The FBI investigation into fraud amid off-duty details by Orleans Parish Sheriff’s Office deputies has implicated Gerald “Jerry” Ursin, the veteran lawman who serves as Sheriff Marlin Gusman’s chief deputy and right-hand man, according to sources familiar with the inquiry.

Ursin, who is expected to face federal charges in the coming days, is accused of conspiring with Roy Austin, a retired Sheriff’s Office colonel, to overbill local businesses that hired off-duty deputies to provide security at major sporting events and music festivals in the city, including the 2013 Super Bowl.

Austin was charged Friday with one count of conspiracy to commit wire fraud in a scheme that began in 2009 and is said to have involved some $83,000 in “fraudulently inflated charges.”

Austin, who coordinated details through his private company, Austin Sales and Service, padded invoices with billings for “ghost employees,” deputies who did not actually work the events, according to federal prosecutors. He then kept the extra money for himself, court documents say.

Austin and Ursin are expected to be mentioned in an investigative audit being finalized by the Legislative Auditor’s Office, a long-awaited report that is expected to outline the detail scheme as well as other improprieties within the Sheriff’s Office that have been flagged for criminal investigation. The audit, which could be published as soon as next week, refers multiple times to the chief deputy of the Sheriff’s Office, the sources said.

The involvement of Ursin thrusts the scandal into Gusman’s inner circle, though none of the sources has indicated the sheriff himself will face any criminal charges.

Gusman, who remains embroiled in contentious litigation over conditions at the city’s jail, has refused to comment on the allegations of fraud, telling a reporter last week he has “nothing to say” about the case.

The Sheriff’s Office has sought to distance itself from the federal inquiry, issuing a statement last week that the off-duty details are “independent of OPSO business and related to a private business that Austin allegedly created.”

Ursin, once second-in-command at the New Orleans Police Department, has been a polarizing presence within the Sheriff’s Office, often finding himself at the center of controversy.

Just last month, Carmen DeSadier, the sheriff’s ranking deputy at the Orleans Justice Center, resigned her position amid a power struggle with Ursin that DeSadier claimed was preventing the Sheriff’s Office from implementing court-ordered jail reforms.

“His abrasive tactics, questionable practices and bullying of personnel who attempt to work with me has created an atmosphere of fear and disdain,” DeSadier wrote in her Feb. 19 resignation letter. “This agency would be better served without his contemptuous influence.”

Ursin and his defense attorney, Pat Fanning, did not return calls seeking comment Monday.

Asked last week whether he was in the FBI’s crosshairs, Ursin said, “Not that I know of,” but he declined to answer other questions.

Ursin’s alleged role in the detail skimming scheme was outlined in the bill of information federal prosecutors filed Friday charging Austin, which referred to Ursin as Sheriff’s Office “Employee A,” in keeping with Justice Department guidelines that frown on accusing named people of crimes when they have yet to be charged.

Use of a bill of information rather than an indictment suggests that Austin has signed a plea agreement and is cooperating with the government. Austin’s defense attorney, Bob Habans, declined to comment Monday on Ursin’s possible involvement.

According to the bill of information, “Employee A” received a share of the money Austin overbilled, including some checks made to the employee’s “family members under the fraudulent guise of payments for detail work that in fact did not take place.” The defrauded businesses included a number of unnamed Mardi Gras krewes that hired large security forces for special events, the document says.

“Austin and OPSO ‘Employee A’ then either fraudulently endorsed those checks or, in some instances, had their respective family members endorse the checks for subsequent deposit,” the bill alleges.

The document also describes a $360 check Austin gave “Employee A” in April 2010 “for allowing Austin to run the day-to-day operation of the (details) scheme.”

The documents charging Austin do not make clear how the $83,000 in billings that prosecutors describe as fraudulent were split among Austin, Ursin and possibly others.

Ursin’s ethics have been called into question in the past, even before DeSadier, in her resignation letter, accused him of belittling subordinates “to make himself appear superior and to feed his obsession to exercise authority over others.”

In 2003, when Ursin retired from the New Orleans Police Department, he was facing a demotion amid allegations that he misled the department about having an undergraduate degree he never earned.

Last year, a Sheriff’s Office employee filed a federal lawsuit claiming Ursin had called him a racial slur, but the case was thrown out in January.

A 2013 report by The Lens raised questions about the business relationship between the Sheriff’s Office and an office supply company owned by Raymond Schlaudecker. Schlaudecker’s brother Richard worked as a sales representative for Metro Business Supplies and was married to Ursin’s daughter Christina Ursin-Schlaudecker.

The Lens found that Metro’s billings to the Sheriff’s Office grew significantly in 2008, the year Ursin was hired there. A Gusman spokesman denied that the business had been afforded favorable treatment.

Austin and Ursin are not the first Sheriff’s Office employees to face FBI scrutiny on Gusman’s watch. John Sens, the former purchasing manager at the Sheriff’s Office and brother of Municipal Court Judge Paul Sens, admitted to a kickback and bid-rigging scheme involving at least two contractors who did work for the Sheriff’s Office.

Sens was sentenced to five years in prison in connection with that scheme. Gerard Hoffman Jr., the sheriff’s former maintenance head, received probation.

Staff writer Gordon Russell contributed to this report. Follow Jim Mustian on Twitter, @JimMustian. Follow Mike Perlstein, @MikePerlstein.