Editor's Note: This story was updated throughout.

PARIS — Since 2005 Argentine prosecutor Alberto Nisman has been crusading for his vision of justice in the horrific 1994 bombing of the AMIA Jewish center in Buenos Aires that killed 85 people and injured hundreds more. He claimed that Iran was behind it and, more recently, that the Argentine government was trying to block his efforts to prove that.

On Sunday night, Nisman was found dead in his apartment, only hours before he was set to testify before an Argentine parliamentary commission about his allegations.

The circumstances revealed thus far by the police suggest a suicide. The history of Iran’s operations overseas inevitably suggests otherwise. And there are disturbing echoes of the world 20 or 30 years ago when Tehran, often in league with its clients in Hezbollah, waged a global war on the enemies of the Islamic Republic, deploying hit teams second only to the Israelis in their skill at assassination.

First, let’s look at the official communiqué about Nisman’s death issued by Argentina’s Ministry of National Security on Monday morning, with the facts of the case as the ministry said they were known:

Nisman’s lifeless body was discovered Sunday night in his apartment on the 13th floor of Le Parc Tower, which is part of a modern high-rise complex in the Puerto Madero neighborhood of Buenos Aires.

Ten members of the Argentine Federal Police force had been assigned to him as bodyguards, but it seems they were not deployed when he was at home. According to the communiqué, members of the team alerted Nisman’s secretary on Sunday afternoon that he was not responding to repeated phone calls. When they learned that he was not answering the doorbell of his house either and that the Sunday newspaper was still on the step, they decided to notify his relatives.

The bodyguards then collected Nisman’s mother at her home and took her to Le Parc. When they tried to enter, they found the door locked with the key on the inside. They called the building’s maintenance staff who then called a locksmith. Nisman’s mother entered the apartment with one of the bodyguards, and they found Nisman in the bathroom, where his body was blocking the door when they tried to open it. They immediately called police crime scene investigators who entered the bathroom, apparently making as much effort as possible not to disturb the evidence.

Nisman was on the floor with a .22 caliber pistol and one empty shell casing nearby.

The first official communiqué did not say explicitly that Nisman died from a bullet wound to the head, but officials have now confirmed that a shot to his temple was the cause of death. They are still waiting for the toxicology analysis to see if drugs or other substances may have played a role.

Deepening the mystery: investigators report Nisman did not own the gun found with him. They say they are checking to see if a friend might have loaned it to him. They are checking for traces of gunpowder on his hand, but think that with such a small caliber pistol they might not find any. And they are looking at the possibility he may have been "induced" to commit suicide by some form of external pressure. As the case sounds more and more like something from The Godfather or an old James Bond flick, protests have spread in Argentina.

It has been widely reported in Buenos Aires that the documents for Nisman's testimony before parliament were arrayed on his desk when his body was found. In interviews last week he claimed to have uncovered evidence that Argentine President Cristina Fernandez de Kirchner and her foreign minister had made a secret arrangement to give the implicated Iranians immunity from prosecution. Kirchner's chief of staff described the allegations as "foolishness."

How a murderer might have staged this apparent suicide will doubtless be the subject of speculation and conspiracy theories for years to come, as, indeed, is the case with the investigation into the AMIA bombing itself. That never resulted in a single conviction and was called a “national disgrace” by the late President Néstor Kirchner in 2005. The former Archbishop of Buenos Aires, Cardinal Jorge Mario Bergoglio, now Pope Francis, was among those who signed a petition ten years ago calling for justice, but to no avail.

Nisman’s eventual focus on direct Iranian involvement, accusing Tehran of planning and financing the attack and Hezbollah operatives of carrying it out, was not universally supported, even by U.S. investigators who followed the case. “The guilt field was painted with a bit too broad a brush,” former FBI agent James Bernazzani told The New York Times in 2009. Bernazzani had led U.S. investigations of Hezbollah throughout the 1990s and said that while he was “convinced” of the group’s involvement, “we surfaced no information indicating Iranian compliance.”

In the world of intelligence, however, as distinct from the world of criminal justice, there has been little question that Iran was behind the AMIA bombing in 1994 and the earlier car-bomb attack on the Israeli embassy in Buenos Aires in 1992 that killed 29 people.

At the time, the Israelis were attacking Hezbollah leaders and Iranian clients in Lebanon, Hezbollah and Iran struck back wherever they thought they could. “It’s an ongoing game, playing by the rules of the Bible,” a senior official in Israeli intelligence told me at height of the carnage, meaning the rule of eye for an eye, “and at a certain point there is a balance of terror where everyone knows what’s expected.”

The Iranians also targeted with a vengeance any opposition figures they thought might be dangerous. In 1991, after a failed attempt years before, they managed to talk their way into the home of Shahpour Bakhtiar, the Shah of Iran’s last prime minister. He thought they were friends. They were searched by police at the door. They killed him with a knife from his own kitchen. The younger brother of then-President Hashemi Rafsanjani was named as a suspect in the case.

Between 1987 and 1993, according a French government memo published in a very detailed study called Le Hezbollah Global, between 1987 and 1993 some 18 opponents of the Tehran regime were murdered in Europe, and the CIA estimated that between 1989 and 1996 the Hezbollah network carried out 200 serious attacks costing hundreds of lives.

By the late 1990s, the Iranian government apparently decided to slow these operations after several of them started to bring down too much heat. The Germans conducted a relentless investigation of the murder of Kurdish leaders in Berlin in 1992, tracing them back to the then-head of Iranian intelligence, Ali Fallahian. The AMIA bombing in 1994 caused international outrage. And the bombing of the Khobar Towers apartments in Saudi Arabia in 1995, which killed 19 Americans, was eventually traced to another group of Iranian acolytes.

Finally, Imad Mugniyeh, seen as the key Hezbollah operative in many of the group’s terrorist attacks, dating back to the bombing of the U.S. Marine barracks in Beirut in 1983, was blown up with a well-placed car bomb in Damascus in 2008. The Israelis generally are credited with that hit.

But by then, Hezbollah guerrillas in Lebanon had fought a successful war of attrition that led to Israel’s withdrawal from Lebanese territory in 2000 after decades of occupation. Building on that victory, Hezbollah became, and remains, the most powerful political party in the country.

Since then it has focused its actions on a sustained but relatively controlled standoff with Israel, apart from a brutal war in 2006 when it fought the vaunted Israeli army to a standstill. And in the last two years it has deployed in Syria to fight against the Sunni-led rebellion there, including the forces of al Qaeda and ISIS, that threaten the Assad regime.

Iran, for its part, has been trying to show itself a reasonable member of the community of nations by negotiating with the Americans and Europeans about the future of its nuclear program.

Yet there have been signs within the last few days that the game as old as the Bible continues, and may once again grow very dangerous. Last week, Hezbollah leader Hassan Nasrallah boasted that his organization now has weapons that can strike anywhere in Israel. “We have made all necessary preparations for a future war,” he said.

Then on Sunday, Israeli forces killed Jihad Mugniyeh, son of the late mastermind, and several other Hezbollah officers who were operating in the Syrian sector of the Golan Heights. The Israeli press reported they had been planning attacks on Israeli targets.

Was Alberto Nisman somehow caught up in this long war of assassinations? Or did he decide for reasons we probably cannot know to end his own life?

The investigation will continue, unless somebody stops it.