They say confession is good for the soul.

If that is true, the likelihood is that former fighter Luis Resto finally has gained some measure of peace after coming clean as to the full extent of his participation in one of the ugliest scandals ever to have blighted the frequently soiled sport of professional boxing. Resto is the conflicted and ultimately redeemed subject of producer/director Eric Drath’s compelling HBO documentary,  Assault in the Ring, which debuts Aug. 1.

During a remarkable transformation in which he first portrays himself as an innocent dupe for his role in the criminal tampering of his gloves for a June 16, 1983, bout in Madison Square Garden that left “Irish” Billy Collins frightfully battered and perhaps suicidal (Collins died after a March 26, 1984, car crash that might or might not have been an accident), Resto gradually allows decades of layered guilt to be stripped away. Yes, he eventually reveals to Drath, he knew much of the horsehair padding from his gloves had been removed and that he was complicit in that he realized it was wrong but did not object. Yes, there was a banned stimulant in the water bottle he sipped from between rounds. Yes, his handwraps had been doctored with a plaster-like substance that made the power in the punches he delivered to Collins’ face with those thinly padded gloves even more devastating. And perhaps most damningly, all these actions were undertaken to serve the gambling interests of a cocaine trafficker who sought to make a bundle by placing a sizable wager on Resto, a journeyman gatekeeper of the welterweight division who had not been expected to provide much more than token resistance to rising star Collins.

Given the recent controversy that arose from the revelation that Antonio Margarito had attempted to enter the ring for his Jan. 24 bout with Shane Mosley with doctored handwraps, which led to Margarito and his trainer, Javier Capetillo, being socked with one-year suspensions from the California State Athletic Commission, Assault in the Ring serves as a cautionary tale that vigilance against the cheaters and rules-benders must be constant, and the penalties for such offenses must be swift and severe.

In baseball, the artificially inflated sluggers of the steroids era did their damage to inanimate objects, baseballs, which can’t feel pain regardless of how hard and far they’re swatted. But a fighter who goes answers an opening bell with the equivalent of bare knuckles – or, worse, brass knuckles – can not only end an opponent’s career, but maybe his life. He, in fact, has allowed himself to be transformed into an even more lethal weapon in a sport where, in the best of situations, danger is an occupational hazard.

But if Collins, who never fought again, is the principal victim, and Resto’s ruined and guilt-wracked life nebulously falls into the category of collateral damage, there has to be a villain, someone whose complete lack of conscience supplies that quality of evil that can veer an illegal action into full-blown tragedy.

Trainer Carlos “Panama” Lewis, like Resto, served 2½ years after convicted of multiple charges, including assault, conspiracy and tampering with a sports contest. But, unlike Resto, a smirking, bling-blinged Lewis continues to proclaim his innocence despite evidence that has mounted higher than the Empire State Building. The most repugnant aspect of Drath’s documentary is that Lewis, although barred for life from working the corner of a client-boxer on fight night, still is able to hire out as a conditioner and strategist to fighters on a day-to-day basis. Remarkably, there are those who, recalling Lewis’ past association with such renowned champions as Roberto Duran, Aaron Pryor, Vito Antuofermo, Mike McCallum and Livingstone Bramble, still choose to place their professional futures in his disgraced hands.

Panama Lewis reminds me of the husband who, upon being discovered by his wife in bed with a mistress, innocently asks, “What woman?” as she gathers up her clothes and bolts out a side door. When exposed, the first rule for dirtbags like Lewis apparently is to deny, deny, deny. Hey, if you claim to have been persecuted or misunderstood long enough, maybe someone in a position of authority will take mercy and grant you a license to make a full return to your old trade.

“Give somebody a chance to make a living,” the Miami-based Lewis said last year in an interview with Rochelle Gilken, a former amateur boxer who is now a reporter for the CBS affiliate in West Palm Beach, Fla., WPEC-TV. “So far, I don’t see that.

“I didn’t cheat. I used my head for motivation. I don’t have to cheat in boxing. Boxing is my life. I’m blessed with this. They can take away my license, but they can’t take away my knowledge.”

It isn’t only a suddenly contrite Resto who spills his guts and lays out the case against himself and Lewis to a wider extent than was revealed at their 1986 trials. A former New York City detective, who went undercover as a jogger running alongside Resto, wore a wire and got the fighter to confirm certain details of the plot against Collins. Procedural reasons caused that tape to be ruled inadmissible, probably paring some additional jail time from the sentences handed Resto and Lewis and keeping the door cracked open slightly to claims the plotters somehow had been framed.

Resto’s former attorney, Robert Beecher, confirms that a cocaine dealer had a vested interest in ensuring that Resto pull off the upset over the undefeated Collins. Thomas Moore, a former New York assistant district attorney, is quoted on camera that when the drug kingpin wanted assurances that his wager would be safe, Lewis said, `Don’t worry about it, I’ll take care of the gloves.’”

No wonder Resto, the Puerto Rican-born son of a single mother who came to the Bronx when he and his five siblings were kids, seems so emotionally fragile during the early part of the documentary, when he continues to insist that he didn’t really know what was going on or who had done what.

Even Drath admits that his intention going into the project was to affirm Resto’s innocence, to expose the truly culpable while providing Resto, who said he is haunted daily by visions of Collins’ brutalized face, the sense of closure that would enable him to go on without the burden of constant recriminations.

But revisiting estranged members of his own family and relatives of Collins, some of whom are willing to forgive if not forget, and others that can never let go of the past, had a cathartic effect of Resto. If he was to ever free himself of the self-loathing that hovers above him like a restless ghost, he had to finally purge himself of the lies he had been telling himself and the world for so long.

Perhaps the closest thing to a feel-good moment in a tale that does not allow much room for hope comes toward the end when a tearful Resto confesses to Collins’ widow, Andrea Collins-Morse, that everything she previously had believed of him, and worse, was true. Collins-More hugs him, says she knows how difficult it must have been for him to finally admit what he did, and she says she thinks he is a good man.

Less conciliatory is Billy Collins Sr., who refused to open the door of his modest Nashville, Tenn., home when Resto knocked on it to request a face-to-face meeting during which he would apologize for the wrong he had done.

Then there is Panama Lewis, who was not flummoxed in the least when confronted by the former fighter and the filmmaker who mistakenly believe that such an encounter will lead him to also confess his misdeeds. But Lewis is a master of turning any situation to his advantage, and he greeted Resto in a manner that suggested that he remains the actual wronged party. He quickly badgered Resto into thinking he was still “like a son” to Lewis.

“Trust me,” Lewis said. “I do good, you be in. Stay strong, Resto, you gonna be all right. It’s in the hands of God, you understand? God looks over everybody.”

Continuing to drag the Almighty into the discussion, Lewis responded to a question as to the extent of his knowledge regarding the tampered gloves with “Only God knows. Until this day, nobody knows what happened with the gloves. Hopefully, one day, the truth will come out.”

Later, during a trip to New York where one of his fighters, Zab Judah, was to face Miguel Cotto, Lewis – barred from working the corner – stayed away from the Garden and watched the bout on television in a tavern across the Hudson River, where he sneeringly described to the barkeep, an old friend, how a crying Resto had shown up in Miami seeking his approval.

Maybe Resto, if he was shown footage of the contempt in which Lewis actually held him, was sufficiently emboldened to return to Miami and to finally accuse him of the serial offenses that have made Lewis a boxing pariah. When Resto informed his former trainer that he knew what was going on when Lewis went into a toilet stall with the gloves, Lewis said, “I went to take a piss!” Sure, everyone brings boxing gloves to the rest room when they feel the urge to urinate.

And Resto’s contention that it was Lewis who wrapped his hands with that plaster-like substance?

“I did not wrap your hands! (Assistant trainer) Artie Curley wrapped your hands!” Lewis yells, a response that is most convenient in that Curley died years ago.

You have to wonder, though, what Top Rank founder Bob Arum has to say about a documentary that seemingly indicates that he has no set position on what does or does not constitute wrongdoing in the ring, or at least the appearance of wrongdoing. Arum promoted Collins on that fateful night 26 years ago, and he describes him as “a great-looking kid” who had “all the moves,” “could punch like a mule” and potentially was a box-office “gold mine.”

Of Lewis – or maybe it was Resto, Arum’s response on the matter is a bit vague – he said, “What he did was inexcusable. He should be banned from the sport forever. There shouldn’t be any forgiveness.”

A refusal to give perpetrators of the Collins tragedy any benefit of the doubt seemingly is in contrast with the slack Arum is willing to cut Margarito, although he was less inclined to give a pass to Capetillo, the most convenient of the possible fall guys. But then nobody pays big bucks to see Capetillo wrap hands or dispense advice in the corner, and Margarito is – or at least was – an important member of the Top Rank promotional stable.

The upshot, of course, is that there are cheats who were and still are in the game and their only chance of being brought to justice is if they’re caught in the act by state commissioners who too often are political appointees incapable of recognizing illegal handwraps or unpadded gloves even if they came with flashing neon lights. The need for strict regulation of boxing is as important now as was in 1983 or at any time in the past.

If there is a positive that can come from what happened to Billy Collins, it is that his beatdown and death do not have to be in vain. All of us who love boxing must demand greater accountability of our officials to better ensure that detectives and prosecutors won’t have to be called upon to obtain justice after the fact.