Whether one believes that Ronnie Coogle had a change of heart when his word was used to justify the killing of a guy who smoked some pot, it’s hard to come up with any other rational explanation for why a guy who always put his self-interest first would now risk his life. There just wasn’t any benefit in it. Yet he did.

A 50-year-old felon and drug addict, Coogle was the principal Tampa Police Department informer against at least five suspects this year. He conducted nine undercover operations. In their probable-cause affidavits, his handlers called him reliable. Even Tampa’s police chief praised his “track record.”

Coogle said they were all wrong. He said he repeatedly lied about suspects, stole drugs he bought on the public’s dime and conspired to falsify drug deals.

But as long as he was playing on the cops’ team, he was as solid as they come. Solid enough to send out the SWAT team after Jason Westcott.

One of those he lied about, he said, was Jason Westcott, a young man with no criminal convictions whom a SWAT team killed during a drug raid that found just $2 worth of marijuana. Critics from across the country condemned the Police Department’s handling of the case as an example of the drug war’s lethal excesses.

“They’re making statements that are lies, that are absolute untruths, that are based on shady facts,” Coogle said of Tampa police. “Everything they’re saying is based on the informant. And I was the informant.”

This was too much for Coogle, who came forward to the Tampa Bay Times’ Peter Jamison to spill his guts.  Miraculously, Coogle was no longer loved and trusted by the cops.

Coogle is nobody’s idea of a righteous whistle-blower. The only constant in his story is his own dishonesty; even when he confesses to lying you don’t know if he’s telling the truth.

Much of what he says can be neither proved nor disproved, in large part because of the Police Department’s minimal supervision of his work. But Coogle’s allegations against the cops who paid him, and even his own admissions of double-dealing, aren’t necessarily what’s most disturbing about his account.

Most unsettling of all might be what nobody disputes — that police officers were willing to trust somebody like him in the first place.

Meet your snitch, judges.  Meet the guy whose “information” you rely upon when endorsing the next move, the no-knock entry with automatic guns drawn and flashbang grenades.  Upon his word, people die.

Coogle has flagrant credibility problems. His rap sheet is a minor monument to criminal stamina: As a teenager he went to prison for robbery, and since then he has been arrested for beating a man with a baseball bat and threatening to cut his wife’s throat, among other things.

He began working for the Tampa Police Department shortly after spending eight months in the Hernando County Jail for pulling a knife on a woman who had given him a ride to a Brooksville Winn-Dixie. The victim in the case, Sarah Tousignant, summarized her impression of Coogle in an interview with the Times: “Mentally unstable, psychotic, crazy.”

But for a few bucks, the Tampa police were more than happy to have Coogle on their team.

“He’s just the scum of the f—— earth. I hate to say that. I hate to cuss. But it’s the truth,” said his brother, Mike Coogle. “He is nobody to give information about nothing to nobody, because everything that comes out of his mouth is a lie.”

Coogle’s dishonesty raises obvious questions about his story, but it is also at his story’s heart. It was his willingness to lie, he said, that let him thrive as a drug informer for Tampa police.

And really, isn’t that exactly what the cops were buying?  A guy willing to say whatever the cops needed him to say, to be the warm body in the warrant application that allowed the cops to go after whoever they decided to go after?

In the hands of whoever prepared the warrant application, Coogle’s believability was one step shy of the Pope.  What judge could doubt his honesty, his integrity, when the police vouched for him.  And who could doubt the cops’ honesty, their integrity, when Coogle decided to switch teams after Wescott’s death?

After Coogle went to the FBI…[Chief Jane] Castor took a different view of the man whose truthfulness she had endorsed. “I don’t believe him at all,” she said.

In an interview with the Times several weeks after Coogle met with federal investigators, Castor and her chief spokeswoman, [Laura] McElroy, savaged the credibility of their one-time “reliable informant.” But only to a point.

They said they still believed the information he had fed to narcotics detectives about Westcott. They said it was only his recantation and accusations against his handlers that were untrue.

“You really think that this guy is in a position to question the integrity of police officers?” McElroy said. “A C.I.? Really? I mean, come on, C.I.’s are not upstanding citizens. It’s a joke.”

It is most assuredly a joke. It’s all a joke, except for the dead body of Wescott, which isn’t very funny at all.  Maybe irony is a better description, as no cop will ever write in a warrant application that anything a “C.I.” says is a joke, inherently unbelievable, because they are the scum of the earth.

And still, Chief Castor played both sides of the fence, bizarrely claiming that Coogle was credible whenever he was being paid by her cops for information, but an utterly despicable liar when he snitched on her cops.  But then, this is the side of snitches that isn’t supposed to see the light of day.

“It’s very unusual for the public to get a glimpse of how active informants interact with their police handlers,” said Alexandra Natapoff, a professor at Loyola Law School in Los Angeles who monitors informer use nationwide. “The criminal system is designed to make sure we never hear these stories.”

Now you’ve met Ronnie Coogle.  No doubt all the other snitches are fine, upstanding, trustworthy guys.