NEW ORLEANS — A south Louisiana landfill owner who is under investigation by federal authorities charges in a lawsuit that a second federal prosecutor defamed him in anonymous online posts.

Fred Heebe of New Orleans made the allegation against Assistant U.S. Attorney Jan Maselli Mann in a lawsuit filed Friday in state court.

Sal Perricone, another assistant federal prosecutor accused of similar behavior by Heebe, resigned in March after acknowledging he used the name “Henry L. Mencken1951” to post anonymously on Nola.com, the companion website of The Times-Picayune newspaper. The posts included critical comments about judges, politicians and cases.

Heebe’s lawsuit accuses Mann of posting under the name “eweman.” It says both “Mencken” and “eweman” displayed an interest in the U.S. Attorney’s Office’s investigation into River Birch Inc., a landfill co-owned by Heebe.

“And, like certain of ‘Mencken’s comments, at least two of ‘eweman’s’ comments about Mr. Heebe were libelous and defamatory,” the suit says.

Neither U.S. Attorney Jim Letten nor Mann responded immediately to a telephone request for comment.

Letten removed his office from a federal investigation of Heebe’s landfill in April after Perricone admitted to his online postings.

Heebe’s lawsuit bases the accusation that Mann is “eweman” in part on a repeated typographical error, “superfluous spacing before punctuation marks,” that it says is common in Mann’s writings. Also: “One post contains an obscure slang term — ‘fender lizard’ — that Ms. Mann is known to use in conversation,” the lawsuit states.

The suit also says “eweman” and Mann shared a mutual disdain for former U.S. Attorney Eddie Jordan and criminal defense attorney Arthur “Buddy” Lemann III.

“Significantly,” the suit adds, “all activity on the ‘eweman’ account ceased abruptly after the unmasking of Perricone.”

The lawsuit cites numerous postings by “eweman” and specifies two that it alleges were libelous or defamatory.

In one instance, a posting referenced a case in which a restaurateur allegedly promised to do business with a parish judge’s seafood company in exchange for favorable rulings in a child custody case. The posting said Heebe and the restaurateur were “birds of a feather,” which the lawsuit said is a false implication that Heebe has paid bribes.

“Eweman” also wrongfully accused Heebe of paying a local radio personality for favorable on-air comments, the lawsuit said.

Heebe has not been charged with a crime, but River Birch CFO Dominick Fazzio is charged with plotting to defraud a construction management company.

Also, a former state wildlife official pleaded guilty last year to charges he took more than $463,000 in payoffs from a landfill company owner’s businesses as a reward for work in trying to keep a rival landfill closed. The landfill company owner is identified only as “co-conspirator ‘A’” in the indictment against former state Wildlife and Fisheries Commissioner Henry Mouton, but the document says Mouton touted River Birch.

Revelations of Perricone’s online postings marked one of the few embarrassments for Letten, whose record of successful prosecutions of corrupt public officials — from local city and school system officials to former Gov. Edwin Edwards — have made him a popular figure in south Louisiana. In what is usually a patronage position, Letten has remained as U.S. Attorney under Republican and Democratic administrations, winning support from members of both parties.