Argentine prosecutor Alberto Nisman–who was found dead in his apartment the day before he was to testify before the Argentine legislature that President Cristina Kirchner had worked with Iran to protect the perpetrators of the nation’s deadliest terror attack–could not have killed himself because if he did, he would have had metal traces on his hands, a new study shows.

The study, released Monday and rekindling a national scandal that has endured unsolved since January, indicates that the gun that killed Nisman always leaves traces of metal on the shooter. Studies conducted in the aftermath of Nisman’s death found no such traces on his hands, indicating that someone else pulled the trigger, or Nisman wore gloves when he shot himself, though none were found on his body.

“Ballistic experts told me that in 100% of the cases that this .22-caliber Bersa pistol was fired with the same kind of ammo [that pierced Nisman’s skull] it would leave traces on the person firing the shot,” said Sandra Arroyo Salgado, Nisman’s ex-wife and a judge in her own right, who commissioned the study. “Nisman was killed,” she insisted, adding that the alternative suicide theory–which prosecutor Viviana Fein has not dismissed–requires Nisman to have “shot himself wearing gloves and, after dying, thrown his own gloves out the window.”

Fein has said the study “cannot be taken as isolated evidence,” and has refused to introduce it as definitive. She also requested that Arroyo propose more direct evidence, “direct proof.”

Fein and Arroyo have been at odds since the beginning of the investigation in January. Arroyo demanded ballistics tests for eight months before Fein authorized them; during most of those months, Arroyo worked to remove Fein from the investigation. Arroyo has called the investigation into Nisman’s death “crappy” and demanded a prosecutor with fewer direct ties to President Cristina Kirchner.

Shortly before his death, Nisman had concluded an investigation into the 1994 bombing of the Argentine-Israeli Mutual Association (AMIA), the deadliest terrorist attack in Argentina’s history. He had found, according to his report, that Kirchner and other high-level officials had offered to protect Iranian suspects in the case in exchange for more favorable oil prices from the Islamic Republic. He had also drafted a warrant for Kirchner’s arrest, though this draft was found in his garbage can.

In response to his death, Kirchner published a rambling, unedited blog post asserting that she believed he was murdered, but that he had been a tool of her political enemies to tarnish her reputation, killed as he was no longer useful. Others in the Kirchner administration were less measured; they were quoted in Argentine media as referring to Nisman posthumously as a “scoundrel” who cavorted with prostitutes.

In addition to the ballistics test, the technology team studying Nisman’s computer and cell phone have found a number of “irregularities” that they deem suspicious. Among them is the fact that his text message and phone call records appear to have been erased shortly before he was found dead. There also appeared to be little to no record of Nisman’s computer activity, including Internet use.

Nisman’s death triggered protests attracting hundreds of thousands of Argentines, many who believe Iran and radical Islamist groups are to blame for his death in addition to the AMIA bombing.