192, may if he thinks fit, postpone the issue of process against the accused and either inquire into the case himself or direct an investigation to be made by a police officer or by such other person as he thinks fit, for the purpose of deciding whether or not there is sufficient ground for proceeding: Provided that no such direction for investigation shall be made: (a) where it appears to the Magistrate that the offence complained of is triable exclusively by the Court of Session; or (b) where the complaint has not been made by a Court, unless the complaint and the witnesses present (if any) have been examined on oath under Section 200. ` (2) If any inquiry under sub section (1), the Magistrate may, if he thinks fit, take evidence of witnesses on oath : Provided that if it appears to the Magistrate that the offence complained of is triable exclusively by the Court of Session, he shall call upon the complainants to produce all his witnesses and examine them on oath.