Single-Judge bench held the importance of fair investigation by Investigating officer. And more importantly, advised as following, wrt sec 166A(b), which I elaborated here:

The complainant/victim of a crime may accordingly apply to the Judicial Magistrate, empowered to take cognizance of the offences in question on police report, for monitoring of investigation who can issue appropriate directions for expeditious completion of investigation. The complainant/ victim of a crime may also file complaint under section 166A (b) of the IPC against the Investigating Officer for knowingly disobeying, any direction of the law regulating the manner in which he shall conduct such investigation. In view of explanation to Section 197 (1) of the Cr.P.C. no sanction is required in case of a public servant accused of any offence alleged to have been committed under Section 166 A of the IPC. The complainant/victim of a crime may alternatively file petition in the High Court for transfer of investigation to an independent agency such as CBI etc.. However, it may be observed here that in substantial number of such cases the complainant/victim of a crime is not able to pursue these remedies due to lack of awareness and legal aid at the initial stages.