The Argentine prosecutor found dead last month was the unwitting "soldier" of former counterintelligence chief Antonio Stiusso, who was seeking revenge for his firing, President Cristina Fernandez's chief of staff said.Anibal Fernandez, who is not related to the president, told Reuters late on Thursday that it was clear years ago that Stiusso called the shots in his relationship with prosecutor Alberto Nisman, who had been investigating the deadly 1994 bombing of a Jewish community center.Nisman was found slumped in a pool of blood, a single bullet to the head, on Jan. 18, days after filing a 300-page document accusing the president of plotting to whitewash his findings that Iran had backed the attack.But the president's chief of staff said it was clear the document had not been written by a legal expert."I am convinced Nisman did not write the charges," Fernandez said in an interview in his wood-paneled office inside the Casa Rosada, the seat of government, late on Thursday. "In his role as a soldier in Stiusso's army, he ended up signing them."Fernandez recalled a 2006 meeting with Nisman over the prosecutor's reluctance to travel to a meeting with Interpol. Stiusso was also present."You realized who was the commander and who was the commanded," Fernandez said.Stiusso was one of the Intelligence Secretariat's most powerful yet enigmatic operatives. Although his career spanned 42 years, only one photograph of the divorced father-of-two is publicly known.In December, he was fired. Sources close to the agency and the government say President Fernandez has been in open conflict with factions of her own spy agency for two years after a shift in relations with Iran that followed a deal in which she enlisted that country's help to investigate the 1994 attack.Iran has vigorously denied involvement in the bombing, and President Fernandez has dismissed Nisman's findings as absurd. She said Nisman was duped by rogue agents and killed when he was no longer of value to them.Sitting in front of a bank of eight television screens, Chief of Staff Fernandez said: "I have no doubt this is part of Stiusso's revenge for having been removed from the intelligence agency ... an organization he thought belonged to him."Investigators confirmed this week they found a draft request for the arrest of the president written by Nisman months ago, suggesting he had been convinced she had plotted to thwart his investigations long before Stiusso's firing.Prosecutors failed on Thursday to track Stiusso down for questioning. Senior officials acknowledge they have no idea if he is in the country.The Argentine government has taken the unusual step of lifting secrecy laws to allow investigators to question Stiusso fully."He should talk and tell everything he wants to," Fernandez said. "If it damages someone, so be it."A staunch defender of the president during one of her worst political crises, the chief of staff has a collection of framed photographs of Cristina Fernandez and her late husband and predecessor, Nestor Kirchner, behind his desk.Conspiracy theories over the prosecutor's death abound, some pointing directly at the president. Polls show the government's credibility has been dented.Even so, Fernandez said the president was unconcerned."Nisman's accusation hasn't given her a moment's worry."