A member of the Islamic militant group Hezbollah was the suicide bomber who blew up a Jewish community centre in Argentina in 1994, say prosecutors.
More than 200 people were wounded in the Jewish centre blast
Ibrahim Hussein Berro, 21, of Lebanon, was identified in a joint effort by Argentine intelligence and the FBI, said prosecutor Alberto Nisman.
Islamic militants, backed by Iran, have long been suspected of carrying out the attack that killed 85 people.
Argentina's Jewish community has for years sought a resolution to the case.
Mr Nisman said Hussein had been identified by FBI and Argentine intelligence, and corroborated by at least three witnesses.
He showed reporters a picture of the supposed bomber, a young man with heavy eyebrows, dark skin and short hair who was wearing a sports shirt and jeans.
Hussein's two US-based brothers had testified that he had joined the radical Shia militant group Hezbollah, Mr Nisman said.
"The brothers' testimony was substantial, rich in detail and showed that he was the one who was killed," he added.
But independent investigators are sceptical, pointing to repeated incompetence and deception in the official investigation, says the BBC's Tom Gibb in South America.
No proper autopsies or DNA tests were done on human remains at the site. In one of the most shocking incidents, police simply dumped in a bin a head found near the scene thought to have been that of the bomber, our correspondent adds.
The car bomb at the Jewish Argentine Mutual Association (AMIA), which wounded more than 200, was one of two attacks targeting Argentina's 200,000-strong Jewish community in the 1990s.
The 1992 bombing of the Israeli Embassy in Buenos Aires also remains unsolved.
Argentine, US and Israeli officials have all said that Iran is to blame - a charge Tehran denies.
Members of Argentina's Jewish community have repeatedly accused the government of the former president, Carlos Menem, of obstructing the inquiry, something it strongly denies.
In July 2005, President Nestor Kirchner's government issued a decree formally accepting a share of the blame for the failure of investigations into the AMIA attack.