ATLANTA >> When Gwinnett County officer Robert McDonald ran onto the scene and immediately stomped on a handcuffed motorist’s head to get him under control, it probably seemed natural to him.

The relatively new cop — in a widely viewed video — had been learning from the master, Sgt. Michael F. Bongiovanni, a burly veteran officer who was a cop’s cop, a one-man wrecking crew adept at meting out justice when it came to those he saw as criminals.

Over an 18-year career at Gwinnett, Bongiovanni had 67 use-of-force incidents, almost four a year, although his numbers dropped in the past decade since becoming a supervisor. In his first three years on the department, Bongiovanni had to get rough with suspects or motorists 19 times.

After he gained stripes, he still liked to keep his hand in the game. He had 23 use-of-force incidents since making sergeant in 2007. He was a “lead by example” guy, a trait often mentioned in his annual evaluations. That was an attribute that drew younger officers like McDonald to want to emulate him.

It is also fitting to note that none of Bongiovanni’s use-of-force incidents — whether they be hands, knees, spray, Taser or metal baton — ever brought a sanction until his last one, which was caught on a cellphone video.

It was an act that got him drummed out of the department. Or at least, for now. It’s a well-known fact that rough cops are often able to quietly slide off into other departments.

As I noted, even Bongiovanni’s 67th use of force was initially ruled kosher until video surfaced of him punching Demetrius Hollins in the face Wednesday afternoon after a traffic stop. Hollins, who was pulled over for not using his turn signal, apparently became argumentative.

I say “apparently” because Bongiovanni was caught not being truthful in his report on the incident. He said nothing about clocking the dude in the face. So one might wonder how many omissions and obfuscations occurred in his 66 other cases.

In fact, the Gwinnett solicitor’s office on Friday dropped 89 traffic and misdemeanor cases having to do with McDonald and Bongiovanni because of such worries about the truth. District Attorney Danny Porter said he will review his cases. He also is weighing possible charges such as battery, assault under the color of law, violation of oath of office and making false statements, the latter two being felonies.

“It’s very stunning,” Porter said. “(Bongiovanni) has always been the cop on the front lines; he’s been down in the ditch. He’s been a good officer who made a mistake, if it was that.”

Incidentally, at the end of his shift Wednesday, Bongiovanni reported his underling’s stomping of the same skinny guy he knocked silly.

“Maybe he just sees the wrong in others,” Porter said.

Now, don’t misunderstand me, lots of people could use a beating. But cops in a civil society must get smarter and more lawful when it comes to dealing with with the public, even miscreants — especially since there seems to be a cellphone camera at every interaction.

In the case at hand, Bongiovanni already knew Hollins, having stopped him last year with weed and a gun in his car. Both times, Bongiovanni said, Hollins was acting squirrely and argumentative. Just looking at Bongiovanni’s physical stature and no-nonsense record, it would seem he’s not a person you’d debate on the side of a highway. But that’s what seemingly happened, and the encounter rolled out of control.

The incident first came to light when a motorist filmed Bongiovanni struggling with Hollins and handcuffing him face-down on the pavement next to his car. McDonald then bolted into the picture as the sergeant stood up to catch his breath and stomped the young man’s head.

The disturbing vision was widely distributed on the internet, causing Gwinnett County Police Chief Butch Ayers to quickly fire McDonald and hold a news conference.

Obviously, the chief did not want to be like the United Airlines CEO, who equivocated as video of a passenger being dragged off a plane went worldwide.

“The suspect was lying down, he was clearly handcuffed, he was clearly not resisting,” the chief said at a news conference Thursday. The chief also commended Bongiovanni for how he handled the incident and for reporting McDonald to his shift commander.

About the same time, a second video — shot by a second person — was gaining traction on the internet. Next thing you know, Chief Ayers is holding another press conference that night and Bongiovanni is a former policeman.

“We acknowledge that the actions of these two officers have implications that will be felt for some time,” Ayers said.

Internal police records — which were quickly released by the department — show Bongiovanni as gung-ho a cop as you can be. As a gang-crimes officer, he was praised for initiative, work ethic and knowing Spanish, which made him a sought-after translator by comrades.

He was funny and fearless, twice rescuing people out of bad car wrecks, one of them while the vehicle was burning. In one rescue, he hurt his back, leading to surgery. He and his units routinely were among the department’s tops in arrests. He has been commended for nabbing carjackers, kidnappers, killers and all sorts of street-level pests.

As a supervisor, he was equally commended.

“His style of leadership is leading by example,” a supervisor noted in 2008.

“He does not ask subordinates to do anything he wouldn’t do himself,” another noted a year later.

But I still wonder about the 67 use-of-force incidents that went unchallenged all these years until a video popped up.

In a police accounting sheet of the incidents, a box is checked on whether the use of force was “effective” or not.

Wednesday’s was checked as “effective.”

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