Section 45. If a divorce is granted for a cause constituting a crime, committed within the commonwealth and within the time provided by law for making complaints and finding indictments therefor, the court granting the divorce may, in its discretion, cause notice of such facts to be given by the clerk of the court or register of probate to the district attorney for the district where such crime was committed, with a list of the witnesses proving such crime and any other information which it considers proper and thereupon the district attorney may cause complaint therefor to be made before a magistrate having jurisdiction thereof, or may present the evidence thereof to the grand jury.