King-Emperor v. Khwaja Nazir Ahmad, AIR 1945 PC 18 has been quoted with approval, several times. The functions of the Judiciary and the Police are ‘complementary’ and not ‘overlapping’. They must be left to exercise their own function, subject to exceptions. Investigation into crimes is the prerogative of the Police and excepting in ‘rare cases’ the Judiciary must keep out. It is not the function of the Court to ‘monitor the investigation process’, ‘interfere in each and every stage of interrogation’ so long as the investigation ‘does not violate any provision of law’.
– Hon’ble Justice R. Banumathi, P. Chidambaram v. Directorate of Enforcement, [Criminal Appeal No. 1340 of 2019].