A former maritime industry worker from Gretna was convicted in federal court Tuesday of 30 counts of mail fraud for the barrage of letters he sent demanding millions of dollars from co-workers, police officers, municipal employees and a state district judge, in some instances simply for speaking his name without his permission.

Melvin Lewis II, a so-called “sovereign citizen” who believes the government has no legal jurisdiction over individuals, also filed for liens on the property of some of his victims in an effort to extract payments, which he said escalated the longer they went unpaid.

Lewis, 53, was convicted after a one-day bench trial before U.S. District Judge Carl Barbier. He could get up to 20 years in prison and up to a $250,000 fine for each count when he is sentenced Oct. 13.

Lewis’ rampage began in 2013 after a promotion he said he was promised at Dynamic Industries Inc. didn’t materialize.

He responded by sending “demand for payment” letters to the company’s chief financial officer, a shift scheduler, the human resources manager and its attorney.

He went on a similar jag over a speeding ticket he got in Westwego that ensnared a police officer and two city officials.

Lewis’ letters typically had long official-sounding titles and were notarized and appeared to be sent by a third party, but authorities said they essentially amounted to extortion.

A letter to a co-worker, for example, was a “certificate of service” demanding the man prove he hadn’t misled Lewis about the promotion or else pay Lewis $376,000 — a payment that would roughly double every 10 days.

In Westwego, he claimed the speeding ticket was a charge not against him but against his car.

In other instances, Lewis would demand compensation from people who said his name without his consent. That was the case with 24th Judicial District Court Judge Stephen Grefer, who was informed via certified mail that he had 10 days to pay Lewis $102.8 million for violating Lewis’ personal copyright by using his name in court without his permission.

Sovereign citizens sometimes renounce their U.S. citizenship and claim to copyright their names, which they say prevents others from being able to speak or write them.

Ultimately, Lewis filed for millions of dollars in liens on the property of six of his eight victims.

He was arrested in April 2014 by the FBI’s New Orleans Joint Terrorism Task Force and Special Weapons and Tactics Team.

Follow Chad Calder on Twitter, @Chad_Calder.