CHARLOTTE, N.C. — A citizens review board studying a police shooting that led to two days of riots in North Carolina’s largest city is recommending the police force conduct a scientific study into the reaction time of officers.

Charlotte-Mecklenburg Police released that recommendation and two others Friday in what Police Chief Kerr Putney said was an ongoing effort to be as open as possible about the killing of Keith Scott last September.

Putney promised to bring in a third-party group to do a scientific study to verify the police department’s own research that a suspect can usually pull a gun from his side and shoot an officer before the officer can react.

The chief said he will take two other recommendations under consideration. The review board suggested reviewing the department’s surprise takedown tactics for people in vehicles and said police should look for more non-lethal ways to deal with armed suspects.

“A gun is a game changer,” Putney said, explaining why those recommendations needed more review.

Keith Scott was shot and killed Sept. 20, 2016, after an officer saw him with marijuana and a gun, sitting in a SUV in an apartment complex waiting for a child to get off the school bus. The officer who killed Scott said he was looking for another person who faced an arrest warrant when he saw the drugs and the weapon. A prosecutor did not charge the officer.

The review board seemed concerned that never in any video footage of the shooting did Scott point the gun at officers and that the sudden movement of police vehicles and officers to block Scott in and break the window when he didn’t respond might have escalated the situation to a fatal shooting.

But once officers see a gun in or near a suspect’s hands, non-lethal solutions like Tasers, pepper spray or even reasoning with the suspect are limited because they don’t know what is in the person’s mind, Putney said.

“You put the gun down, I’m going to talk your ear off,” the chief said.

Scott’s shooting led to two days of unrest, with looted stores near the scene and in downtown Charlotte, millions of dollars of damage, a fatal shooting and more than two dozen injuries to police officers and others.

Putney said he hopes the anniversary of the shooting is met with somber reflection or lawful protests.

“As a community, we went through a lot last fall,” Putney said. “I don’t want that missed in all this legalese.”