Identifying the man only as the Hebrew equivalent of John Doe, the court order said a judge ordered an investigation into his death. About six weeks ago, the court statement said, the investigation concluded that he committed suicide. However, a judge has now asked the state to check for possible negligence.

In another curious wrinkle in the case, Israeli TV reported that Zygier had worked as a clerk in the international business department of one of Israel’s most prestigious law firms, Herzog Fox & Neeman. The firm is partially owned by Israel’s Justice Minister, Yaakov Neeman.

Neeman has told parliament he knew nothing of the case but said any allegations, if true, should be investigated.

Australian legislators, meanwhile, demanded answers about the suspicious death.

Shadow Foreign Affairs Minister Julie Bishop told ABC she wanted to know why details of the case were being censored in Israel. She said she would raise the issue with the Israeli Embassy.

Information about the case emerged briefly in June 2010, when the Israeli news site Ynet reported on the existence of Prisoner X. The report was mysteriously removed from the site shortly after it was posted, apparently under pressure from Israel’s military censor. The censor has authority to block or delete reports deemed threatening to national security.

Ynet then reported on Dec. 27, 2010, that a prisoner had committed suicide while in solitary confinement two weeks earlier. That report was also quickly removed.

The Israeli censor’s office declined comment.

A death notice published online from December 2010 announced the funeral for Ben Zygier. He is listed as the son of Geoffrey Zygier, the executive director of the B'nai B'rith Anti-Defamation Commission based in Melbourne.

Zygier’s father and his uncle, Willy Zygier, declined to comment on Thursday.

This is not the first alleged case of Israeli espionage involving an Australian passport. In May 2010, Australia ordered the expulsion of an Israeli diplomat after investigators concluded Israel was responsible for forging four Australian passports used by those responsible for the 2010 killing of a Hamas operative in Dubai.

At the time, Australia’s then-Foreign Minister Smith said Israel had previously forged other Australian travel documents. He did not elaborate, but said the 2010 transgression breached ‘‘confidential undertakings’’ between the two countries that have stood for several years.

The affair caused strains in an otherwise very close relationship between the two countries.

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