Investigators say testing of the gun used to kill a prosecutor who had leveled incendiary charges against Argentina's president has found traces of DNA only belonging to him.

Alberto Nisman was found dead in his apartment on Jan 18, hours before he was to detail allegations that President Christina Fernandez protected Iranians accused of orchestrating the 1994 car-bombing of a Jewish center in Buenos Aires.

Lead investigator Viviana Fein said Friday that testing of the pistol and other items has turned up traces only of Nisman's DNA.

She also said a security camera in the service elevator of his apartment building was not working and there were no cameras in its stairwell.

Fernandez has denied any connection to the 1994 bombing, which killed 85 people and remains unsolved.