(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 .