(a) An attested will shall be proved as follows:
(1) By the testimony of at least two (2) attesting witnesses, if living at known addresses within the continental United States and capable of testifying; or
(2)
(A) If only one (1) or neither of the attesting witnesses is living at a known address within the continental United States and capable of testifying, or if, after the exercise of reasonable diligence, the proponent of the will is unable to procure the testimony of two (2) attesting witnesses, in either event the will may be established by the testimony of at least two (2) credible disinterested witnesses.
(B) The witnesses shall prove the handwriting of the testator and such other facts and circumstances, including the handwriting of the attesting witnesses whose testimony is not available, as would be sufficient to prove a controverted issue in equity, together with the testimony of any attesting witness whose testimony is procurable with the exercise of due diligence.
(b) A holographic will shall be proved by the testimony of at least three (3) credible disinterested witnesses proving the handwriting and signature of the testator and such other facts and circumstances as would be sufficient to prove a controverted issue in equity.
(c) A will which has been lost or destroyed by accident or design of some person other than the testator shall be proved by evidence which would be competent and sufficient in a proceeding in equity for the establishment of the lost will. The will so established shall be set forth in the order establishing it.
(d) The provisions of this section as to the testimony of subscribing witnesses shall not exclude the production of other evidence at the hearing on the petition for probate, and the due execution of the will may be proved by such other evidence.