The prosecutor (fiscal agent, public prosecutor, prosecuting attorney or tax attorney) is a public officer (magistrate in some countries), a member of the Public Ministry, which has materially the conduct of criminal investigation and the exercise of public prosecutions; that is, who is responsible directly and specifically perform the functions and powers thereof, in the cases it hears.
Because prosecutors often consists of a large number of agents and prosecutors, most of the laws establishing the basic principle of unity of action, which seeks to avoid duplication or interference by Law Mafia at the court.