ROME — One of Italy's most-wanted mafia fugitives eluded capture Monday by climbing through a trap door and into the sewer as police closed in on his hideout in southern Italy, authorities said.

Carabinieri police and divers followed Giuseppe Setola into the labyrinthine sewage system but by late Monday they hadn't found him or the bodyguard who escaped with him, Carabinieri Lt. Domenico Forte said.

"We were on the floor, and they were under the floor," Forte said in a phone interview from Caserta, near Naples.

Setola, a purported boss in the Neapolitan Camorra crime organization who is on Italy's list of the 30 most-wanted fugitives, has been on the run since last year, when he escaped from house arrest that was granted because of an eye problem.

Already sentenced to life in prison for murder, Setola is accused of having masterminded the Sept. 18 gangland-style killing of six African immigrants in Naples — slayings that sparked rioting and prompted the government to deploy 500 soldiers to help police in the violence-ridden area.

Investigators believe Setola orchestrated the slayings to punish the Africans for getting involved in drug trafficking, one of the syndicate's lucrative activities.

Police started closing in on Setola soon after the killings, arresting several members of his clan in an October raid that Setola himself managed to escape.

On Monday, about 50 Carabinieri paramilitary police surrounded his hideout in Trentola Ducenta near Caserta. What they found was a small, 50 square meter (540 square foot) apartment that had a false floor underneath a bed that receded to show a trap door leading to the sewer, all of which was locked with a sophisticated locking system, Forte said.

Forte said Setola a good head start into the sewer since it took so long for police to break through the trap doors. While the sewer conditions are treacherous, Forte said he expected Setola and his bodyguard to survive.

"They are very resistant," he said. "They have stamina."

Setola's wife was left behind and was brought in for questioning, Forte said.