Asset seizure laws in Italy?

In the news there are always asset siezures that are taken away from the Mafia, alot of the time they are worth Hundereds of millions of dollars/euros. What are the laws though, if they "Suspect" an asset as part of the crime can they just seize it, and then do they give it back after if it's not found as part of a crime? Any good webistes or people with this experience of these laws...