Last Monday Nisman was due to testify about those accusations. On Sunday he was found dead in his locked apartment with a bullet in his head and a .22 calibre pistol lying alongside him.

The body was barely cold before officials declared this a suicide. Kirchner herself now says it was not, and that Nisman was murdered by people who had fed him false information pretending to be state intelligence agents: “Spies who were not spies.” This theory, of course, conveniently undermines Nisman’s accusations against Kirchner.

Whether Nisman killed himself or was murdered by one of his many enemies, this brave man was undoubtedly the 86th victim of the 1994 bombing, the bloodiest attack against Jews since the Second World War — a crime for which no one has ever been convicted. The attack on the Argentine Israelite Mutual Association (AMIA) and its aftermath is an astonishingly nasty tale of murder, corruption, terrorism and diplomatic intrigue. But more than that, it is an object lesson in the way a state can be fatally undermined by its failure to confront the past.

Imagine if the attacks of 9/11 in America or 7/7 in London had been left unsolved for two decades, its perpetrators unidentified, the families of the victims left uncertain, and you have a sense of the moral outrage sweeping Argentina today.

The elderly Jewish-Argentine occupants of the AMIA building were quietly chatting and playing cards when a 600lb car bomb exploded in front, reducing the structure to rubble, killing 85 people and injuring more than 300. The attack came two years after the bombing of the Israeli embassy in Buenos Aires, in which 29 died.

Argentina’s large Jewish community had little doubt who was behind the attack. Argentine prosecutors, Jewish groups, the state of Israel and Interpol have all accused Iran of orchestrating and financing the bombing, and Hezbollah of carrying it out. Tehran was enraged by Argentina’s decision to cease nuclear co-operation over fears that Iran’s program was not limited to peaceful purposes. Hezbollah was keen to avenge the Israeli assassination of its leader Abbas al-Musawi in 1992 and send a message that no Jewish community was safe.

Yet the investigation from the start was a travesty, a fatal combination of corruption and unwillingness to confront reality. The Argentine political establishment showed little interest in the case. As with Argentina’s Dirty War, many preferred to look away and forget. It was not until 2005 that the former Cardinal Jorge Mario Bergoglio, now Pope Francis, became the first public figure to sign a petition calling for justice in the AMIA case.

That year seemed to mark a change of government attitude. President Nestor Kirchner (late husband of the current president) condemned the failed investigations as a “national disgrace” and appointed Alberto Nisman as a special prosecutor to root out the truth.

Nisman set to work with vigour and courage. A year later prosecutors formally accused Iran and Hezbollah of carrying out the bombing and indicted seven Iranians and one Lebanese-born member of Hezbollah. None has ever been captured and some are still believed to hold government jobs in Iran.

In 2013 the Argentine government announced it had signed an understanding with Iran to set up a “truth commission” to investigate the AMIA bombing. Mrs Kirchner (who succeeded her husband in 2007) claimed it would “advance knowledge of the truth about the attack”. Jewish groups were outraged. Inviting the Iranian regime to a truth commission, said one, was like “asking Nazi Germany to help establish the facts about Kristallnacht”.

The indefatigable Nisman set to work once more, and last week dropped his bombshell. The joint agreement, he claimed, was a sordid secret cover-up: former Iranian officials would be absolved and in return Argentine grain would be exported to Iran and Iranian oil would flow to Argentina to aid its chronic energy deficit.

The talk of justice was a sham, Nisman claimed, aimed at “faking Iran’s innocence to serve geopolitical and commercial interests”. The government dismissed the allegations as ridiculous and now claims that Nisman was the target of a murderous conspiracy to smear Kirchner’s name.

For many in Argentina, the smell left by cover-up, denial and violent death is all too familiar. As the country emerged from the brutal years of dictatorship, those in power chose to hold their noses. Unlike Germany and South Africa, Argentina has never embraced a full reckoning with its grim history.

“We are used to things in Argentina remaining in the dark,” said one opposition politician. Darkness has become a habit. Argentina vowed to establish the truth about the 1994 bombing and never did. Nisman set out to uncover the truth behind that failed promise and died as a consequence. The truth has been abused, degraded and suppressed for so long in Argentina it may never be found.