Italian police on Wednesday arrested a businessman from Castelvetrano near Trapani, Rosario Firenze, said to be close to fugitive Cosa Nostra No.1 Matteo Messina Denaro.
Also arrested was a surveyor, Salvatore Sciacca, described as Firenze's factotum.
They are accused of mafia association, falsely claiming goods, auction rigging and fraudulently transferring goods.
Prosecutors said the pair rigged tenders in Firenze's favour, with the resulting money going to Messina Denaro.
Four other construction businessmen from Castelvetrano were issued orders to cease doing business while four other people were placed under investigation including two town councillors.
Messina Denaro, 53, has been on the lam since 1993. Interpol has said that the Cosa Nostra boss, whose home fief is in Agrigento, is among the 10 most wanted criminals in the world. In late November Palermo Prosecutor Teresa Maria Principato told the parliamentary anti-mafia commission that police had arrested several members of the his family and seized assets as part of the current strategy to capture him.
"We've arrested almost all of Messina Denaro's blood relations - his sister, cousins, in-laws," she said.
"I thought this might spark a reaction in the man but he's not normal. He's very cold." The prosecutor said confiscating over a million euros' worth of assets was a tactic aiming to hit the mobster's "deep attachment to money".
Italian police in April arrested seven people in the countryside around the Sicilian city of Agrigento in what they said was a continuation of a "scorched earth" policy aimed at trapping the elusive head of the Sicilian Mafia.
But it is a tactic that won't work with him, the prosecutor warned lawmakers.
Police said alleged bosses and accomplices, key parts of a support network for Messina Denaro, held meetings in the fields, walking around to evade possible surveillance devices.
Messina Denaro has not been seen in public in more than 20 years.