A woman holding a placard that reads 'We are all Nisman' near Argentina's Congress during a February 4, 2015 demonstration in Buenos Aires following the death of Argentine prosecutor Alberto Nisman. ( JUAN MABROMATA/AFP/Getty Images)

Ever since Alberto Nisman, the Argentinian prosecutor investigating the deadly 1994 bombing of the Buenos Aires Jewish community center, was found dead in his apartment Jan. 18 from a bullet in his head—the day before he was scheduled to testify against Argentina’s president and foreign minister, implicating them in an alleged cover-up of Iran’s involvement in the attack—the story has only gotten more mysterious and troubling.

Nisman’s death, first characterized by the government as a suicide, was soon cryptically described as the work of an anti-government agents. (Others have speculated whether Iran could be behind the murder). Weeks later a Jewish journalist reporting on the Nisman death fled to Israel, citing escalating threats he attributed to the government. Soon after that, investigators found arrest warrants for Argentinian President Cristina Fernández de Kirchner and Foreign Minister Héctor Timerman, dated June 2014, in the garbage at Nisman’s home.

What happened the night of Jan. 18 in Nisman’s apartment, which was guarded by security, may never be fully known. But a new test could offer some information. According to the Buenos Aires Herald, a forensic analysis found no traces of gunpowder on Nisman’s hand, a result which would seem to cast doubt on the theory that Nisman shot himself in the head. Yet the gun in question, a .22 caliber pistol Nisman had reportedly borrowed from a colleague for security, wouldn’t necessarily leave residue on the shooter’s hands, a fact Viviana Fein, the prosecutor leading the investigation, made sure to point out. The test result, she stated “does not rule out the possibility that Nisman had fired the gun himself.”

Further testing will be done on the weapon, with someone else firing it, to see if those results can be replicated. Fein has said there is no evidence another person was present in the apartment at the time of the murder.

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