A senior criminal court judge in canton Ticino has been charged with repeatedly breaching confidentiality rules.
A special prosecutor appointed last week to investigate two top justice officials said he had decided to charge Franco Verda after a second round of questioning on Tuesday.
The special prosecutor, Luciano Giudici, made no mention of the chief prosecutor, Luca Marcellini, who is also under investigation.
Local newspaper reports say Marcellini was due to be questioned on Wednesday. They also say Giudici has ordered all banks in Ticino to hand over details of bank accounts and assets belonging to the two men.
The inquiry into Verda and Marcellini was launched a week ago following a request from the federal prosecutor's office in Berne. The two officials were not suspended, but decided to step down temporarily for the course of the investigation.
Marcellini has denied any wrong-doing. He told reporters that he believed the affair was linked to the arrest last month in Zurich of Gerardo Cuomo, an Italian businessman suspected of fronting an international cigarette-smuggling ring.
Cuomo's arrest followed a request for legal cooperation from anti-Mafia magistrates in Italy. It is reported that while studying the request, the federal prosecutor's office uncovered evidence suggesting that Cuomo may have enjoyed a measure of protection from justice officials in Ticino.
Cuomo was officially resident in Ticino until 1996, and his tobacco import-export company is still based in Lugano.
swissinfo with agencies