When new evidence is discovered, that by itself or together with that presented during the trial might justify an acquittal, the convict, his next of kin, his guardian, his heir — if the convict is dead — or the Procuratore Generale presso la Corte d'Appello (the Public Prosecutor attached to the Court of Appeals) may apply to the Court of Appeals for a review of trial. The Court decides de plano with an ordinanza if the application is receivable; if it deems it is not, the losing party can appeal the ordinanza before the Corte di Cassazione. If the Court of Appeals, or the Court of Cassation, deems that the application is receivable, the second part of the review begins before the Court of Appeals itself. During the new trial, the Court reexamines all evidence and can acquit the defendant or uphold his conviction; the verdict is, then appealable before the Court of Cassation. Even if an application for review was turned down before, the convict can apply again, so long as he presents new evidence. A "not guilty" verdict, which has become irrevocable (that has been upheld by the Court of Cassation, that is to say) can never be reviewed.
Other cases of review are as follows:
the conviction was based upon the facts ascertained by a civil or administrative Judge and his judgement has been revoked;
the conviction was the consequence of perjury, bribery or of another crime and the conviction for this crime is irrevocable;
there is discrepancy between the findings of fact contained in the conviction and in another irrevocable one. https://en.wikipedia.org/wiki/Italian_Code_of_Criminal_Procedure