Jerusalem (CNN) -- They call him Prisoner X.
Media reports have described him as a man who hanged himself in an Israeli prison cell. But details about what happened to him and why have long been hard to come by.
The case, shrouded in mystery, sparked a government gag order that for two years stopped local journalists in Israel from telling his story, according to local media reports.
For years, Israeli government officials repeatedly declined to comment on the prisoner's death, which was first reported by the Ynetnews website in 2010.
Now, a new report about the man many in the media have dubbed "Prisoner X" -- because his name was never revealed -- is sparking widespread debate in Israel over government censorship and about the country's prison system.
According to an investigative report this week from the Australian Broadcasting Corporation, which did not disclose its sources, Prisoner X was a dual citizen of Australia and Israel and was recruited to join Israel's Mossad spy agency. The report identified him as Ben Zygier, alleging he was detained in 2010.
Details about why he was reportedly held in a high-security prison outside Tel Aviv, and what led to his death, remain unclear, according to the ABC report.
"The case is regarded as one of the most sensitive secrets of Israel's intelligence community, with the government going to extraordinary lengths to stifle media coverage and gag attempts by human rights organizations to expose the situation," ABC Foreign Correspondent Trevor Bormann wrote.
Several prominent Israeli media organizations wrote stories about the Australian report but then were asked to remove stories about it from their websites by government censors, according to Israel's Haaretz newspaper and an editor to which CNN spoke.
A culture of censorship
All journalists who apply for a government-issued Israeli Press Card must sign documents agreeing to the military censorship. According to the agreement, journalists will not publish security information that could benefit Israel's enemies or harm the state.
Breaking the rule could result in card revocation, and foreign journalists could lose their visas to work there.
In recent years, the censorship mechanism for checking scripts and pictures has rarely been practiced. Controls over content have faded more and more with the Internet as more freedom of information passes into the public domain.
Israeli lawmakers voice concerns
But word of the Australian report and subsequent Israeli government censorship quickly rang out in the halls of Israel's Knesset, with some lawmakers sharply criticizing the government's handling of the matter.
"We hear, in a state that is supposed to be a proper democracy, that journalists are cooperating with the authorities without the high court ruling that the case is a certain and imminent danger to the security of the state," said Israeli Parliament member Zahava Gal-On, leader of the Meretz Party. "When unknown prisoners commit suicide and nobody knows who he is, how does that fit with a democracy with law which is proper?"
During the Knesset session, another lawmaker asked Israel's justice minister about the case, point blank.
"Do you know about this? Can you verify the fact that an Australian citizen committed suicide in an Israeli prison under a made-up identity and the fact was not published that he was a prisoner in a prison in Israel?" asked Ahmed Tibi, a member of the Knesset.
Justice Minister Yaakov Neeman said that the matter should be investigated but that he could not answer the questions "because the subject is not under the jurisdiction of the Justice Ministry."
On Wednesday, a district court in central Israel lifted part of the gag order and ruled that local media could quote foreign publications' reporting on the case but also said they could not do their own reporting on the story.
Later that day, a statement from an Israeli court appeared to publicly confirm details about the case for the first time.
The statement, released by the court in the partial lifting of the gag order, described a "prisoner who was both an Israeli citizen and a foreign national."
"The inmate was registered under a false identity for security reasons, but his family was notified immediately upon his arrest," the statement said.
The court document also said that the prisoner was found dead in his cell two years ago and that a judge ordered an investigation into his death.
The death was recently ruled a suicide, the statement said, and authorities are investigating whether there was negligence in the case.
Additional details cannot be revealed "for reasons of state security," the document said.
Lawyer: I spoke with prisoner shortly before his death
Human rights lawyer Avigdor Feldman said he met with the prisoner a day or two before he allegedly committed suicide.
At the time, Feldman said, the prisoner had not been tried or convicted but was indicted and in pretrial imprisonment.
"His wife asked me to go and see him and look into some legal questions which he had," Feldman said.
Feldman said he met with the prisoner "as a lawyer who was asked not really to represent him but to consider his legal options. It's quite common."
Feldman said that while he was not aware of the details of the cell, "it is supposed to be suicide-proof."
When asked why the prisoner was being held and reports about his dealings with Iran, Feldman answered, "I can't comment unless you want to come and visit me in prison."
One journalist shares his story
Most people worldwide first learned Prisoner X's name as news of the case surged this week.
But journalist Jason Koutsoukis said that an Australian intelligence source first told him about Ben Zygier in October 2009.
The intelligence source, Koutsoukis told CNN, identified Zygier and two other Australian citizens who were also Israeli citizens.
"(The source) suggested to me that they had been involved in a passport scam -- a means to change their identities in Australia and use the new travel documents they obtained to be able to go into countries that were sensitive for Israel," Koutsoukis said.
That issue was a particularly contentious topic between Australia and Israel in 2010, around the time when Zygier was reportedly detained.
Authorities in the United Arab Emirates at the time said that fake Australian passports had been used by three suspects who slipped into a Dubai hotel and killed a Hamas leader. And media and intelligence reports said Israel's Mossad was behind the attack.
Australia's foreign minister summoned Israel's ambassador, saying it was a matter of "the gravest concern."
Australia seeks answers
The latest developments in Prisoner X's case prompted Australian Foreign Minister Bob Carr to request an internal report.
"I'm advised in the form of an interim report that the Australian government was informed in February 2010, though 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," Carr told a Senate committee Thursday.
He did not mention what the alleged "serious offenses" were.
Carr said Australia sought specific assurances from Israel, such as that the detainee would get legal representation of his choosing and that he would not be mistreated.
"At no stage during his detention did the Australian government receive any requests from the individual or his family to extend consular support," Carr said.
"The Australian government was advised through intelligence channels on December 16, 2010, (of) this individual's death on the previous day, and the deceased's family had been notified by Israeli authorities," Carr said.
The Australian Embassy in Tel Aviv assisted in returning the body to Australia, Carr said.
Sharp criticism over secrecy
As authorities stay tight-lipped about details of the man's case, speculation continues to swirl.
The Association for Civil Rights in Israel said it sent a letter to Israel's attorney general about the case on Wednesday, criticizing the censorship and calling for the gag order to be scaled back further.
"What is far more concerning, of course, is the fact that a man was held in detention under heavy secrecy, and nothing was published about the reason for his arrest or the circumstances surrounding his death," wrote Dan Yakir, the association's chief legal counsel.
The letter argues that there is "considerable public interest" in more information about the investigation into the death of Prisoner X.
"Was it really suicide? Was there negligence in the supervision of the detainee? Has any official body taken responsibility? What steps have been taken to prevent the recurrence of similar events in the future?" Yakir asked.
Israeli government officials have made no further comments on the case.
CNN's Catherine E. Shoichet and Neda Farshbaf contributed to this report.