A man suspected of being a senior figure in the most powerful Naples mafia gang, the Camorra, has been arrested.Giuseppe Setola, who is suspected of 18 murders, was held near Naples. He is believed to be the boss of the Casalesi gang featured in the best-selling book Gomorra. Already convicted for murder and criminal association, Setola is accused of ordering a bloody turf war in recent months and orchestrating the killing of seven African immigrants. He had already managed to escape police earlier this week when he fled through a tunnel linked to the sewerage system beneath his hide-out. He had been at large since April last year after escaping from house arrest which he had been granted for treatment for an alleged eye problem. The killing of the African immigrants in September was one of the most violent crimes attributed to the Camorra in recent years. Police also seized some 10 million euros in cash and properties linked to Setola and his family.