Federal investigators are probing an arrangement through which a firm owned by Jefferson Parish Sheriff Newell Normand and his top lieutenant earns tens of thousands of dollars each year from the sale of food and other items by an offshore supplier to Harvey Gulf International Marine, a large oilfield-transport company run by politically active businessman Shane Guidry, according to sources with knowledge of the investigation.

On his most recent state financial disclosure form, from 2015, Normand reported earnings of between $25,000 and $100,000 from the firm -- called CTNN Enterprise LLC, apparently an amalgamation of his initials and those of his chief deputy, Craig Taffaro.

Normand has reported similar earnings every year starting in 2008.

The sources said authorities appear to be trying to determine what work Normand and Taffaro perform in connection with the arrangement, and whether any of the people paying them has received any official favors in return.

Normand was elected sheriff in November 2007; the job now pays him $176,000 per year.

He and Taffaro formed CTNN roughly a year later, according to state records. Normand’s disclosure records indicate the company is split 50-50 between the two men.

The company’s income actually comes from Pelican Marine Distributors, a Belle Chasse firm that supplies food, bedding, janitorial items and other equipment to companies that work in the Gulf. CTNN gets a commission, paid by Pelican Marine, for all items ordered by Harvey Gulf.

According to sources with knowledge of the investigation, Harvey Gulf is the only company for which CTNN receives such commissions. The company has no presence on the internet or any other apparent visibility, such as a storefront.

The sources said federal subpoenas for records have been served on Normand, Taffaro, Harvey Gulf and Pelican Marine. Normand and Taffaro, as well as at least one official from Pelican Marine, have been interviewed by agents.

Both the FBI and the Internal Revenue Service are involved in the probe.

Walter Becker, a former federal prosecutor who represents Normand, declined to comment. Taffaro did not return messages left by The Advocate. Normand also did not return a call seeking comment.

Ralph Capitelli, an attorney for Guidry, did not return phone messages.

William Lazaro Jr., one of two owners of Pelican Marine, referred a reporter to his attorney, John Litchfield. “Our attorneys have advised my partner and I not to discuss it,” Lazaro said when asked about the probe.

Reached on Friday, Litchfield declined comment.

Lazaro and his partner, Jeffrey Badeaux, bought Pelican Marine in 2012, records show. The financial arrangement with CTNN had been put in place by the previous owners, the largest of whom was another prominent Louisiana politician: Billy Nungesser, who last year was elected lieutenant governor.

Taffaro is Nungesser’s father-in-law, although Nungesser did not marry Taffaro’s daughter until after the commission deal was in place.

Nungesser -- who told The Advocate on Thursday that he has not been interviewed by the FBI or received a subpoena -- said he had no involvement in setting up the arrangement among CTNN, Pelican Marine and Harvey Gulf.

“I have not” heard from federal authorities, Nungesser said. “I didn’t have any knowledge of this.”

Nungesser said his direct involvement with Pelican Marine ended when he became president of Plaquemines Parish in 2006. At that point, he said, he put all of his business interests into a blind trust and relinquished control to a trustee.

Taffaro eventually became the trustee, although it’s not clear whether Taffaro was in control of the trust when Pelican Marine’s deal with Taffaro’s firm began.

Guidry has long been a close ally of Normand’s, and he also was close to Normand’s mentor, longtime Jefferson Parish Sheriff Harry Lee. He has served as a reserve deputy with the Sheriff’s Office since the late 1990s.

Guidry also recently became a top aide to state Attorney General Jeff Landry, to whom he reports directly as a special assistant.

A Landry spokeswoman described Guidry’s mandate as “to cut costs and reduce waste at the office and ensure the LBI (Louisiana Bureau of Investigation) has the tools, staff, and support needed to efficiently and aggressively combat crime.”

Guidry, a multimillionaire, earns a minimal salary of $12.83 per hour in that role, and he works part time, meaning his annual pay will be roughly $12,000, the spokeswoman said. She added that Guidry donates his entire salary to Children’s Hospital.

Guidry told WWL-TV in a recent interview that he is taking the salary only to protect himself legally in case of a lawsuit. Guidry also told the station that he would not make any decisions about whom to investigate or prosecute.

Guidry and Normand served as co-chairmen of Landry’s transition committee. Guidry was also a major financial backer of Landry; he and his wife underwrote a $10,000 party for the candidate last year, records show.

Lazaro and Badeaux have been regular donors to Normand’s campaign war chest, giving $12,400 between them to the sheriff’s account since 2008.

Though he now holds a key position in the Attorney General’s Office, Guidry remains chief executive officer of Harvey Gulf.

Guidry took over the top job at the firm in 1997, just as his father, Robert, who had been the CEO, was preparing to serve as the government’s star witness against former Gov. Edwin Edwards.

In that role, the senior Guidry admitted that, over a period of about 14 months, he had paid $100,000 a month in cash bribes that were split among Edwards; Edwards’ son, Stephen; and gubernatorial aide Andrew Martin.

The bribes were payback for the governor’s help in getting Robert Guidry a lucrative riverboat casino license. Robert Guidry was the majority owner of the Treasure Chest casino in Kenner for three years, later selling his stake for $90 million to Boyd Gaming, which operated the casino from its inception.

Prosecutors saw Robert Guidry’s testimony as so crucial to the case against Edwards that he was allowed to keep nearly all of his ill-gotten gains and never had to spend a day in prison.

Follow Gordon Russell on Twitter, @GordonRussell1.