He was a convicted criminal when he prosecuted the appeal. It's extraordinary he was allowed to keep his job and entitles everyone to question his integrity and anything he's ever said about this case.
He didn't win his appeal, he got off on a jurisdiction technicality and now goes on trial again in a few weeks.
Doug Longhini's crimesider series covers what he was convicted of.
http://www.injusticeinperugia.org/crimesider.html
http://www.injusticeinperugia.org/Mignini.html
What were the charges Giuliano Mignini was convicted for?
The charges against Giuliano Mignini are threefold and involve more than just illegal wiretapping. The court convicted Mignini for the following:
1.) Illegally investigating journalists who had criticized him with the "intent to harass or deter them from pursuing their legitimate profession". Specifically the court found that Mignini had targeted Italian journalists Vincenzo Tessandori, Gennaro De Stefano, and Roberto Fiasconaro, because they had criticized his investigations into the death of Narducci.
2.) Ordering an illegal investigation of the Florentine ex police chief Giuseppe De Donno.
3.) Ordering illegal investigations of two officials of the Viminale, the Ministry of the Interior in Rome, including an illegal investigation of the Roberto Sgalla, ex-director of the office of external affairs.