By Sarah Marsh and Richard Lough
BUENOS AIRES, Feb 5 (Reuters) - Argentine investigators summoned a former spy chief for questioning over the death of a state prosecutor who alleged the country's president had tried to cover up his investigation into the 1994 bombing of a Jewish center, Argentine media reported.
Alberto Nisman was found dead in his flat on Jan. 18, a day before he was due to testify about his claim that President Cristina Fernandez tried to whitewash his findings that Iran was behind the attack in order to win economic favors from Tehran.
Iran vigorously denied involvement in the bombing and Fernandez branded Nisman's findings absurd. She said Nisman was duped by rogue agents involved in a power struggle at the Argentine spy agency, and killed when he was no longer of value to them.
One of those spies was Antonio Stiusso, Fernandez has said.
Stiusso, fired during a December shake-up of the Intelligence Secretariat, or SI, had helped Nisman with his investigation of the bombing which killed 85 people.
Anibal Fernandez, the president's chief of staff, declined to confirm Thursday if Stiusso had been called for questioning. Asked if he thought Stiusso would appear before investigators, Fernandez told reporters: "I suppose he has to otherwise he will find himself in an uncomfortable position."
A spokesman in the office of the lead investigator, Viviana Fein, said he had received no official confirmation from Fein of a summons for Stiusso.
It remains unclear whether Nisman killed himself or was murdered. Conspiracy theories abound, with some pointing directly at the president.
No arrests have been made since President Fernandez's remark two weeks ago that renegade spies were behind the prosecutor's death.
Stiusso's whereabouts were unknown.
"Legally he is in Argentina," Anibal Fernandez said. "But I don't know if he has left the country illegally."
Citing sources close to the investigation into Nisman's death, Argentine news agency DyN and the daily La Nacion said Stiusso had been called to testify at 11:00 a.m. (1400 GMT) in Buenos Aires.
Fein called upon him to testify after checking calls received and made on Nisman's telephone before his death, both media outlets reported.
For years, Stiusso had been one of the most powerful and feared men in the SI. The agency played an important role in the military government's "dirty war" against suspected Marxist rebels, union leaders and other leftists in the 1970s.
Since democracy was restored in 1983, successive governments are widely believed to have continued to use the agency to snoop on opponents. (Additional reporting by Maximiliano Rizzi and Jorge Otaola; Editing by Robert Birsel and Bernadette Bam)