Australian newspapers lead their front pages in Australia on Feb. 14, 2013, with the story of Ben Zygier as Israel confirms it jailed a foreigner in solitary confinement. (WILLIAM WEST/AFP/GETTY IMAGES)

An Australian-Israeli citizen suspected of spying for Israel, who died while secretly held in an Israeli jail in 2010, had been charged with grave security crimes and was weighing a possible plea bargain, according to a lawyer who met with him shortly before his death.

The lawyer, Avigdor Feldman, said in a telephone interview Thursday that grave security crimes include espionage and treason, but he declined to say what the specific charges in the case were, citing a court-imposed gag order.

Australian media reported Friday that Australian security officials suspect that before his arrest, the man, identified as Ben Zygier, 34, may have been about to disclose — either to the Australian government or to media — information about Israeli intelligence operations, including the use of fraudulent Australian passports by the Israeli spy agency Mossad.

Zygier’s mysterious demise had been cloaked in extraordinary secrecy in Israel for more than two years, but a report by Australia’s ABC network on Tuesday led Israeli authorities to acknowledge the death late Wednesday after initially attempting to prevent local media from publishing the story.

A statement from the Israeli State Attorney’s office did not identify the prisoner — known in Israel as “Prisoner X” — or his nationality, saying only that he had Israeli and foreign citizenship and had been held under a false identity for security reasons. The statement added that the prisoner’s family was notified immediately of his arrest and that he had been represented by lawyers.

The prisoner was found dead in his cell about two years ago, and following a court-ordered investigation, the death was ruled a suicide six weeks ago, the statement said, adding that the case was being examined for possible negligence.

The ABC report said that Zygier, a native of Melbourne, had emigrated from Australia to Israel in 2000 and worked for the Mossad, and he was found hanged in a maximum-security cell in a prison near Tel Aviv in late 2010.

Feldman, who was not representing Zygier, said he had met with him for more than an hour in an isolation cell in December 2010 at the request of Zygier’s family, to advise him regarding a possible plea bargain. Zygier had been charged with serious security offenses legally defined as “grave crimes” and carrying sentences of more than 10 years, according to Feldman.

Zygier denied the charges, Feldman said, adding that “he was anxious about his future and thought he could be cleared in a trial.” The prisoner was concerned about the “social consequences” for his family if he were convicted and jailed under a plea-bargain arrangement, including the “disgrace and ostracism” that might follow.

Still, Feldman said, Zygier seemed focused on the next steps and was “thinking about the future,” so “it was a complete surprise” when news of his death arrived a day or two later.

An article published in February 2010 in the Australian newspaper the Age, at the time of Zygier’s arrest in Israel, said that at least three Australian-Israeli citizens were being investigated by the Australian intelligence service on suspicion of spying for the Mossad and using their passports to travel to Iran, Syria and Lebanon, countries that ban entry to Israelis.

The article said that the men had emigrated to Israel but returned to Australia at different times to legally change their names and get new passports. The men were not named, but a report Thursday in the Age said that Zygier was one of them and that he had emphatically denied being a spy when interviewed for the story.

The newspaper said that Israeli intelligence officials informed Australia’s intelligence agency of Zygier’s arrest eight days after authorities in Dubai, United Arab Emirates, announced on Feb. 16, 2010, that suspected Israeli agents had used fraudulent passports as part of the assassination there in January of Mahmoud al-Mabhouh, a senior operative of the Palestinian militant group Hamas. The suspects carried forged European and Australian passports, according to the Dubai authorities.

Foreign Minister Bob Carr told an Australian Senate hearing Thursday that the Australian government “was informed in February 2010 through intelligence channels that the Israeli authorities had detained a dual Australian-Israeli citizen — and they provided the name of the citizen — in relation to serious offenses under Israeli national security legislation.”