Mafia boss Pietro Ribisi, jailed for killing a judge and his son, has killed himself, police said Monday. The cause of death, which reportedly took place Thursday, was not made known. Ribisi, 53, was serving a life sentence for murdering Antonino Saetta, president of the Palermo appeals court, and his son Stefano in a 1988 roadside killing. Fellow Mafia kingpins Francesco Madonia and Toto\' Riina were also sentenced for the killing, the latter known for ordering the assassinations of anti-Mafia magistrates Paolo Borsellino and Giovanni Falcone in 1992.