The news shocked Argentina. 51-year-old Special Prosecutor Alberto Nisman, who had dominated headlines the previous week with his accusations against the government, was found dead in his 13th floor apartment in Buenos Aires. There were reportedly no sign of forced entry.

“I can confirm that there was a gun, a 22 caliber gun. I can confirm that he died due to a gunshot,” Investigation Prosecutor Viviana Fein said. “I cannot confirm further details. I will find those out in the coming days.”

The 1994 bombing of the Jewish cultural center killed 85 in Argentina’s worst ever terrorist attack. Last week, Nisman accused President Cristina Fernandez de Kirchner, Foreign minister Hector Timmerman, and allies of the government of brokering a cover-up to protect Iranian suspects.

He alleged Argentina and Iran secretly arranged a cover-up to boost bilateral trade between the two countries. The prosecutor had been due to give details of his accusations at a congressional hearing on Monday afternoon in Buenos Aires.

The circumstances surrounding Nisman’s death will make it a challenge for officials to prove his allegations.

“A broad political agreement should take place over how these investigations should be conducted. The government and judicial branch must ensure accurate information is provided to the media and to political parties. But again, that is not in the tradition of how the Argentine justice system functions. On the contrary, it’s a non-transparent system that relies on secrecy, and it is not open to the citizenry,” President of Public Policy Laboratory Alvaro Herrero said.

Nisman had been investigating the bombing for 10 years. With many questions yet to be answered, Argentinians are demanding the death of the prosecutor not be in vain.