Zygier’s family, including his wife in Israel, have refused to speak to reporters and said they wanted to be left alone. In one of the few pictures posted online of his wife and two children, a caption from December read, "Finally, in happier times." Israeli reporters have kept the wife’s identity secret to protect the family’s privacy.
His family in Australia was said to have been "devastated" by his death. His parents, who’d worked as Jewish community organizers in Melbourne, quit their jobs shortly after he died. Local Australian papers said the family had completely withdrawn after the funeral, and the once-active members of the community are now rarely seen.
What could Zygier have done to frighten his family and the state of Israel into utmost secrecy?
The Australian newspaper The Age ran a report Wednesday saying that at the time of his death, Zygier was under investigation by the Australian Security Intelligence Organization, which suspected him of using his Australian passport to spy for Israel.
The newspaper said he was one of several individuals who’d raised suspicion by asking for new passports with more "Anglo"-sounding names after they’d immigrated to Israel.
"The men had used the new passports to travel to Iran, Syria and Lebanon – all countries that do not recognize Israel and do not allow entry to Israelis, or anyone with an Israeli stamp in their passport," the newspaper said.
The Mossad has long relied on Jewish immigrants with foreign passports. One former Mossad agent recalled in an interview with McClatchy last year that the Mossad often recruited immigrants from “attractive Western countries" as agents if they were deemed to have appropriate "profiles."
The former agent, who’d agreed to talk to McClatchy on the general topic of Mossad recruitment of foreigners only if his identity were kept secret, said such recruits might be assigned to a wide variety of tasks.
Some were asked to use their passports to rent apartments or purchase cars in foreign countries, he said. Others might become more active members who undertook delicate international missions.
It’s unclear what role Zygier had in the Mossad. Various theories have suggested that he was a double agent, that he’d been caught using his Australian passport to spy for Israel and was being pressed to spy for Australia as well. Other reports have speculated that he was caught selling secrets to the Iranians or one of Israel’s other regional enemies.
"He did something that went to the highest level of state security and which required him being kept alive but in absolute isolation. That is all I can tell you," said one senior Israeli defense official, who said he was privy to some details of the case but couldn’t risk violating the gag order. He asked that he not be identified.
Officials at Ayalon prison, where Zygier spent nearly a year in isolation, refused to comment.
Zygier was kept in a cell known as Wing 15 that had been designed for Yigal Amir, the man who assassinated Prime Minister Yitzhak Rabin. Ari Shamay, a lawyer for Amir who visited him once in the cell, described it as a "four-by-four room, with next to nothing inside but a bed, shower and toilet."
Cameras were fixed on the room and monitored 24 hours a day. Reports in Israeli newspapers have said the room had special sensors that monitored temperature and even heartbeat, though Israeli officials wouldn’t confirm those details.
Israeli human rights groups have begun asking how, under those conditions, a prisoner manages to fashion a noose and hang himself before guards are able to intervene.
On Wednesday, Israeli blogs speculated that the story of Zygier’s suicide was yet another cover-up, designed to disguise a more gruesome death.
In the end, they concluded, Zygier may have taken his secrets with him to the grave.