Some Argentines are calling Alberto Nisman, the maverick prosecutor, the 86th casualty of one of the deadliest, unsolved terrorists attacks in modern history: the 1994 bombing of a Jewish community center in Buenos Aires. That seems fitting whether his death over the weekend turns out to be a suicide, as the government of President Cristina Fernández de Kirchner seems eager to establish, or the murder of a man who had learned too much.

This much is clear: The best hope of definitively establishing the truth about the horrific July 18, 1994, bombing and its tortured, politicized investigation is to impanel an international team of jurists who can take a fresh, objective look at the evidence.

The truth became more important after Mr. Nisman’s body was discovered inside his apartment on Sunday, hours before he was expected to testify on his startling allegation that Ms. Kirchner cut a deal with the Iranian government to protect some of the culprits of the attack.

Ms. Kirchner’s late husband, former president Néstor Kirchner, appointed Mr. Nisman to lead the inquiry a decade ago after acknowledging a shocking series of blunders by those assigned to the case over the years. Mr. Nisman, 51, became convinced that the bombing was carried out by the Shiite militant movement Hezbollah under orders of the Iranian government. Based on the prosecutor’s investigation, Argentina got Interpol to issue arrest notices for seven prominent Iranians, including a Hezbollah leader and several government officials.