Power to require attendance of witnesses
21.—(1)  In conducting an investigation under this Part, a police officer may issue a written order requiring anyone within the limits of Singapore, who appears to be acquainted with any of the facts and circumstances of the case, to attend before him, and that person must attend as required.
(2)  If that person fails to attend as required, the police officer may report the matter to a Magistrate who may then, in his discretion, issue a warrant ordering the person to attend.