A New Orleans-based FBI agent filed a federal lawsuit Monday claiming the bureau violated his First Amendment rights last year when it suspended him without pay for sending an unusual letter to the judge who presided over criminal proceedings involving former St. Charles Parish District Attorney Harry Morel.

The agent, Michael S. Zummer, accused the FBI of retaliating against him for sending a 31-page letter to U.S. District Judge Kurt Engelhardt that criticized the way federal prosecutors handled allegations that Morel demanded sexual favors from women who were caught up in the criminal justice system.

Zummer, who served as lead agent in the Morel case, outlined a host of what he considered improprieties in his letter, claiming Morel received favorable treatment and that his plea agreement had been tainted by prosecutorial misconduct within the local U.S. Attorney's Office.

The agent disregarded bureau directives by sending the document to the judge on the eve of Morel's sentencing.

In a written order at one point, Engelhardt said he shared Zummer's concerns about whether the Justice Department "is either unable or unwilling to self-police lapses of ethics, professionalism and truthfulness in its ranks."

The judge declined to make the letter public, but Zummer ultimately released portions of it after the FBI, following a lengthy review, blacked out entire pages of the document, in which Zummer apparently implicated a list of government officials he said acted improperly in the Morel case. 

Federal authorities publicly accused Morel of being a "sexual predator" and of committing a host of crimes, including sexual assault, dating back decades, but they never pursued charges on those offenses.

Morel ultimately faced just one count of obstruction of justice, a charge that stemmed from his efforts to derail a long-running FBI investigation. The former district attorney is serving a three-year prison term.   

The new lawsuit, filed in U.S. District Court, asserts that Zummer's decision to send the letter to Engelhardt was protected by his right to freedom of speech. It offers new details about his suspension and says Zummer initially took pains to send the letter in accordance with FBI protocol.

Before being stripped of his security clearance and escorted out of the bureau's New Orleans field office, Zummer first was suspended from conducting any investigative activity and told that he "was to move his desk to the empty nurse's office on the second floor" of the FBI's lakefront office, the lawsuit says.

He received an email from a supervisor saying his new role was "not a punishment," but adding that he could not be assigned to cases anymore "because you have taken the position that information you personally gather in the performance of your duties as an FBI special agent may be disclosed by you as a private citizen ... despite being instructed not to do so without authorization." 

An FBI spokesman declined to comment on the lawsuit. 

A former Marine and a Stanford-educated attorney, Zummer has been prohibited by Justice Department rules from practicing law for compensation during his indefinite suspension and has been told he can take another job only with the FBI's permission, the lawsuit says.

In the suit, Zummer is asking the court for his old job back at the bureau, as well as back pay, damages and an order allowing him to make public the full letter he sent to Engelhardt about the Morel case.

Zummer wrote in the letter that he had encountered "systemic corruption" within the Justice Department and that he came under pressure at times to cover up the misconduct of federal prosecutors. 

The Morel case is apparently being investigated by the U.S. Justice Department's Office of Inspector General. It also has drawn the attention of the U.S. Senate Judiciary Committee, an influential panel of lawmakers that opened an inquiry into the case late last year. 

Follow Jim Mustian on Twitter, @JimMustian.