JERUSALEM (CNN) -- An inmate who died in an Israeli prison was "found hanging in the shower of his security cell," a court document released Tuesday said, the latest detail to filter out of Israel in what has become known as the "Prisoner X" case.

The news emerged after an Israeli court lifted part of a gag order on the case. The document detailing the manner of death said that a sheet connected to the window of a bathroom was tied around his throat.

The case has stirred interest across the world.

The fate of the man dubbed "Prisoner X" is now the subject of an investigation by Israel's parliament. Prime Minister Benjamin Netanyahu pleaded over the weekend for details to be kept quiet, warning "overexposure of security and intelligence activity" could harm Israel's security.

The Australian Broadcasting Corporation has identified the prisoner as Ben Zygier, an Australian-Israeli dual citizen. It reported Tuesday that he had reported "every aspect of his work" for the Mossad, Israel's spy agency, to the Australian Security Intelligence Organization.

Zygier reportedly committed suicide in Israel's Ayalon Prison in December 2010, about 10 months after his arrest, according to ABC. His incarceration was a state secret, and Israel has never confirmed the prisoner's name or how he died.

ABC, citing unnamed sources, reported Tuesday that Zygier gave Australia "comprehensive detail about a number of Mossad operations, including plans for a top-secret mission in Italy that had been years in the making." Zygier helped Mossad set up a European communications company that sold electronics to Arab countries and Iran, according to the network.

He met with Australian intelligence during a trip back to Australia, ABC reported. It wasn't clear who approached whom -- but ABC said it "believes" Zygier was arrested after Mossad discovered his contact with ASIO, fearing he had given up Israeli secrets.