Jailed Mafia boss of bosses Salvatore 'Toto' Riina has renewed death threats against prosecuting magistrates over an alleged truce deal between the Italian state and Cosa Nostra.
The latest revelations have prompted MPs to demand the matter be referred to parliament.
Riina, who is serving a life sentence in Milan's Opera prison, was taped vowing Mafia vengeance against Palermo prosecutor Nino Di Matteo and his colleagues, while speaking to a fellow inmate and mobster.
"We can't forget this this Di Matteo," Riina was recorded as saying. "Corleone does not forget."
Known as "The Beast" for his brutality, Riina, 83, is a native of the rural Sicilian town of Corleone - a name made famous by the Godfather movie trilogy.
As a teenager, Riina started his quick and violent ascent of the Mafia's ranks and his clan, known as the Corleonesi, eventually came to dominate the Sicilian mob scene.
Speaking to Apulia mafia boss Alberto Lorusso during recreation time, Riina mentioned that an emergency meeting of the committee for order and security had discussed moving Di Matteo to a secret location, after similar threats against the prosecutor were overheard by a prison guard in November.
"He will have to come to the trial anyway," Riina said.
Also known as "U Curtu" - Sicilian for "Shorty" - Riina was arrested in 1993 and is currently standing trial in Palermo over the so-called "State-Mafia negotiation".
A team of prosecutors led by Di Matteo alleges that exponents of the Italian authorities secretly struck a deal with the boss to end his clan's murderous spree in the early 90s.
Sicily was torn by a surge of mob violence in 1992 - 1993, reportedly triggered by the imposition of a hard prison regime for mafia members.
The murderous spree peaked with the killings of anti-Mafia prosecutors Giovanni Falcone and Paolo Borsellino, who were blown up in two separate bombings in 1992, allegedly upon Riina's order.
Prosecutors allege authorities reached out to Riina, who agreed to end the bloodshed in return for more lenient prison conditions for Mafia convicts.
In the bugged conversation with Lorusso, Riina made an explicit reference to the killing of Falcone, voicing threats towards Di Matteo.
"He is to end up like Falcone. He [Falcone] wanted to come see the tuna killing and ended up like a tuna,"Riina said.
A group of Democratic Party MPs have demanded that Interior Minister Angelino Alfano and Justice Minister Annamaria Cancellieri refer the matter to parliament.
"It's compelling for the parliament to be clearly informed so that citizens are made aware of what kind of dangers and threats prosecutors who risk their lives every day to protect legality are exposed to," the MPs said.
Riina is standing trial in Palermo together with his jailed right-hand man Bernardo Provenzano and other mafia members, as well as several high-ranked security officials and politicians, including former interior minister Nicola Mancino and Carabinieri police corps General Mario Mori.
The accused face a wide range of charges including aggression against the state, perjury, and aiding and abetting Cosa Nostra.