U.S. Attorney Jim Letten has demoted his first assistant U.S. attorney, Jan Mann for posting comments on NOLA.com. 

Letten has also removed Mann as chief of the criminal division of his office.

The allegation was first raised in a civil lawsuit filed by Jefferson Parish landfill owner, Fred Heebe.  Heebe, who is being investigated by federal agencies, charged that he had been defamed by Mann in anonymous online posts.

Earlier this year Heebe identified a former top official in Letten's office, Sal Perricone, as the author of hundreds of comments posted on NOLA.com.  Perricone, who was the senior litigation counsel for the office, resigned and retired after his actions came to light.

Letten took the action in Mann's case on Monday night after he apparently confirmed the accusation made by Heebe. He says that since the department is now reviewing the matter, he cannot comment further.

There's speculation the latest revelation could jeopardize Letten's future as the U.S. Attorney for the Eastern District of Louisiana. 

In an email on Thursday morning, Letten said he immediately contacted the appropriate officials with the Justice Department in Washington when he learned of the allegations contained in the suit.  "In accordance with well-established protocol, the Department of Justice Office of Professional Responsibility was notified."