A woman holds up a picture of late Argentine prosecutor Alberto Nisman outside the AMIA Jewish community center during a demonstration to demand justice over Nisman's death in Buenos Aires January 21, 2015. [Photo/Agencies]

BUENOS AIRES - A prosecutor who accused Argentina's president of trying to derail the investigation into a 1994 bombing, and who died in mysterious circumstances on Sunday, was misled to believe there was a conspiracy to whitewash the crime, the government said on Wednesday.

State prosecutor Alberto Nisman, the lead investigator into the 1994 car bomb attack that killed 85 people at a Jewish community center in Buenos Aires, was found dead in his apartment late on Sunday, hours before he was scheduled to present his case to Congress.

A 22-caliber pistol was found at his side and Nisman appears to have committed suicide, but many of the details of the case are unclear and allegations of foul play have surged. He died just a few days after accusing President Cristina Fernandez of trying to hamper his probe.

A top government official said on Wednesday that Nisman was tricked into believing that two men who formed the backbone of his case against President Cristina Fernandez were government spies.

"They sold him on a connection that did not exist," said Anibal Fernandez, the president's chief of staff.

Asked by a reporter if Nisman had been "totally naive", Fernandez replied: "You said it better than me."