On 18 July 1994, the headquarters of the Israeli Argentinian Mutual Association (AMIA) were blown up in Buenos Aires. The car-bomb explosion in the basement of the 100-year-old Jewish community centre was one of the deadliest attacks on the Jewish community in Latin American history, with 85 people murdered and 300 injured.

Since then, there has been much speculation regarding the culprits. The state, under the leadership of then-president Carlos Menem, launched a full investigation. In 2005, Alberto Nisman was appointed head of the ongoing investigation.

Twenty-one years later, on the morning of the 19 January 2015, state prosecutor and lead investigator Alberto Nisman was found dead on the most important day of his career.

He was due to present his case to the Argentine Congress, allegedly deepening the claims which implicated Argentinian president Cristina Fernández de Kirchner, Minister of Foreign Relations Héctor Timerman, elected representative Andrés Larroque, and two prominent trade unionists, Luis D’Elía and Fernando Esteche.

The Buenos Aires Herald, however, claimed ‘Nisman’s report failed to fan flames of conspiracy’ and contained little new information.

Nisman’s death, caused by a single shot to the head, was initially labelled a suicide by lead prosecutor Viviane Fein. Although Nisman had not been physically assaulted in any way, Fein has not ruled out murder.

Nisman had borrowed the gun that shot him from a friend, ‘for safety reasons’, while refusing to accept increased state protection, further confusing the case. No gunshot residue was found on Nisman’s hands.

If, as President Kirchner believes, Nisman’s death is a definite case of murder, who did it? And why?

The powerful rightwing press, led by the Clarín group, have picked up on the event, claiming that Nisman’s theories that the Iranian secret service and Lebanon’s Hizbullah group were behind the 1994 assassinations have now been vindicated.

Initially charging Hizbullah, in 2006, Nisman accused Iran of ‘directing’ the Lebanese militia group. With no obvious motive for this, the only explanation is implicit rather than explicit – that Iran and Hizbullah were using terrorism tactics to kill Jews in secret.

The Hizbullah/Iran allegation came to the fore in 2005, but its origins came from the collaboration of US and Israeli security services, with the FBI claiming Hizbullah involvement. This indictment coincided with the escalating low-intensity war between Israel and Hizbullah, which ended in Israel’s invasion of Lebanon and the subsequent 2006 Qana massacre. Similarly, the Iran ‘connection’ coincided with President Ahmadinejad’s first year in office in Iran and the escalation of US-led sanctions.

The lack of clear motive (why would Hizbullah or Iran target a community centre in Argentina?) and the dubious motivations of the sources of the original claims (the US and Israel), pose a conundrum.

At least, they did until Wikileaks confirmed the politicized nature of Nisman’s investigation. The Wikileaks cables of 2011 revealed that Alberto Nisman had been working extensively with the US embassy on the AMIA case, and that the US had had a direct role in providing the key leads in the investigation.

The key information connecting Iran and AMIA had come from the US via ex-Director of Counterintelligence of the Argentine Intelligence Services (SI), Antonio ‘Jaime’ Stiusso.

An infamous intelligence agent who rose to power during the repressive US-backed military junta of 1976-82, Stiusso was a central operative in the ‘gestapo-like’ business of the SI, allegedly linked to the drug trade. Known for his extensive surveillance of prominent politicians, judges and journalists,he retired, along with his staff, the week before Nisman’s death.

The Wikileaks cables revealed that Nisman was regularly reporting his findings to the US embassy and correcting them accordingly.

In fact, although evidence exists of Argentinian or Syrian agents playing a role in the 1994 attack, the FBI is reported to have ordered Nisman to only blame Iran: ‘Do not aim at the Syrian lead or the local connection. Following these leads could weaken the international case against the accused Iranians.’

Nisman’s indictment against President Kirchner came after she signed a memorandum of understanding with Iran in 2013 in order to establish a truth commission and allow Argentinian prosecutors access to Iranian sources for their investigations.

According to Nisman, Kirchner was ready to absolve Iran of guilt in order to procure bilateral trade agreements with the country (although no trade agreement was ever signed, and trade in fact decreased between the countries following the memorandum).

This was the turning point for Nisman, who indicted the president for aiding the alleged Iranian culprits. He was set to disclose further evidence in his case against the president on 19 January, the day he was murdered.

The deceased prosecutor’s investigation into the AMIA attack had hardly been an impartial or rigorous inquest, yet his death has validated suspicions that the president was desperate to avoid any more information being released.

With Argentinian general elections coming up later this year, the rightwing press has been doing its utmost to undermine the legitimacy of the Kirchner presidency.

The rightwing opposition, the Radical Civic Union, was quick to mobilize its supporters after Nisman’s death, calling for the president’s resignation and using hashtags like #YoSoyNisman (I am Nisman), in an echo of #JeSuisCharlie.

Amidst the mood of confusion and anger, in a country with a long history of secretive killings and state terror, many have questions but few have answers.

The leftwing elements of the trade-union movement have convened a march on 4 February, demanding an end to state impunity. Argentineans are owed greater transparency. And answers.