Naples prosecutors have reportedly opened a criminal probe into the failure to take action in relation to an alarm sounded by the former mayor of Casamicciola, the town on the island of Ischia hit by a deadly landslide on Saturday, four days before the disaster struck.

Former mayor Giuseppe Conte, an engineer by profession, sent a registered PEC email to authorities including the prefect of Naples, the Campania civil protection department and Naples Mayor Gaetano, warning of the danger Casamicciola faced given the forecast of torrential rain and calling for evacuations.

Eight people, including a newborn baby and three other children, are confirmed to have died in the landslide, and the search continues for four missing people.

"I raised the alarm," Conte told RAI television on Tuesday.

"It was necessary to warn these citizens, to tell them 'you have to get out of here because it is dangerous'," he said.

The Naples Public Prosecutor's Office is now investigating the unheeded alarms.

Yesterday in Casamicciola, the mud returned the eighth body found so far, that of 15-year-old Michele Monti.

For the rescuers engaged in the excavation work, the imperative is to act quickly, before a new wave of bad weather, expected to hit the southern regions between tomorrow and Wednesday, makes it impossible to find the four missing persons of whom there are still no traces.

The fire brigade, 160 in action for more than 48 hours on the island, have focused their activity on Via Celario, the road that is no longer there, obliterated by the mudslide that broke away from Mount Epomeo during the night between Friday and Saturday.

There, in the early hours of the day, the body of Michele was found, who with his little brothers Maria Teresa and Francesco, found yesterday, formed one of the two families wiped out by the tragedy.

The family dog was also found lifeless. Still missing from the roll-call are the parents, father Gianluca, a taxi driver, and mother Valentina.