Zygier, with his blond hair, blue eyes and Australian passport, wouldn’t have raised a lot of suspicion.

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.

He “may well have been about to blow the whistle, but he never got the chance," Fairfax Media reported, quoting what it described as an Australian security official with knowledge of the case. Fairfax publishes Australia’s two largest newspapers, The Sydney Morning Herald and The Age..

After a visit to Australia, Zygier was arrested in Israel in February 2010. Australian newspapers have reported that Israel informed Australia’s secret service of the arrest on Feb. 24, 2010, eight days after Dubai police revealed that Mossad agents had used foreign passports – including Australian and British – to enter Dubai and assassinate a leading official of the Hamas movement, Mahmoud al Mabhouh.

One Israeli official familiar with the case, who spoke to McClatchy on the condition that he not be identified because of the gag order, confirmed that Zygier had intended to reveal sensitive details about the Mossad’s use of foreign passports that would have harmed Israel’s diplomatic relations with Western countries.

"Its unclear how far he went and therefore what the crimes were that he is being accused of committing," he said.

The official version of Zygier’s death – that he hanged himself in his cell on Dec. 15, 2010 – is being greeted with widespread skepticism as details about his life become known.

At the time that he allegedly killed himself, three district judges appointed to try his case were deliberating on a verdict. Several prominent lawyers were defending Zygier, and Avigdor Feldman, a prominent attorney who’d previously represented Mordechai Vanunu – who was accused of leaking secret information about Israel’s nuclear program – said Zygier was aware of his rights and determined to fight the charges leveled against him.

"He wanted to clear his name," said Feldman, who’d presented Zygier with a possible plea-bargain deal. “He was very rational and focused. He did not seem suicidal."

Feldman wouldn’t reveal the terms of the plea bargain, but he said Zygier had felt that it burdened him with crimes he didn’t commit.

Israeli human rights groups have begun pressing the government for details on Zygier’s death. They note that numerous reports show that he wasn’t suicidal. They also express wonder that he managed to kill himself in Israel’s highest-security prison, where he was under constant surveillance.

He died six days after his 34th birthday, and only four days after the birth of his second daughter. The cell he was confined in was outfitted with specialized cameras and sensors that could monitor his heartbeat and temperature, specifically designed to prevent a prisoner from harming himself.

Some Israeli newspapers have reported that Ayalon prison took hours to call medics once officials learned Zygier had attempted suicide and that prison medics didn’t try to resuscitate him. Australian papers have suggested a perhaps more nefarious ending, asking whether the suicide wasn’t a cover-up for a more gruesome death.