One of the most ambitious federal cases in local memory ended with a whimper Wednesday when the last remaining defendant — who admitted taking nearly a half-million dollars in bribes — was sentenced to six months of home confinement and three years of probation.

A visibly frustrated U.S. District Judge Martin Feldman imposed the lenient sentence on Henry Mouton after railing about the misconduct of prosecutors in the case and the government’s subsequent refusal to turn over a report investigating that misconduct.

“I don’t think anyone would dispute the rather odd and unusual circumstances of this case,” Feldman said, calling a conspiracy with only one charged conspirator “pretty metaphysical.”

“I think any rational person should be concerned about the possibility of, in this case, stories of prosecutorial misconduct and government abuse at even higher levels, which troubles me greatly, which leaves Mr. Mouton here to be the only person sentenced after an investigation of this nature has been dropped,” Feldman said.

Ultimately, Feldman pronounced himself disgusted with Mouton’s conduct, but said a light sentence was in order both because of Mouton’s low risk of recidivism and because of the judge’s unease with the government’s conduct in the case.

More than two years ago, Mouton, 56, admitted taking $463,000 in bribes from the owners of the River Birch landfill in exchange for using his seat on the state Wildlife and Fisheries Commission to cast aspersions on the Old Gentilly landfill, a rival operation to River Birch that opened amid the debris gold rush that followed Hurricane Katrina. Though he had little if any influence over landfill policy, Mouton — a hunting buddy of former Gov. Mike Foster — sent letters on commission letterhead to various people in power, denouncing Old Gentilly and another would-be River Birch rival.

It appeared that Mouton was auditioning for the role of star government witness in the case the FBI was building against River Birch’s owners, and local political heavyweights Fred Heebe and Jim Ward, the probe’s ultimate targets. The theory of the case appeared to be that Heebe and Ward had built a near-monopoly on the trash business in southeastern Louisiana, in part by donating lavishly to politicians, sometimes through straw companies.

But the wealthy Heebe signed up a high-powered, aggressive legal team and went on the offensive, training his sights on an office accustomed to keeping defendants on their heels. In March 2012, he filed a civil suit that exposed federal prosecutor Sal Perricone as the author of hundreds of pseudonymous rants under stories posted at nola.com, many of them involving federal targets, among them Heebe. Perricone quickly resigned, and then-U.S. Attorney Jim Letten asked the Justice Department’s Office of Professional Responsibility to probe the matter.

The wreckage didn’t end there. Eight months later, Heebe struck again, this time alleging that Jan Mann, Letten’s longtime first assistant, had also authored online rants at nola.com. Again, his aim was true. In short order, Letten, Mann, and Mann’s husband, Jim Mann, another top prosecutor in the office, were all gone, and Dana Boente, a federal prosecutor from Virginia, was named to oversee the office on an interim basis. Letten’s office recused itself from the landfill case, which was taken over by Washington, D.C.-based prosecutors from the Justice Department’s Public Integrity Section.

Meanwhile, U.S. District Judge Kurt Engelhardt, who was overseeing the massive Danziger Bridge police shooting case, issued a stinging order in which he accused both Jan Mann and Perricone of being dishonest. He also pointedly questioned whether the Justice Department was devoting sufficient attention to ferreting out the problems in the office. Another prosecutor, John Horn, of Atlanta, was soon brought in to investigate the office more fully.

Three months later came a new bombshell: The Justice Department announced it was ending the landfill probe without any new charges. Heebe and Ward were in the clear, as was Dominick Fazzio, the River Birch chief financial officer whom the feds had charged in an unrelated scheme to loot money from a construction company.

Others caught up in the dragnet weren’t as lucky. Fazzio’s brother-in-law, Mark Titus, had already pleaded guilty in the construction scheme, and Hank Ton, owner of an oilfield services firm, had pleaded guilty to tax charges in a case that also implicated Fazzio. The charges against Titus, Ton and Mouton all stuck, even though the probe’s ultimate targets were in the clear.

Only Titus has had to go to prison; he is serving a five-year term. Ton, who was represented by Kenneth Polite, who is expected to replace Boente as U.S. attorney in the next few weeks, received probation.

It’s not clear what, if anything, has come from the probes overseen by Horn and by the Office of Professional Responsibility, or whether they are still ongoing. The Justice Department has declined to provide either report in response to Freedom of Information Act requests.

Feldman said he wanted the federal probation office to have access to the Horn report for use in preparing a sentencing recommendation for Mouton, but that the Justice Department was apparently unwilling to provide it.

“Why would you not just turn over the papers?” Feldman demanded of prosecutor Brian Lichter, who, as the lone representative of the Justice Department at the hearing, took on the role of whipping boy at several points.

“Your Honor, quite frankly, I don’t know why that decision was made,” Lichter responded.

Feldman asked both sides what they thought an appropriate sentence for Mouton would be. Lichter said the government thought Mouton should get credit for cooperating with investigators, even though his help didn’t lead to further indictments — a fact Lichter acknowledged was at least partly outside of Mouton’s control.

Lichter told Feldman he thought a four-year prison sentence, rather than the five years recommended by federal guidelines, would be appropriate.

Mouton’s lawyers, Mary Olive Pierson and E.J. Hurst, asked that Mouton be spared any prison time.

Feldman initially seemed skeptical.

“I think people in this state and in this community are pretty much sick and tired of public corruption wherever it occurs,” he said. Later, he added, “I think that we might be a war-weary country, but I think we are more weary about what we observe here in our own communities and our own culture. ... If people have no faith in our elected leaders, if they have no faith in people who work in communities, it’s because of people like you who have disgracefully dishonored the name of public service and the notion of serving one’s community.”

When Hurst acknowledged that Mouton’s conduct “does look terrible on paper,” Feldman cut him off, saying: “It’s not just on paper. It’s terrible. It’s not just on paper. He says he did it.”

But in the end, the judge took mercy on Mouton, and meted out a sentence of six months of home confinement, three years of probation and a $100,000 fine. He made it clear to the courtroom how nettlesome he found the case.

“This court has been given no just or fair reason by the Department of Justice why Henry Mouton has been pursued although the government’s general investigation has been acknowledged to have been abandoned and not disputed by the government of the United States,” Feldman said. “The court is deeply troubled by what to any reasonable person might be potential unyielding government abuse.”