On Thursday, a lawyer hired by the family said he had met with Mr. Zygier a day or two before his death to discuss a plea bargain. “The crimes he was suspected of were serious,” the lawyer, Avigdor Feldman, told Israel’s Channel 10 news, refusing to elaborate. “He denied the charges,” Mr. Feldman added.

In a separate interview with Army Radio, Mr. Feldman said that Mr. Zygier, a lawyer who worked for a year at a prominent Israeli firm, “had been informed that he could very likely expect to be sentenced to an extremely lengthy prison term and to be shunned by his family — and this affects a person’s soul.”

It is unclear how a Mossad agent who had revealed details to a foreign government about an assassination, particularly one as fraught as the Mabhouh affair, would be eligible for a plea bargain. But if the secrets had not yet been shared, and they were limited to information regarding passport fraud rather than murder, a reduction in charges might be more realistic, experts said.

Mr. Feldman said that Mr. Zygier, who was 34 and whose second child, a girl, was born four days before his death, had not shown any suicidal signs. “He sounded rational and focused and he spoke to the point,” the lawyer told Army Radio. “He did not display any special feeling of self-pity.”

Mr. Feldman was one of many in Israel who called for further inquiry into Mr. Zygier’s death. “Those responsible for him should have taken clear steps to watch over him,” Mr. Feldman said.

In Australia on Thursday, the foreign minister revealed that his government had learned of Mr. Zygier’s detention on Feb. 24, 2010, contrary to an earlier ministry statement that it had been unaware until the family requested repatriation of his remains in late December. The minister, Bob Carr, declined to say whether the government knew the specific charges, saying only that officials were informed that Mr. Zygier had been detained “in relation to serious offense under Israeli national security legislation.”

Australia was one of several countries whose relations with Israel were strained by the revelations that the Dubai authorities made after the assassination of Mr. Mabhouh, a founder of Hamas’s military wing who played a role in the kidnapping and killing of two Israeli soldiers in 1989 and who helped supply Hamas with weapons from Iran.