Prosecutors in Italy say the have uncovered a mafia plot to kill the former head of the Italian parliament's anti-mafia committee, Giuseppe Lumia.
Prosecutors say Provenzano ordered the killing in 2000 while still at large
Police have arrested one suspect and have begun investigating another who is already in jail.
Prosecutors say the reputed former head of the mafia, Bernardo Provenzano, ordered the killing in 2000, while he was still at large.
He was arrested last April after more than 40 years on the run.
Meanwhile, the sister of the murdered anti-mafia judge Paolo Borsellino has criticised a court for ordering a softer prison regime for five mafia members, three of whom were convicted of involvement in her brother's murder in 1992.
Rita Borsellino said the law should be changed to prevent repeated appeals.
She said the hard prison regime was a necessary precaution, not a vengeful punishment.