18.—(1) No person shall be appointed to carry out an investigation under paragraph 16, 17 or 18 of Schedule 3 to the 2002 Act (investigation by the appropriate authority on its own behalf, supervised and managed investigations)—
(a)unless he has an appropriate level of knowledge, skills and experience to plan and conduct the investigation and to manage the resources that will be required during that process;
(b)if he has any social, financial or other connection, whether or not within the work environment, with the person whose conduct is being investigated which could, on an objective appraisal of the material facts, give rise to a legitimate fear as to whether that investigation can be carried out impartially;
(c)if he works, directly or indirectly, under the management of the person whose conduct is being investigated;
(d)in a case where the person who is the subject of the investigation is a senior police officer and is a member of a force other than the metropolitan police force, if he is a member of the same force as that person.
(2) No member of a police force shall be appointed to carry out an investigation under paragraph 16, 17 or 18 of Schedule 3 to the 2002 Act in a case where the person who is the subject of the investigation is also a member of a police force, unless the officer so appointed is—
(a)of at least the rank of sergeant;
(b)if the officer under investigation is a superintendent or chief superintendent and—
(i)if the investigating officer is a member of the City of London or metropolitan police force, of at least the rank of commander;
(ii)if the investigating officer is a member of any other force, of at least the rank of assistant chief constable;
(c)of at least the same rank as the officer concerned.
(3) In this regulation—
(a)“senior police officer” means a chief constable, a deputy chief constable or an assistant chief constable or, in the case of the City of London police force, a member of that force of or above the rank of commander;
(b)any reference (other than in paragraph (1)(d)) to a member of a police force shall include a reference to a special constable;
(c)any reference to an officer of a particular rank shall include a reference to a special constable of an equivalent rank or grade.