Giampaolo Tarantini and his wife Angela Devenuto were picked up in Rome on Thursday morning, police in Naples said. Berlusconi is not under investigation.
Tarantini has admitted he paid a high-end prostitute, Patrizia D'Addario, and other women to attend parties at Berlusconi's residences, but insists the premier didn't know.
He is currently under investigation in Bari for allegedly aiding and abetting prostitution.
Naples Prosecutor Francesco Greco said Tarantini had forced Berlusconi to pay his family legal and housing costs in exchange for Tarantino's cooperation in the Bari prostitution investigation.
Specifically, Greco alleges that Berlusconi's payment was designed to ensure that Tarantino entered a plea bargain in the Bari case rather than letting it go to trial. Such a move would limit the publication of possibly embarrassing telephone intercepts concerning the women who went to Berlusconi's parties.
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