TEL AVIV, ISRAEL - In the space of three days, a two-year-old mystery about an unidentified prisoner who hanged himself in a high-security Israeli prison has become a scandal for Israel's vaunted Mossad spy agency.

The Israeli government now acknowledges that Prisoner X was an Australian citizen named Ben Zygier who was held in solitary confinement for eight months in the notorious Ayalon prison before he hanged himself. But the details of Zygier's life as a Mossad agent are still emerging, and with each new fact, analysts find a pattern of a spy agency that let down its guard and then perhaps went to extremes to cover up its responsibility.

"This is not an affair; it's a catastrophe," Uri Misgav wrote in the Israeli daily newspaper Haaretz. "The real issue is the state's spiriting away an Israeli-Australian citizen, who worked for it, and locking him up hermetically until he died in strange, suspicious circumstances."

Some wonder how a man whom friends described as a braggart who liked to show off that he was in the Mossad not only joined the spy agency but also likely turned into a double agent.

For two years, the Israeli government used its censorship authority to keep the story out of the headlines, banning mention of the suicide at Ayalon of an unidentified prisoner. The case was considered so sensitive that even mentioning the publication ban was prohibited.

But the details of Zygier's life have poured out since the government partially lifted the gag order in response to an Australian TV investigation into the case.

Records show that Zygier took advantage of an Australian law that allows citizens to change their names once a year. He took out at least three additional passports, using the names Ben Alon, Ben Allen and Benjamin Burrows. Zygier used those passports to travel to Iran and Syria, among other countries, and he applied for a work visa for Italy, according to public records in Australia.

Israeli officials have confirmed that "job" for the Mossad was probably to set up a straw company in Italy that sold electrical equipment to Iran. In those shipments, intelligence officials add, he could have sent other equipment necessary for Mossad operations in Iran.

In late 2009, it appeared that Zygier was on the verge of disclosing secrets about Israel's use of dual nationals in its spy operations. After a visit to Australia, Zygier was arrested in Israel in February 2010.