The dashboard camera video shows what appears to be a routine traffic stop -- until it is not.
Experts who spoke with the Los Angeles Times were struck by how courteous the initial exchange was between North Charleston, S.C., Police Officer Michael T. Slager and motorist Walter L. Scott.
They agreed that Scott should not have run, but disagreed about whether Slager should have chased him. And they noted that when Slager shouted, "Taser! Taser! Taser!" it meant he was about to use the non-lethal weapon.
In the video, released Thursday by the South Carolina Law Enforcement Division, Scott pulls into a parking spot at an Advance Auto Parts store in North Charleston. Moments later, Slager walks toward the car.
"The reason I stopped you is your brake light is out," Slager says. He asks for Scott's license and registration.
Scott says he doesn't have the registration or insurance card because he is in the process of purchasing the car, but he appears to hand Slager his driver's license. The officer takes it to his police cruiser, telling Scott to wait inside his own car.
A few minutes later, however, Scott gets out and runs away. A cellphone video taken by a passerby picks up the encounter, apparently as Slager is trying to use his Taser on Scott. That video shows Slager firing eight shots at a fleeing Scott, who is killed.
Slager is charged with murder.
But how did everything go so wrong? Neither man raised his voice nor made any move toward the other. Neither appeared hostile.
"I was a bit surprised at how courteous [the officer] was," Terry L. Cooper, an expert in ethics for law enforcement officers at the University of Southern California, told The Times. "That was done very well."
Lisa Graziano, an associate professor of criminal justice at Cal State Los Angeles, agreed. "The behavior of the officer came off as standard. From what I saw, he seemed to handle it very professionally."
Graziano and Michael Rains, a California attorney who represents officers accused of misconduct, focused on Slager's shouts of "Taser!" that can be heard on the dashboard camera audio.
Officers are trained to announce that they are about to use a Taser, which would indicate there was a struggle, Rains said.
"That is pretty clear evidence to me that ... the officer intended to use his Taser and did so ineffectively," Rains said.
According to police reports, after shooting Scott, Slager radioed the dispatcher: "Shots fired and the subject is down. He took my Taser."
The dashboard camera audio could support Slager's claim that the Taser was out, Graziano said, but doesn't necessarily back up his assertion that Scott reached for it. Nor does it prove that Scott was a threat to Slager or anyone else, she said.
Rains suggested the video could be used in Slager's defense, at least to indicate that he really tried to use the Taser.
"I don't think that when an officer is in the midst of chasing somebody and is trying to take them into custody, they’re fabricating a defense knowing that in five to 10 seconds they're going to shoot this person," Rains said.
Scott should have stayed in the car, all three experts agreed, but running away didn't give Slager license to shoot.
It's never OK to flee, Graziano said. "You never know what will happen in a police-citizen encounter. ... Many use-of-force cases are precipitated by the suspect resisting in some way or trying to flee."
Cooper agreed. "The worst thing you can do in any encounter with a police officer is challenge his authority and attempt to avoid arrest or a citation. ... But it certainly did not warrant shooting him."
Once Scott did flee, Rains said, it was standard for Slager to chase him.
"A police officer’s mind works like this: If a person doesn't want to get a ticket, why did they run away from a cop?" Rains said. "There’s something else going on here that he doesn't want me to know about. ... I'm going to find out why he's running from me."
But Cooper called the chase "a risky thing to do."
"He has no partner with him and he could find himself far from his car and in a risky situation. The best thing to do is simply stay in the car and call his dispatcher," Cooper said.
Once Scott has been shot, the bystander's video appears to show Slager dropping his Taser by the body.
Rains alluded to that. "I think the evidence shows that Officer Slager did go back and get the Taser and then took it over by the body."
The attorney said, "Clearly a Taser was involved, and the bystander said he heard the Taser going off. It still makes the shooting at this stage as far as I can tell indefensible. ... It doesn't justify under any legal theory being shot in the back."
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Times staff writer David Zucchino in North Charleston, S.C., contributed to this report.