The special prosecutor whose mysterious death set off a political firestorm in Argentina was laid to rest Thursday, as an investigation tries to determine whether he died by his own hand or was murdered. Alberto Nisman, 51, was buried in a Jewish cemetery on the outskirts of Buenos Aires near several of the victims who died in the 1994 bombing of a Jewish charity known as AMIA. People familiar with his investigation said Nisman had planned to make a bombshell accusation — that President Cristina Kirchner shielded Iranian officials implicated in the bombing.