA said he did tell the police chief in the letter that he was concerned about the way the shooting was handled by officers. Dorme and his partner violated department policies by conducting a high-speed chase for running a red light with a patrol car siren that was not on, Mulroy said. A supervising officer also failed to separate Dorme and his partner after the shooting.

"Instead, he deliberately placed them in the same patrol car by themselves for several hours," Mulroy said. "This allowed them to discuss the facts of the case together, in violation of MPD policy."

Mulroy said there were "material discrepancies" among the officers' statements about the shooting and the video.

Some of these issues have been part of internal discussions by the police department, the DA said.

"Taken together, this does raise significant concerns about MPD officer conduct in these types of shootings," Mulroy said.

In a statement, Memphis police said neither Dorme nor his partner, Officer Christopher Jackson, told their immediate supervisor about the pursuit after it started nor activated the patrol car's siren.

Dorme and Jackson received written reprimands for violating the department's vehicle pursuit policy, and Dorme was given another written reprimand for failing to turn on his body camera, police said. The first responding supervisor, Lt. Mark Gilbertson, received a spoken warning for failing to separate the two officers after the shooting, police said.

McKenzie's shooting happened a few weeks before Tyre Nichols was fatally beaten by five Memphis officers after a traffic stop in January. Nichols was Black, as are the five officers. The beating was caught on video that was released to the public. The five now fired officers have been charged in state court with second-degree murder, and by a federal grand jury with civil rights violations in Nichols' death. They have pleaded not guilty to all charges.

The U.S. Justice Department said in July it is investigating the Memphis Police Department's use of force; how it conducts traffic stops, searches and arrests; and whether it engages in discriminatory policing.

McKenzie's mother, Ashley McKenzie Smith, and activists had held rallies and called for criminal charges to be brought in his shooting. Jaylin McKenzie lived in Atlanta with his mother, and he was in Memphis visiting his father when he was killed.

Jennifer Cain, a spokesperson for McKenzie's mother, said her supporters were disappointed and disturbed by the decision not to charge Dorme.

"It's very disturbing that a killer is still walking around the streets of Memphis," Cain said. "We are just trying to cope with the decision."