Palermo, Sicily - A Sicilian mafia boss caught in a massive police sweep against "Cosa Nostra" has been found hanged in a prison cell just hours after his arrest.

The 52-year-old Gaetano Lo Presti was among more than 90 mafiosi nabbed during police raids in Sicily and Tuscany on Tuesday.

An investigation was underway Wednesday on how Lo Presti managed to commit what appears to have been a suicide in Palermo's Pagliarelli prison late on Tueday night, officials said.

Lo Presti, along with the other arrested suspects was allegedly plotting to re-organize Cosa Nostra's command structure under the orders of one of Italy's most wanted mafia bosses, Matteo Messina Denaro, who remains on the run.

Some 1,200 carabinieri paramilitary police, backed by helicopter units and sniffer dogs, took part in Tuesday's operation.

Those arrested face charges including extortion, arms dealing, drug-trafficking and membership of a mafia organization.

Messina Denaro is assumed to have taken over Cosa Nostra9s leadership following the arrest of the previous "Godfather," Bernardo Provenzano, in April 2006 and his alleged successor, Salvatore Lo Piccolo, in November 2007.

However, anti-mafia prosecutors believe that the former Cosa Nostra "capo di tutti i capi" (boss of bosses), Toto Riina, still pulls the strings in the criminal organization, despite having been kept in a maximum security prison since his 1993 arrest. (dpa)