Police power to investigate cognizable offences allows station officers to act without magistrate orders, subject to supervisory checks. Section 175 authorizes the officer in charge of a police station to investigate cognizable cases within local jurisdiction without a Magistrate's order, while permitting the Superintendent to require a Deputy Superintendent to investigate serious matters. Such police proceedings cannot be questioned for lack of power under this section. A Magistrate empowered under section 210 may, on affidavit-supported application and police submissions, order or supervise investigations and, for complaints against public servants, may order investigation only after receiving a superior officer's report and considering the public servant's explanations.