The Code of Criminal Procedure, 1973 (CrPc)
157. Procedure for investigations.
(1) If, from information received or otherwise, an officer in charge of a police station has reason to suspect the commission of an offence which he is empowered under section 156 to investigate, he shall forthwith send a report of the same to a Magistrate empowered to take cognizance of such offence upon a police report and shall proceed in person, or shall depute one of his subordinate officers not being below such rank as the State Government may by general of special order, prescribe in this behalf, to proceed, to the spot, to investigate the facts and circumstances of the case, and, if necessary to take measures for the discovery and arrest of the offender:
(a) When information as to the commission of any such offence is given against any person by name and the case is not of a serious nature, the office in-charge of a police station need not proceed in person or depute a subordinate officer to make an investigation on the spot;
(b) If it appears to the officer in charge of a police station that there is sufficient ground for entering on an investigation, he shall not investigate the case.
(2) In each of the cases mentioned in clauses (a) and (b) of the proviso to sub-section (1), the officer in charge of the police station shall state in his report his reasons for not fully complying with the requirements to that sub-section, and, in the case mentioned in clause (b) of the said proviso, the officer shall also forthwith notify to the informant, if any, in such manner as may be prescribed by the State Government, the fact that he will not investigate the case or cause it to be investigated.