Buenos Aires: The death of the prosecutor who accused President Cristina Fernandez of concealing the involvement of Iran in a deadly 1994 terrorist attack on a Jewish cultural centre in Buenos Aires sent shockwaves across Argentine society.

Alberto Nisman, 51, was found shot to death early Monday, hours before he was due to appear before Congress to present his reasons for seeking to indict the president, Foreign Minister Hector Timerman and five other people in connection with 85 deaths in an explosion at the offices of the Jewish organisation AMIA.

Police confirmed that the fatal shot came from the .22-caliber pistol found under Nisman’s body inside a locked bathroom at his home in the capital’s Puerto Madero neighbourhood.

The body was discovered by Nisman’s mother, who needed the services of a locksmith to enter the bathroom.

No note was discovered.

Nisman, who told associates that he feared for his life, had a 10-member security detail.

Fernandez was immediately informed of Nisman’s death, aides said.

Her cabinet chief, Jorge Capitanich, expressed the administration’s support for the security forces “to guarantee the clarification” of the “painful event.”

Timerman, who is in New York for a meeting of the UN Security Council, expressed regret over “the death of a human being”, and said he was confident the Argentine justice system would get to the bottom of what happened.

Though she has made no public statements about Nisman’s death, Fernandez ordered Argentina’s intelligence agencies to declassify all materials pertaining to the probe of the car-bomb attack on AMIA.

The order applies to all information derived from the wiretaps that Nisman said provided the key evidence against Fernandez and the others, Intelligence Secretary Oscar Parrilli said.

Argentina’s federal judiciary is currently in recess, but Judge Ariel Lijo interrupted his vacation to process Nisman’s accusation against the president and take steps to secure all evidence that was in the prosecutor’s possession.

Buenos Aires Mayor Mauricio Macri, a presidential hopeful and bitter political foe of Fernandez and her late husband and predecessor, Nestor Kirchner, urged the justice system to act “independently, quickly and decisively” in the investigation of Nisman’s death.

“I am dismayed. This appears to me to be something absolutely grave,” said opposition lawmaker Patricia Bullrich, who had invited Nisman to appear before Congress.

Meanwhile, a call went out on social networks for Argentines to gather Monday night in the square outside the presidential palace for a rally under the banner “Yo soy Nisman” (I Am Nisman).

The charges against Fernandez and Timerman were based on intercepts of telephone conversations about efforts “to erase Iran from the AMIA case,” Nisman’s office said last Wednesday in a statement.

The government wanted to eliminate any obstacle to forging closer trade and economic ties with Tehran, the prosecutor said.

Timerman — himself a member of Argentina’s Jewish community — reacted angrily to the accusations, labelling Nisman a liar and saying that the prosecutor allowed himself to be unduly influenced by Jaime Stiuso, recently fired as chief of operations for the intelligence service.

Many in the Argentine Jewish community believe the AMIA bombing was ordered by Iran and carried out by Tehran’s Hezbollah allies.

Both the Iranian government and the Lebanese militia group deny any involvement and some have pointed out that the accusation relies heavily on information provided by the CIA and Israel’s Mossad spy agency, both with an interest in blackening the reputation of Tehran.

To the indignation of many, both in Argentina and abroad, prosecutors have yet to secure a single conviction in the case.

In September 2004, 22 people accused in the bombing were acquitted after a process plagued with delays, irregularities and tales of witnesses being paid for their testimony.

The attack against the AMIA building was the second terrorist strike against Jewish targets in Argentina. In March 1992, a car bomb was detonated in front of the Israeli Embassy in Buenos Aires, killing 29 people and wounding more than 100 others.