A one-star Navy admiral will plead guilty today to lying to federal investigators in the “Fat Leonard” corruption scandal, his attorney said, which would make him the highest-ranking officer so far to be convicted in the case.

Rear Adm. Robert Gilbeau, a special assistant to the chief of the Navy Supply Corps, is scheduled to appear in U.S. District Court in San Diego late Thursday afternoon, court records show. He will plead guilty to one count of making a false statement to investigators, said David Benowitz, his defense attorney.

“In this unfortunate situation, he accepts responsibility for the decisions he made and for his conduct,” Benowitz said in an email to The Washington Post.

In the modern history of the Navy, only a handful of admirals have faced criminal prosecution. Just one admiral has been court-martialed since the end of World War II. A few others have been charged with crimes by civilian authorities shortly after they retired from the service.

Benowitz did not elaborate on the nature of the allegations against Gilbeau. Documents in the case were not publicly available before the admiral’s scheduled appearance in court Thursday.

Capt. Amy Derrick, a Navy spokeswoman at the Pentagon, said that the Justice Department had informed Navy leaders that Gilbeau would plead guilty Thursday. She said she had no information about the details of the plea agreement.

Several individuals familiar with the investigation told The Post last month that Gilbeau was under scrutiny by the Naval Criminal Investigative Service for his ties to Leonard Glenn Francis, a Singapore-based defense contractor who pleaded guilty last year to bribing scores of Navy officials.

Gilbeau, 55, came to know Francis – known in maritime circles as “Fat Leonard” for his girth – during several deployments to Asia and was also under investigation for his relationships with other contractors when he served in Afghanistan in 2012 and 2013, according to the individuals familiar with the investigation.

Gilbeau departed Afghanistan shortly after Francis, 51, was arrested in an international sting operation in San Diego in September 2013.

Francis has since admitted to bribing Navy officials with cash, sex and gifts worth millions of dollars so he could win more defense contracts. His company, Glenn Defense Marine Asia, provided critical support for the Navy’s 7th Fleet for a quarter-century by resupplying and refueling submarines and ships in ports throughout Asia.

The investigation has become perhaps the biggest corruption scandal to strike the Navy. A federal prosecutor said last year that 200 individuals were under investigation. Of those, about 30 are admirals, Navy officials have said.

Including Gilbeau, 14 people have been charged so far in federal court; all but one have pleaded guilty. In addition, a former Navy contracting official has been charged with corruption by Singapore authorities.

Gilbeau is a 1983 graduate of the Naval Academy in Annapolis. He was awarded the Purple Heart and the Bronze Star for his service in Iraq in 2007.

In a statement, Adm. John Richardson, chief of naval operations, said Gilbeau’s “behavior is inconsistent with our standards and the expectations the nation has for us as military professionals. It damages the trust that the nation places in us, and is an embarrassment to the Navy.”

He said the Navy is fully cooperating with the Justice Department. But in strongly worded comments, he also indicated that the Navy’s leaders needed to do more to police themselves.

“We must go further,” he added. “We must hold ourselves accountable to the highest standards of behavior, and work tirelessly to restore any damage that has been done to these crucial relationships.”

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