By Silvia Ognibene
FLORENCE, Italy, Nov 12 (Reuters) - Italy on Monday arrested a fisherman for supplying more than a ton of TNT recovered from unexploded World War Two bombs to the mafia, which used them in a wave of bombings that killed 21 people two decades ago.
Police arrested Cosimo D'Amato, 57, on the basis of testimony from turncoat Palermo mob boss Gaspare Spatuzza, who told investigators that he had helped collect the explosives at a port near Sicily's capital in 1992.
Florentine prosecutor Giuseppe Quattrocchi told reporters the source of explosives used to assassinate magistrates Giovanni Falcone and Salvatore Borsellino and their nine bodyguards in 1992 was the same as those for bombings in Florence and Milan the following year that killed 10 people.
"These explosives tie all the massacres together," Quattrocchi said.
D'Amato is a relative of Cosimo Lo Nigro, a mob boss convicted for the bombings, but has never previously been arrested for mafia-related crimes, Quattrocchi added.
The bombings rattled the nation just as the "Bribesville" corruption scandals overturned the political system and swept away the dominant Christian Democrat party.
Falcone and Borsellino are considered national heroes for having successfully prosecuted Cosa Nostra as a single criminal organisation, ignoring repeated death threats.
The mafia's objective with the bombings, according to turncoats, was to force the state to the bargaining table to negotiate leniency for convicted mobsters facing long sentences and harsh prison conditions.
A current investigation is seeking to prosecute both mafia gangsters and politicians accused of being involved in negotiating a deal.
(Writing by Steve Scherer in Rome; editing by Barry Moody)