Subject to the provisions of this rule, the tribunal may admit evidence by way of a written statement made by a person, notwithstanding that he may not be called as a witness, so, however, that evidence shall not be admissible under this rule if it would not have been admissible had it been given orally.

For the purposes of this rule, a written statement purporting to be made and signed by a person and witnessed by another person shall be presumed to have been made by that person unless the contrary be shown.

Nothing in this rule shall prejudice the admission of written evidence which would be admissible apart from the provisions of this rule.