He was "a double agent working for Iran"; he was "responsible for the botched operation in a Dubai hotel in 2010" in which Mossad agents killed a senior Hamas commander; he was "just a loud mouth who couldn't keep quiet" about being a member of Israel's secret service. These are some of the many theories about why Ben Zygier, or "Prisoner X" as he was known until last week, was held in Israel's most secure prison for a few months before apparently killing himself in December 2010. His detention was kept so secret that even his guards didn't know his name; his presumed crime so grave that even his family haven't gone public about his case.
Zygier's name, and indeed his existence, would not have been known had it not been for an investigation by Foreign Correspondent, a programme produced by Australia's ABC television, which unearthed details about the Israeli-Australian. They disclosed that his body was returned to his native Melbourne just before Christmas (and just after the birth of his second daughter) in 2010.
What Foreign Correspondent did not reveal was why Zygier was secretly jailed, a void that the Israeli government has not been eager to fill. So what exactly did this keen Zionist, a volunteer in the Israeli army, do to warrant such treatment? He was held in solitary confinement in the cell designed for Yigal Amir, the killer of the then Israeli Prime Minister, Yitzhak Rabin, and had access to nothing but a few books. Even Australian officials in Canberra admitted last week that they were unaware of Zygier's case, despite his status as an Australian national.
The lack of official information has inevitably been filled by speculation. Because of the timing, the first theory was that Zygier had been involved in the operation in Dubai to kill the Hamas agent Mahmoud al-Mabhouh in January 2010. Zygier was arrested just a month later.
Several countries were outraged when it was revealed that some of the Mossad agents had travelled on fake passports – indeed, Australia expelled an Israeli diplomat in the aftermath. Was Zygier responsible for the images of Mossad agents being captured by CCTV? Was he responsible for bungling the passports? Or, more seriously, did he get turned by domestic security agents, as a Kuwaiti newspaper suggested last week?
One of the men who took part in the Dubai mission was Joshua Daniel Bruce, almost certainly an alias. The picture in a forged passport identifying Bruce appears to be of a man about the same age as the then 34-year-old Zygier, and of the 26 suspects he bears the greatest resemblance to Zygier. But on Friday a forensic facial recognition report commissioned by Reuters showed that Zygier and Bruce are not the same person, but it does not entirely dismiss the idea that Zygier was somehow involved in the Mabhouh operation.
At the beginning of 2010, the Australian journalist Jason Katsoukis uncovered evidence that Zygier was one of three Israeli-Australians running a front company in Italy, which ostensibly sold electronic equipment, to Iran among others. Zygier denied being a Mossad agent when asked by Mr Katsoukis, but it seems likely that he was working on contacts within the Sunni group, Jundallah, which has launched attacks against the Shia Iranian government.
Could Zygier's incarceration be linked in some way to the arrest in February 2010 of Abdolmajid Rigi, the leader of Jundallah? Did Rigi blow Zygier's cover and tell Iranian officials about the operation in Italy? In an interview with the Iranian Press TV after his arrest, Rigi said that American and Israeli agents were trying to persuade Jundallah to take their fight to Tehran. Rigi was eventually hanged, but what did he tell the authorities in Iran first?
Even if Zygier had compromised Rigi, would that have warranted the tough treatment Zygier received? Moreover, while the Israeli government will never comment on the cases, there is evidence to suggest that it has had a hand in the deaths of a number of leading Iranian nuclear scientists, some killed in their cars as they travelled to work; a grisly, if nonetheless successful way of checking Iran's nuclear progress.
Did Zygier deliberately, or inadvertently, feed information about Mossad operations to Iran, or other hostile countries? Was he a fully fledged double-agent? Was he feeding information about Israeli operations back to officials in Australia – it certainly seems as though one official at the Australian embassy in Tel Aviv knew about Zygier's activities and he was known to Australia's secret service agents.
The answer to all these questions is that we don't know. Little information has leaked out and even those closest to Zygier seem unprepared to speak. What we do know is that whatever he did, it ultimately cost him his life.