The lead investigator in the mysterious death of a prosecutor who had accused Argentina's president of wrongdoing came under sharp criticism Monday for a video showing police working without latex gloves where Alberto Nisman's body was found.

Ernesto Duronto, vice president of Argentina's association of forensic experts, said many irregularities are seen in the video, which was shot by federal police and obtained by Canal 13.

The video "shows how things should not be done," Duronto said, saying it was paramount for forensic investigators to preserve the cleanliness of a crime scene.

Lead prosecutor Viviana Fein defended her investigation. She acknowledged what the video captured but said it had no impact on the case.

"The crime scene was not contaminated. It was diligently preserved," Fein told Vorterix radio station.

In the video, an officer is seen removing articles from Nisman's safe without gloves. Officers are also seen picking up Nisman's cellphone without gloves and cleaning the gun found at the scene with toilet paper.

Fein said police cleaned only part of the pistol to read the serial number and that would not have eliminated a criminal's fingerprints. Duronto disagreed, saying such an action could indeed smudge prints.

Nisman was found dead in a pool of blood in his apartment Jan. 18. The next day, he was scheduled to elaborate to Congress on his allegations that President Cristina Fernandez had orchestrated a secret deal to cover up the alleged role of Iranian officials in the deadly 1994 car bombing of a Jewish community center in Buenos Aires.

Fernandez rejected the allegations and a federal judge threw out the case in February.

More than four months since Nisman's death, no suspects have been arrested and Fein has said authorities are not sure whether Nisman was killed or committed suicide.