Each chief of police, or other official who for the time being shall exercise the functions of the office of chief of police, of each municipality, shall, upon request of the commissioner, cause to be served any subpoena which may be directed to any person residing or being within such municipality. No fee shall be charged for this service by such chief of police or by the members of any municipal police department.
Subpoenas may also be served by any officer as hereinbefore defined, or by any deputy, agent or employee of the commissioner, or of the issuing authority, as the case may be.