The ex-wife of the prosecutor whose mysterious death has rocked Argentina criticized the investigation Thursday, calling for an international commission to take up the case and accusing the lead investigator of releasing too much information.

In a late afternoon session organized by opposition parties in Congress, Sandra Arroyo Salgado said she had asked the Public Defender's Office to bring the death of former husband Alberto Nisman to the Inter-American Commission on Human Rights. Calls to the defender's office were not answered.

Arroyo Salgado called on Viviana Fein, the lead investigator, to stop the steady flow of information coming out about the case.

"Overexposure in the media facilitates the impunity of those responsible" for Nisman's death, she said.

The prosecutor was found with a bullet in his head in his bathroom on Jan. 18, the day before he was to elaborate to Congress on his allegation that President Cristina Fernandez had brokered a secret deal with Iran to help shield Iranian officials charged in the 1994 attack on a Jewish community center that killed 85 people. Fernandez has denied that.

The day after Nisman's body was found, Fein said it appeared he had committed suicide. A few days later, she did an about-face, saying investigators were looking at a possible homicide.

That first week, the blow-by-blow of the investigation was shared with the media, sometimes by Fein and sometimes by other government officials. Since then, the flow of information has slowed and Fein has remained tightlipped on most things related to the case.

Arroyo Salgado, who has two teenage daughters from her marriage with Nisman, has expressed concern for her safety and expressed frustration with the investigation. Thursday's speech, which was transmitted nationally by several channels, was the first time she spoke at length and in such a public fashion.

During the speech, she noted the irony that she was speaking to Congress instead of Nisman.

"Unfortunately, I come here to occupy the space that Nisman was going to occupy in Congress," she said.

Arroyo Salgado has requested, and been granted, authorization to send private investigators to Nisman's apartment. She was scheduled to do that Friday, according to a brief published by the judge overseeing the investigation.

Argentine law allows victims of a crime to be have access to the investigation. While hiring private investigators is common in big cases, doing it a nearly a month into a probe has raised eyebrows.

"It's a clear manifestation that (Arroyo Salgado) has no confidence" in the investigation, said Andres Gil Dominguez, a constitutional lawyer not connected to the case.