Three years after Michael Brown was fatally shot by police in Ferguson, Missouri, the town’s former top cop wants to get a few things off his chest.

In his book, “Policing Ferguson, Policing America” (Skyhorse, out Tuesday), Thomas Jackson details the August 2014 shooting of the unarmed black teen by a white cop that launched a series of violent protests around the country for months as demonstrators and critics claimed the killing reeked of racial injustice and police brutality. A St. Louis County grand jury and the Justice Department would both later decline to prosecute Officer Darren Wilson, citing “multiple credible witnesses” who supported his claims that Brown, 18, had attacked the cop before being shot.

The shooting’s aftermath thrust Jackson into the hot seat, making him the “primary focus of a nation’s outrage” in its wake, he claims. And it was a few key decisions made during the initial hours after the shooting — including the “inflexible protocol” of leaving Brown’s body lying in the street for four hours — that he says created such a damaging narrative for police.

“Anybody who has watched a police drama on television knows that you don’t move a body at a crime scene until the forensics team has examined both the body and the scene in detail,” Jackson wrote. “Moving the body can cause lost or tainted evidence … On that Saturday, an ambulance had arrived right away. [Wilson] had been on an ambulance call just prior to the episode on Canfield [Drive], and the ambulance had been just minutes behind him. The EMTs determined that Brown was deceased. Since they were unable to do anything more until the crime scene team arrived, they left the scene.”

But the anti-police message spreading on social media, according to Jackson, was that he, “as the face of the Ferguson police,” had left Brown’s body in the street to deliberately intimidate residents in the town of 21,000.

“Supposedly, I wanted to send a message that this could be anyone who hadn’t behaved, that the Ferguson police were willing to gun people down in the middle of the street for no reason,” Jackson wrote. “When the investigators were finally able to remove Michael Brown’s body, they did so in the first available vehicle, a black coroner’s SUV. Again, the lack of ceremony was described online as an insult.”

And if Brown’s body had been moved before the scene was processed, Jackson claims it would’ve led to valid grounds for any claims of police misconduct.

“Damned if you do, damned if you don’t,” Jackson wrote. “I chose to play it by the book and ensure a proper accounting for what happened that day. I wish there had been another option.”

Jackson also second-guessed the use of police dogs to control the crowd of mostly black protesters, a decision made by a county police captain that “could not have looked worse” on that humid afternoon.

“It immediately conjured up memories of Selma and Little Rock and Bull Connor, and provided the first piece of ammunition for anyone who wanted to paint the police to be the dangerous aggressors, rather than peacekeepers we believed we were,” Jackson wrote.

In another passage, Jackson attempted to explain the department’s use of tear gas, claiming protesters were always given advance warnings to disperse before deployment. He discussed the tactic and how it fit into the larger narrative in a chapter focusing on optics, a term Jackson said he had never heard prior to the shooting outside an optometrist’s office.

“The narrative persisted despite the obvious facts on the ground,” Jackson wrote. “At the same time, tear gas exists in our collective unconscious as a weapon of oppression, conjuring up images of noble protesters and activists from the civil rights and Vietnam eras being manhandled by faceless, battle-ready police. So the mere mention of tear gas played into the assumed narrative.”

No one was more responsible for that narrative, Jackson said, than then-Attorney General Eric Holder, who arrived in Ferguson just 11 days after the shooting — giving “tacit confirmation of the public fear that wrong had been done” and that prejudice was a factor.

“He made the job of law enforcement even harder than it already was, putting the public and police both at greater risk,” Jackson wrote.

Jackson would later resign following a scathing Department of Justice report that found a “revenue-driven” police department and court system that disproportionately hurt African-Americans and violated constitutional rights in Ferguson. But, in Jackson’s mind, “too many Americans are still deeply invested” in the “hands up, don’t shoot mythology,” which was ultimately not supported by eyewitnesses, according to the DOJ’s separate report on the shooting itself.

One of the consequences of that disparity, Jackson claims, is to reflexively blame police for what he calls a “broken society,” especially as the national conversation about policing continues to evolve with every police-involved shooting.

“It’s become our primary job to undo all the effects of all these years of supposedly corrupt and oppressive policing,” Jackson wrote. “The nation seems to have collectively decided that everything about policing is f–king up, and while no one’s quite sure how to do it, the police have been assigned with getting it un-f–ked.”