Introductory  Investigation has been defined in law as all the proceedings under the Code of Criminal Procedure for the collection of evidence conducted by a police officer or by any other person (other than a Magistrate) who is authorised by a Magistrate in this behalf. Thus any step taken by a police officer or a person authorised by a Magistrate towards the collection of evidence in regard to an offence would fall within the ambit of the word "investigation" as defined in the Code. In keeping with this definition, the apex Court has held that investigation consists generally of the following steps: Proceeding to the spot, Ascertainment of the facts and circumstances of the case, Discovery and arrest of the suspected offender, Collection of evidence relating to the commission of the offence which may consist of the examination of the various person ....