(1) An investigator has the powers conferred by section 171.
(2) An investigator may also require a person who is neither the subject of the investigation ("the person under investigation") nor a person connected with the person under investigation -
(a) to attend before the investigator at a specified time and place and answer questions; or
(b) otherwise to provide such information as the investigator may require for the purposes of the investigation.
(3) A requirement may only be imposed under subsection (2) if the investigator is satisfied that the requirement is necessary or expedient for the purposes of the investigation.
(4) "Investigator" means a person appointed as a result of subsection (1) or (4) of section 168.
(5) "Specified" means specified in a notice in writing.