A senior law enforcement agent accused of taking bribes in a Navy corruption scandal has agreed to plead guilty and cooperate with investigators, a major break in a case that has ensnared half a dozen Navy officers and threatens to tar more.

John B. Beliveau II, a supervisory special agent with the Naval Criminal Investigative Service, is scheduled to enter a guilty plea Tuesday in federal court in San Diego, according to court records and his attorney. Beliveau was arrested in September and charged with helping a Singapore-based Navy contractor, Glenn Defense Marine Asia, dodge multiple criminal investigations by leaking inside information about NCIS probes in exchange for prostitutes, cash and other favors.

“He will be pleading guilty and admitting his conduct,” said his attorney, Gretchen Von Helms of San Diego. She declined to comment further, saying that terms of his plea deal would remain confidential until he appears in court next week.

Kelly Thornton, a spokeswoman for the U.S. Attorney’s Office in San Diego, confirmed that Beliveau is scheduled to appear in court Tuesday for a change-of-plea hearing but declined to comment further.

Two people involved in the case, speaking on the condition of anonymity because details have not been presented in court, said Beliveau had agreed to share information with federal prosecutors about his extensive relationship with Leonard Glenn Francis, president of Glenn Defense Marine and a co-defendant in the case, as well as others involved in the investigation.

Read court filings

Glenn Defense Marine and its president, Leonard Glenn Francis, are principal characters in one of the biggest contracting fraud investigations in the Navy's 238-year history, with accusations of bribes involving prostitutes and cash. Explore the government's evidence.

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Known in Navy circles as “Fat Leonard” for his imposing physical presence, Francis is a Malaysian citizen and a well-known figure to scores of Navy officers whose ships depended on his firm for logistical support during Asian port visits. He has pleaded not guilty. One of his attorneys, David S. Black of Washington, did not return phone calls for this article.

Beliveau’s guilty plea would mark a big advance for investigators, who are trying to determine the scope of the alleged corruption involved in the awarding and administering of lucrative Navy contracts for port services in Asia.

In addition to Beliveau, two Navy commanders have been arrested and charged with taking bribes. Two captains have been suspended or reassigned by the Navy, and two admirals who work in Navy intelligence have had their access to classified materials suspended while investigators scrutinize their possible involvement.

Navy officials previously have said that they expect more officers will be implicated. Beliveau’s agreement to cooperate with investigators raises the likelihood that others will be drawn into the scandal.

According to charging documents filed by prosecutors, Beliveau helped to thwart multiple fraud investigations into Glenn Defense Marine by surreptitiously copying sensitive records from the case files of other NCIS agents and feeding the details to Francis.

From 2005 through 2008, Beliveau served as a protective service agent for the commander of the Navy’s 7th Fleet, based in Japan. From 2008 until 2012, he was stationed in Singapore, where he was responsible for meeting Navy ships and arranging protection for their visits.

It’s unclear when Beliveau first met Francis, but the charging documents state that the two were in “regular contact” over the past five years.

In 2010, the NCIS opened two separate fraud investigations into suspicions that Glenn Defense Marine had overcharged the Navy for port visits in Thailand and Japan.

In both cases, according to prosecutors, Beliveau sent e-mails to Francis, tipping him off to developments in the probes and advising him on how to respond to agents’ queries. The investigations soon stalled, and Francis bragged in an e-mail to an associate that “both are hard to prove and charge. I have inside Intel from NCIS and read all the reports,” charging documents show.

In early 2012, NCIS opened another investigation into Glenn Defense Marine on suspicion that it was overbilling the Navy with fake subcontractor bids. Around the same time, Beliveau took a new NCIS job as a supervisory agent in Quantico, Va.

According to prosecutors, Francis once again turned to Beliveau for help. This time, however, Beliveau balked.

“I will always be your friend, but you will get nothing else . . . until I get what you promise,” Beliveau wrote in an e-mail to Francis in April 2012. “You give whores more money than me ;) . . . . Don’t get too busy that you forget your friends. . . . Let me know. . . . I can be your best friend or worst enemy.”

“You are a sore Bitch and I have not forgotten you Bro,” Francis replied. “[H]ow do I send you a gift?”

Days later, according to charging documents, Beliveau accessed NCIS databases and over the next three months downloaded or viewed dozens of confidential agent reports regarding the Glenn Defense Marine probes. All the while, Beliveau and Francis exchanged more than 100 text messages; investigators said they could not retrieve the texts because Beliveau used a prepaid phone and the carrier did not save the messages on its network.

According to the court records, Francis may have learned that NCIS agents had wired a cooperative witness with a microphone. In June 2012, five days after the NCIS had set up the witness with a wire, Beliveau searched the agency’s case database on Glenn Defense Marine for any mention of the term “oral wire intercept.” Although he found no records, the witness later “stopped responding to agent telephone calls and ultimately refused to participate further,” the court documents show.

Communications between Francis and Beliveau intensified later that year and into this year. The pair exchanged more than 1,100 text messages between May 2012 and August.

During the same period, according to a forensic examination of Beliveau’s government computer, the agent downloaded and saved 125 NCIS reports about Glenn Defense Marine Asia. In court papers, investigators said they believe Beliveau copied many of the reports onto compact discs and shared them with Francis.

Beliveau searched the internal NCIS database for files on Glenn Defense Marine one last time Sept. 9, court records show.

A week later, federal agents arrested Beliveau in Washington, Francis in San Diego and one of the Navy commanders in Colorado in a coordinated operation.