Judge Kurt Engelhardt’s decision overturning the convictions of five New Orleans police officers for their roles in the Danziger Bridge shootings runs to 129 pages. Page by page, the decision addresses claims of prosecutorial misconduct, and it is as if, page by page, the judge’s anger and disbelief only grow.

He finds ample misconduct, and terms it “grotesque.” He uncovers other damning material, and professes “shock and dismay.” In the end, he closes with a distinct sense of foreboding: The worst may be yet to come.

“One can only wonder what other unanticipated revelations might be in store,” he writes.

Engelhardt’s central finding was that federal prosecutors, during the trial of the officers for the shooting of unarmed civilians days after Hurricane Katrina, had posted anonymous comments on the website of the local newspaper, the Times Picayune.

Here’s how Engelhardt characterized those comments: “inflammatory invectives,” “accusatory screeds,” “vitriolic condemnations,” all of them directed at “the defendants, their attorneys, their witnesses, their evidence.”

Engelhardt said that the online misconduct – prosecutors in New Orleans and at the Department of Justice in Washington posted comments themselves and encouraged other anonymous people to post, as well – created a “carnival” atmosphere, “wherein justice was distorted and perverted.”

ProPublica has spent much of the last year investigating prosecutorial misconduct, how the innocent can be convicted and how infrequently the offending prosecutors get punished. Much of the misconduct has been committed by state prosecutors, and the assumption among many is that federal prosecutors are more sophisticated and better trained, and thus less susceptible to bad or illegal behavior.

But the remarkable passages across Engelhardt’s decision do serious damage to that assumption.

• The senior federal prosecutor Engelhardt assigned to independently investigate the possibility that attorneys in the New Orleans office were posting comments online wound up having to admit that she, in fact, was among the guilty.
• The prosecutor in Washington who posted online during the trial was, it turned out, the woman who had led the prosecution’s “taint team,” a group of attorneys whose job was to protect the constitutional rights of the accused officers.
• The Justice Department’s Office of Professional Responsibility, charged in 2012 with investigating the initial report of online posting by a senior prosecutor in New Orleans, failed in its initial investigation to ask whether any other prosecutors in the office had done similarly.
• Engelhardt, in the course of his inquiry, came to suspect that reports being filed by the outside prosecutor he’d enlisted in the name of objectivity were being edited by senior officials at the Justice Department to make them less damning.

“Some may consider the undersigned’s view of the cited rules and regulations as atavistic,” Engelhardt writes at one point. “But courts can ignore this online ‘secret’ social media misconduct at their own peril. Indeed the time may soon come when, some day, some court may overlook, minimize, accept, or deem such prosecutorial misconduct harmless ‘fun.’” Today is not that day.”

The Justice Department responded to Engelhardt’s ruling by saying it was disappointed and reviewing its options. Neither the department nor the individual prosecutors cited by Engelhardt have publicly responded to his specific findings of misconduct.

Engelhardt’s ruling certainly amounted to a huge embarrassment for federal prosecutors. The prosecution of the officers had been hailed as a civil rights triumph. When the indictments were announced in 2010, the Justice Department said they were “a reminder that the Constitution and the rule of law do not take a holiday – even after a hurricane.”

Now, prosecutors will have to decide whether to re-try the officers. Four had been charged in the killing of two civilians and the injuring of others, and the fifth was charged with attempting to cover up the incident. Engelhardt, in his decision, recognized that the prospect of a re-trial, for the victim families and the officers, would be painful. But he found there was no acceptable alternative.

“This case started as one featuring allegations of brazen abuse of authority, violation of the law, and corruption of the criminal justice system,” Engelhardt wrote. “Unfortunately, though the focus has switched from the accused to the accusors, it has continued to be about those very issues. After much reflection, the court cannot journey as far as it has in this case only to ironically accept grotesque prosecutorial misconduct in the end.”

Engelhardt began his inquiry into the case he had overseen when the officers asked him to toss the verdicts. The officers cited reports that one senior prosecutor in New Orleans had posted online before and during the trial, ultimately calling for guilty verdicts against all five. It would take more than a year for Engelhardt to get the answers to what, for him, became a growing list of questions.

“The court has continued to receive more and more information,” he writes early in his decision, “albeit in the fashion of peeling layers of an onion.”

Over the months, the U.S. Attorney in New Orleans resigned because of the online misconduct of his office. Soon after, the senior prosecutor Engelhardt had asked to help him get to the bottom of the matter in the Danziger case, Jan Mann, resigned as well. She had posted online, too, even though she never told that to the judge when he enlisted her help.

Eventually, Engelhardt got two prosecutors from Georgia to take over the Danziger misconduct inquiry. But they had to file four separate reports before Engelhardt was satisfied he was being told something like the full truth. Along the way, he challenged them to reassure him their reports were not being sanitized by superiors. The prosecutors insisted, orally and in written responses, that they had maintained editorial control throughout.

In his decision, Engelhardt tried to capture the escalating trouble he was learning of, saying his first findings had “clearly blossomed into a series of newly discovered facts and admissions, unanswered questions, additional apostasies, and a fetor extending far beyond the simple disconcerting notion of a single rogue prosecutor.”

Engelhardt, upset by the online misconduct, was then moved to think again about some things that had troubled him at trial. In his decision, he blasts prosecutors for having threatened possible defense witnesses, notes that the testimony of one prosecution witness differed dramatically from what he had told federal investigators, and wonders why another prosecution witness had worked for the federal government despite having admitted to a series of crimes.

In tones of exasperation and sarcasm, Engelhardt writes that he found it “odd” that it took months for him to be told that one of the prosecutors involved in the online posting was the Washington attorney who had effectively represented the interests of the officers in the case. He later writes that he finds its almost unthinkable that she did what she did – write posts encouraging anonymous commenters on the case to keep up their criticism of the defense being put forward by the officers.

“It is difficult to accept the story that an experienced trial attorney in the criminal section of the DOJ’s civil rights division, sitting in Washington, D.C., during this trial, 'would embark on such a wanton reckless course of action.'” The attorney, Karla Dobinski, formally admits to the postings during Engelhardt’s inquiry, conceding it was wrong and that she had as a result sought to conceal her true identity.

It is unclear whether the prosecutors involved might face some sort of sanction. Engelhardt, for his part, says that question is up to others.

“The court leaves to the various bar associations and other attorney regulatory bodies the question of who knew what, when they knew it, and whether they discharged ethical and professional responsibilities to report/disclose it.”

But Engelhardt is clear in his decision about what he asserts is the damage already done, saying his investigation had led “to a dark benthic place of prosecutorial misconduct.”

The myriad acts of misconduct, he writes, were “committed by those with significant authority who act in the name of the ‘United States of America’ when they enter court and at all other times, and who have now left a fractured public trust.”