Before being satisfied that a prison offence has occurred for which it is appropriate to charge a prisoner, the disciplinary officer, in investigating the alleged offence, must—
(a) review all reports; and
(b) interview relevant staff; and
(c) seek additional evidence, if necessary; and
(d) interview the prisoner, putting the allegation and recording the response; and
(e) check any relevant prison registers; and
(f) consider any special needs or circumstances of the prisoner.