Buenos Aires, February 6 (RHC-teleSUR) -- The former spy Antonio Stiusso was called to testify after the investigators checked Alberto Nisman's phone records.

Argentinian authorities haven't yet determined the whereabouts of Antonio Stiusso, a former intelligence agent who was wanted for questioning over the death of Alberto Nisman, a state prosecutor and lead investigator in the deadly 1994 bombing of a Jewish community center in Buenos Aires.

Stiusso's lawyer, Santiago Blanco Bermudez, said Thursday that his client would not be giving testimony. Later, prosecutors say sources confirmed they were unable to locate him at three different addresses held in his name.

Later a top official acknowledged the government did not know if Stiusso, who had been regarded as one of the most powerful operatives in Argentina's leading spy agency, was even in the country.

Nisman had been scheduled to appear before Congress to answer questions regarding his report on the attack, but he was found dead in his apartment just hours before he was to speak.

Government officials have say that rogue agents from Argentina’s own intelligence services were behind the murder and cables revealed by WikiLeaks suggest that Nisman was being advised by U.S. and Israeli intelligence services.