The Australian prisoner who reportedly committed suicide in an Israeli jail in 2010 was at one point investigated by Australia’s national security service, which suspected him of using his dual citizenship to spy for Israel, an Australian news site reported on Wednesday.

Ben Zygier, a native of Melbourne, had traveled across the Middle East, including to Iran, Syria and Lebanon, and was suspected of aiding in the assassination of a top Hamas official, Mahmoud al-Mabhouh, the Sydney Morning Herald reported.

According to an Australian television report aired on Tuesday, Zygier was a Mossad agent. Guards reportedly found him hanged in Ayalon Prison in Ramle in 2010, and the case became known as the “Prisoner X” affair.

Zygier reportedly studied at Melbourne’s Monash University in order to mingle with students from Arab countries, including from Saudi Arabia and Iran, the Herald reported.

Zygier and two others were also investigated for possible involvement in the alleged assassination of Mabhouh, a senior Hamas operative who was found dead in his hotel room in Dubai, a 2010 report by The Age said. A number of people, including Dubai’s police chief, pointed a finger at the Mossad for Mabhouh’s death.

At least three of the people suspected of involvement in the assassination traveled under Australian nationality, the Dubai police said after the incident. However, at the time (Australian Security Intelligence Organisation) ASIO did not uncover evidence linking Zygier to the assassination, the Herald said.

The investigative report aired on Australia’s ABC network on Tuesday and immediately caused political and diplomatic shock waves.

A number of Israeli MKs questioned the legality and morality of the reported decision to keep information regarding Zygier under wraps.

Zahava Gal-on (Meretz) protested what she termed “the undemocratic process by which journalists volunteer to censor information at the behest of the authorities.” She said gag orders should be applied only when there was a clear threat to national security, and protested that news editors were given information that was being withheld from members of Knesset.

Australian deputy opposition leader Julie Bishop met on Wednesday with Israeli Ambassador Yuval Rotem to discuss the “Prisoner X” episode and the reported Israeli censorship of the case.

Australian Foreign Affairs Minister Bob Carr ordered an investigation after it became clear that the Australian Embassy in Tel Aviv had been informed of Zygier’s jailing, but the information had not been transferred to the proper channels, according to Australian press reports.

Carr said that his office only became aware of the prisoner’s existence when the Zygier family asked for assistance in bringing his body back to Australia.

“The Australian Embassy in Tel Aviv was unaware of this Australian’s detention until his death was reported by his family, who requested repatriation of his remains,” Australia’s Department of Foreign Affairs and Trade confirmed in a statement Wednesday. “The family has not asked for any further representations.”

The probe that Carr demanded on Wednesday is to determine why that information was not passed on at the time.

According to the report on Australia’s ABC television, Zygier went by the alias Ben Alon in Israel. The channel reported he hanged himself in a cell that had been specially designed for Yigal Amir, who assassinated prime minister Yitzhak Rabin in 1995.

The Australian station reported that Zygier emigrated to Israel in 2000 and was 34 years old when he took his own life on December 15, 2010. He was married to an Israeli woman with whom he had two children.

Zygier also held an Australian passport under the name Ben Allen, according to the report.