Section 171 Cr.P.C. deals with a situation when Complainant and witnesses need not be required to accompany the Police Officer they are not to be restraint.

No Complainant or witnesses are required to accompany the Police Officer to any Court, or, are they be restrained by such Officer, compelled to give them security [other than the bond], however, provided the Complainant or witness refuses to attend [the Court] or to execute a bond as directed in Section 170 Cr.P.C., the IO must send that person in custody to the Magistrate, who may detain him in custody till he executes a bond or until the case is heard.