In a veiled reference to the fallout from the mysterious death of a federal prosecutor this month, President Cristina Fernández de Kirchner of Argentina blamed unspecified forces on Friday for provoking upheaval, pleading with Argentines to remain united and to “not let them bring conflicts here that are causing desolation, death and strain on other countries.”

Mrs. Kirchner’s comments came after she moved this week to overhaul Argentina’s top intelligence agency, saying she believed that rogue spies had a hand in the death of the prosecutor, Alberto Nisman, whose body was found in his luxury Buenos Aires apartment on Jan. 18, a pistol on the floor next to him. It is unclear if his death was suicide or murder.

In a statement Friday, Viviana Fein, the prosecutor leading the investigation into Mr. Nisman’s death, said that only his DNA had been found on items taken from his apartment for laboratory tests, including the pistol.

Right before his death, Mr. Nisman had filed accusations against Mrs. Kirchner, claiming that in exchange for Iranian oil, she ordered secret negotiations to shield Iranian officials from charges that they planned the fatal bombing of a Jewish center here in 1994. The government has rejected the accusations, claiming that Iran could not have provided Argentina with the refined oil it required and pointing to a statement from Interpol’s former secretary general that said Argentina had never requested the lifting of arrest warrants for the Iranians, as Mr. Nisman had claimed. He had taken over the case in 2005 after years of inquiry marred by delays and corruption charges.

Mrs. Kirchner has suggested that rogue spies, in a plot to destabilize the government, manipulated Mr. Nisman and had a hand in his death.

In her second public appearance since Mr. Nisman’s death, Mrs. Kirchner gave a televised speech in which she mostly spoke about her government’s achievements and discussed policy developments.

But she also spoke out against unspecified influences that she claimed had sought to wreak havoc. “Here I am,” she said, comparing her plight to that of a naval ship in battle. “A little damaged, but never sunken.”

She also seemed to cast new suspicion on Diego Lagomarsino, an aide to Mr. Nisman who lent him the .22-caliber Bersa pistol used in the shooting. Mrs. Kirchner has called him a “ferocious opponent” of the government, and her chief of staff has suggested that Mr. Lagomarsino is linked to the intelligence services.

Mr. Nisman was buried on Thursday. In an address at the funeral, Waldo Wolff, the vice president of a Jewish umbrella organization, pointed to the failure of Argentina’s institutions to solve the 1994 case. He said Mr. Nisman’s death had “lifted the rubble” left by the attack to reveal the “dark labyrinths of power.”