BUENOS AIRES, Argentina -- Argentine investigators said Tuesday they have found a second person's DNA in the apartment where prosecutor Alberto Nisman was found dead and have called in a witness to check for a match.
Nisman's mysterious death came days after he presented a report alleging that President Cristina Fernandez had conspired to protect Iranian officials implicated in the 1994 bombing of a Jewish community center in which 85 people died. Fernandez and Iran have denied the allegations.
The statement released by the office of Judge Fabiana Palmaghini said she is calling in a person who visited Nisman the day before his body was found. She did not name him, but consultant Diego Lagomarsino has acknowledged visiting Nisman on Jan. 17.
Conspiracy theories swirl around Nisman's death, as well as the bombing, which has never been solved. Polls show many Argentines suspect officials had some hand in the death, while aides to President Cristina Fernandez have suggested he was killed as part of a plot to destabilize and bring down the government.
An autopsy found no evidence that anyone but Nisman was involved in his death. But investigators are trying to determine whether he was killed, committed suicide or was even forced to commit suicide.
Last week, the lead investigator in the case said that Nisman had written draft document requesting the arrest of Fernandez.
CBS News correspondent Manuel Bojoroquez reported that there are growing calls for an international investigation into Nisman's mysterious death and one Argentine congresswoman is looking to the United States for help.
The 51-year-old special prosecutor was found slumped in the bathroom of his apartment on Jan. 18 with a bullet wound in his head. He was lying beside a .22-caliber handgun and a bullet casing. Lagomarsino has said that he gave the gun to Nisman because the prosecutor feared for his life and the safety of his two daughters.
Investigators have said they have no evidence linking him to the death of the prosecutor, though he could face charges of improperly giving him the gun.
Nisman's report accused Fernandez and Foreign Minister Hector Timerman of reaching agreement with Iran to shield eight Iranians, including former senior officials, from prosecution for allegedly masterminding the bombing in exchange for lucrative deals to trade Argentine grains and meat for Iranian oil - allegations they have repeatedly denied.
Nisman was appointed in 2005 during the presidency of Nestor Kirchner, Fernandez's late husband, after a bungled 10-year probe launched under former President Carlos Menem led to a trial in which all of the defendants were found not guilty.