As authorities investigate the police killing of Rayshard Brooks, which led to the police chief’s resignation, protests and the torching of a Wendy’s, two former law enforcement officials said the shooting was not justified while a police union president called it “legitimate.”

Cedric Alexander, the former police chief of DeKalb County, east of Atlanta, said the Friday night encounter outside a Wendy’s restaurant should never have escalated into a use-of-force situation.

Alexander suggested the officers who found Brooks, 27, asleep in his car in the restaurant’s drive-through could have called him an Uber or given him a ride home instead of taking him into custody.

“Could they have done something different than arrest him?” he said. “We need to get policing back to doing preventative enforcement. That’s the key.”

Body and dash camera footage show that the officers, Garrett Rolfe and Devin Brosnan, were attempting to arrest Brooks after he failed a sobriety test. The incident quickly escalated when Brooks insisted he could walk home. As the officers began taking him into custody, they struggled with Brooks.

Surveillance footage appears to show Brooks running away from the officers with a stun gun that he had taken from one of them, said Vic Reynolds, director of the Georgia Bureau of Investigation. While running, Brooks appeared to turn around and point the weapon at police, Reynolds said.

“At that point, the Atlanta officer reaches down and retrieves his weapon from his holster, discharges it, strikes Mr. Brooks there on the parking lot, and he goes down.”

Rolfe was fired Saturday after Mayor Keisha Lance Bottoms said in a news conference that she did not believe the shooting was justified.

But Steven Gaynor, a police union president in suburban Atlanta, said he believed the shooting was “legitimate.” A stun gun in the hands of someone who isn’t trained to use it can be lethal, he said.

“If I’m an untrained individual and I aim it at your head, that could be deadly,” he said. “You could lose an eye.”

Reynolds has said he did not know what the range was of the stun gun that Brooks had taken.

A lawyer for Brooks’ family, L. Chris Stewart, said over the weekend that Georgia law does not consider a stun gun to be deadly.

But a 2017 Reuters investigation found that such weapons can be lethal even in the hands of someone trained to use them. It found that roughly 1,000 people have died since the early 2000s after police struck them with a stun gun. In 153 of the cases, autopsies concluded the weapon had caused or contributed to the person’s death.

Stun guns, which can sometimes deliver up to 50,000 volts in a single shot, can cause serious problems for people with heart conditions and other medical issues. In a 2016 study, researchers compared the short-term cognitive impairments caused by the weapon to dementia.

Gaynor said a Georgia officer’s ability to use force, as taught in the Atlanta police academy, operates on a continuum. If Brooks tried to use the stun gun on Rolfe, then the officer’s actions meet the criteria for the next step on the continuum, he said.

The GBI has said Brooks pointed the stun gun at the officer.

“You have the right to use one step above to protect your life or the lives of others,” Gaynor said.

But Joe Ested, a former law enforcement officer and founder of the nonprofit Police Brutality Matters, said an officer must see imminent danger either to himself or someone else for deadly use of force to be justified.

“When we look at this, the video, you see the subject running away,” he said. “There’s no life at risk at that time — at all.

“Even a subject running away that has a weapon — unless the weapon the subject has results in death, you still are not able to authorize the use of deadly force.”