Australian intelligence officials believe that Zygier, previously known as Israel's "Prisoner X," may have been ready to divulge details of Mossad operations — including the use of fraudulent Australian passports — when he was detained in January 2010, The Sydney Morning Herald reports.

The 34-year-old Jewish Australian ''may well have been about to blow the whistle, but he never got the chance," an Australian security official told The Herald.