(1) If, when such proceedings are submitted, the High Court thinks that a further inquiry should be made into, or additional evidence taken upon, any point bearing upon the guilt or innocence of the convicted person, it may make such inquiry or take such evidence itself, or direct it to be made or taken by the Court of Session. (2) Unless the High Court otherwise directs, the presence of the convicted person may be dispensed with when such inquiry is made or such evidence is taken. (3) When the inquiry or evidence (if any) is not made or taken by the High Court, the result of such inquiry or evidence shall be certified to such Court.