( CNN ) Italian authorities have arrested 42 people suspected of belonging to a mafia network in southern Italy , some of whom are accused of extorting tens of thousands of euros from businesses monthly , police said Tuesday . Among the evidence : A piece of paper , hidden in a bicycle handlebar , that listed businesses that the crime syndicate was extorting , according to the Carabinieri , Italy 's military police . The Carabinieri said they made the arrests while raiding homes in 11 provinces . The crime network is based in Casal di Principe , a village roughly 20 kilometers ( 12 miles ) northwest of Naples , police said . The mafia network extorted shop owners to the tune of 200,000 euros a month and extorted operators of slot machines and online gambling a further 100,000 euros monthly , the Carabinieri said . The arrests stem from an investigation that started in October 2012 . Investigators also found notebooks with the group 's organizational chart and names of jailed associates who still were on the mafia payroll , according to the Carabinieri . The note in the bicycle handlebar was among other `` pizzini , '' or little pieces of paper allegedly used by mafia members to exchange information , that investigators discovered in the probe , the military police said . In Villa Literno , close to Casal di Principe , investigators discovered a bunker that allegedly was used to hide fugitive affiliates of the mafia , the Carabinieri said . An anti-mafia prosecutor in Naples filed charges against the 42 , including mafia association , extortion and illegal possession of weapons .
Police say a note hidden in a bike 's handlebar listed extorted businesses . The crime network is based in Casal di Principe , a village near Naples , police say . Arrests stemmed from investigation that began in 2012 .