Investigation :

It includes all the proceedings under this Code for the collection of evidence conducted by a police officer or by any person (other than a Magistrate) who is authorised by a Magistrate in this behalf. [Section 2(h)]

The three terms – ‘investigation’, ‘inquiry’ and ‘trial’ denote three different stages of a criminal case. The first stage is reached when a police officer either on his own or under orders of a Magistrate investigates into a case (Section 202). If he finds that no offence has been committed, he submits his report to the Magistrate who drops the proceedings. But if he is of different opinion, he sends that case to a Magistrate and then begins the second stage – a trial or an inquiry. The Magistrate may deal with the case himself and either convict the accused or discharge or acquit him. In serious offences the trial is before the Session’s Court, which may either discharge or convict or acquit the accused. (Chaper XVIII)