Section 109(4)(b) in Police Regulations, Calcutta, 1968
(b)Where the assistance of the police is invoked in such cases, police officers shall be guided by the principles followed in the institution and conduct of gang cases. The police officer employed or the purposes of supervision and local control must be of known integrity and experience, and shall go into the witness-box at an early stage of the case to show how the evidence has been got together and sifted. Conspiracy cases shall be under the control of the Deputy Commissioner, Detective Department, or the Deputy Commissioner, Special Branch, who shall report progress from time to time to the Commissioner. In cases in which the sanction of the State Government is obtained or is considered necessary, the Commissioner shall report important developments to the Government.