(Reuters) - A former U.S. Navy admiral at the center of a massive bribery scandal was sentenced on Wednesday to 18 months in prison for choosing “karaoke over character,” U.S. prosecutors said.

FILE PHOTO - U.S. Navy Rear Admiral Robert Gilbeau is seen in an undated official picture from the U.S. Navy. Courtesy U.S. Navy/Handout via REUTERS/File Photo

Former U.S. Navy Rear Admiral Robert Gilbeau, 56, of San Diego, pleaded guilty last year to lying when he told federal agents he had not received gifts from Malaysian businessman Leonard Francis, the owner of a Singapore-based defense contractor.

Gilbeau, who became the first active-duty admiral ever convicted of a federal crime, was subsequently demoted to captain.

Gilbeau’s case is part of a long-running criminal probe known as the Fat Leonard case, in reference to a nickname for Francis.

“It is truly a somber day,” acting U.S. Attorney Alana Robinson said in a statement. “When tempted by parties and prostitutes, one of our most respected leaders chose karaoke over character.”

Gilbeau is free on bond and was ordered to report to the U.S. Bureau of Prisons on June 23. In a plea agreement with prosecutors, Gilbeau previously agreed to pay $50,000 in restitution to the Navy as well as a $100,000 fine

Gilbeau’s attorney, David Benowitz, said his client accepted responsibility for making false statements, but denied inflating any invoice or accepting money for doing so.

“We respectfully disagree with the court’s sentencing decision, given Captain Gilbeau’s otherwise stellar 37 years of service to his country, during which he was awarded a Bronze Star and Purple Heart,” Benowitz said in an email.

U.S. District Judge Janis Sammartino said Gilbeau deleted documents and data files as he tried to conceal his dealings with Francis, according to a U.S. Department of Justice statement.

“You dishonored your shipmates, the Navy and the United States of America,” Sammartino told Gilbeau at a federal court in San Diego according to the Justice Department statement.

Gilbeau’s business relationship with Francis actually dated back to 1997, during which Francis plied Gilbeau with expensive gifts ranging from fine dining, luxury hotels and prostitutes, prosecutors said.

Gilbeau was in his mid-30s when he first met Francis in Bali, Indonesia, and the parties with prostitutes started right away, prosecutors said.

In return, Gilbeau signed off on contracts for services such as removing waste from U.S. aircraft carriers at highly inflated prices, prosecutors said.

Francis was arrested in September 2013 on fraud and bribery charges. He faces up to 25 years in prison after pleading guilty in January to bribery and conspiracy charges, prosecutors said.

Twenty current and former Navy officials have been charged so far in the fraud and bribery investigation, prosecutors said. Ten of those have pleaded guilty and 10 cases are pending. Also, five executives from Francis’ company, Glenn Defense Marine Asia, have pleaded guilty.