Zygier was accused of being a spy and died in mysterious circumstances in an Israeli jail in 2010.
One theory is that he was about to blow the lid on Israel's use of Australian passports.
That's an issue that New Zealand authorities know all about, after their own Israeli intelligence scandal several years ago.
But the response of the New Zealand Government to Israel stands in stark contrast to Australia's approach.
Presenter: Lexi Metherell
Speakers: Grant Illingworth, barrister; Opposition MP Phil Goff, New Zealand's former Foreign Minister
LEXI METHERELL: Ben Zygier was a dual Australian-Israeli national when he was imprisoned.
The Foreign Affairs Minister Bob Carr told today's Senate estimates hearing the Australian Government sought assurances from the Israeli government about his treatment, and it was told he was being treated within his lawful rights as an Israeli citizen.
Professor of International Law at the Australian National University, Don Rothwell, says the law is ambiguous but he would have still have had rights as an Australian citizen as well.
DON ROTHWELL: This particular issue does highlight this ambiguity that arises with respect to dual citizens and indeed Australia's recent experience with China in particular where we've faced a number of cases dealing with Australian dual nationals in China especially.
Stern Hu for example have just highlighted some of the difficulties that can sometimes arise in this matter which would suggest that there is a bit of a pattern of behaviour developing for Australia that when dual nationals are involved and when those dual nationals are located in the country of their other nationality, the Australian Government is not perhaps pressing as strongly as it might otherwise do to provide consular assistance and seek consular access to these individuals.
LEXI METHERELL: What more could it do to access them?
DON ROTHWELL: Well, quite clearly Australia can take a much more robust approach on these matters and directly refer to the obligations that other countries have towards Australia under the Vienna Convention on Consular Relations.
So not only make a diplomatic argument but also where necessary revert to the provisions of the relevant Vienna Convention on point.
LEXI METHERELL: Senator Carr says neither Mr Zygier nor his family requested consular support. But Professor Rothwell says irrespective of the family's position, the Australian Government has a responsibility to make sure its citizen's rights are upheld.
He questions whether Australia failed to do so because of its sensitive relationship with Israel.
DON ROTHWELL: The bilateral dynamic that exists between Australia in countries like Israel or countries like China may well be an impediment to Australia seeing that it can press its case very strongly and assertively through diplomatic channels when it's feeling that the rights of an Australian citizen are not being upheld, and indeed one can make the same argument in terms of Australia's dealings not necessarily with due nationals but in terms of Australian citizens being held by the United States during the so-called global war on terror.
LEXI METHERELL: Senator Carr told the Foreign Correspondent program which revealed Ben Zygier as Prisoner X that the Australian Government had no knowledge of his incarceration. Yesterday his department was forced to reveal it actually had known.
Further clarifying the situation, Senator Carr told today's estimates hearing the Government was alerted through intelligence as opposed to diplomatic channels in February 2010.
The impression left by the hearing is that the Australian embassy in Tel Aviv was not informed about Mr Zygier's situation.
A former official of Australia's overseas intelligence agency, ASIS (Australian Secret Intelligence Service) Warren Reid says normally, Australian intelligence officials would inform the highest levels of the relevant embassy.
WARREN REID: Probably only the ambassador would be briefed on it. Nobody else in the embassy would know, or no other Australian officials anywhere in Israel would know. That's quite standard so if you say sidelined, it wasn't that they were deliberately marginalised, it was that administratively, organisationally, functionally, it wouldn't be a thing that DFAT (Department of Foreign Affairs and Trade) would be handling. The ambassador would know but it is handled by the intelligence people. That's not odd, that's quite standard.
LEXI METHERELL: Would DFAT then open a file on the matter?
WARREN REID: Oh, at a very high level back in Canberra, yes. I mean it would go to, you know, to the highest level of the department, of Foreign Affairs and Trade and the minister would be immediately briefed on something like this.
LEXI METHERELL: How is it then that we had this fairly extraordinary situation where the Foreign Minister was saying last week that he had - the Government did not know about Ben Zygier's incarceration then yesterday we had the department saying well actually no, we did know in February 2010? How could that be explained?
WARREN REID: Well, firstly I thought the Minister's performance left a hell of a lot to be desired, just to make a side comment on that, with Senator Carr suggesting publicly that he couldn't do anything until perhaps the family wrote to him and asked him to trigger off an investigation was a rank insult to the family.
I mean the family in Melbourne and the friends of Ben and also his widow and two children in Israel, I mean haven't they been through enough already to have the Minister saying oh, if they write to me officially maybe I can do something.
There should have been a much better response on Bob Carr's part but I would not believe that his response was based on a briefing from DFAT because in DFAT there is an enormous amount of experience, a great corporate memory on how to handle super sensitive things like that.
If he'd been briefed by foreign affairs, we would not have seen the feeble performance that we saw.