Ceremonies in Italy have been marking 20 years since the murder of anti-Mafia prosecutor Giovanni Falcone.

Prime Minister Mario Monti joined thousands gathered in Palermo, Falcone’s birthplace, capital of the autonomous region of Sicily, and the centre of his fight against organised crime.

The anniversary comes less than a week after a bomb attack on a vocational school in Brindisi, on the southern Italian mainland, in which a 16-year-old girl was killed and several others were wounded.

The school was named after Falcone’s wife, Francesca Morvillo. Although authorities have said the Brindisi attacker was probably an individual with no links to the mafia, mourners for the victims demanded gang members be arrested.

Falcone was killed by the Mafia on the 23 May 1992. A 500-kilogramme bomb under the Palermo Airport motorway detonated as his motorcade drove over it. His wife and three bodyguards were also killed.

Falcone’s work had led to a huge trial in 1986 and 1987. This revolutionised the fight against the Sicilian Mafia clans, and 360 mafiosi were convicted.

Fellow anti-Mafia magistrate Paolo Borsellino presided. He was killed by a car bomb just two months after Falcone. The head of the Corleonesi faction of the Sicilian Mafia, Toto Riina, was arrested in 1993 and is now serving a life sentence in prison for those and many other murders.

But suspicions remain over possible roles that others may have played in silencing Falcone. He and Borsellino destabilised political power. For years journalists and prosecutors have been investigating whether there was any state involvement in their assassinations.

Twenty years on, Italian President Giorgio Napolitano said that fighting all criminal associations must be a priority for the whole country.