Section 3–406. [Formal Testacy Proceedings; Contested Cases; Testimony of Attesting Witnesses.]
(a) If evidence concerning execution of an attested will which is not self-proved is necessary in contested cases, the testimony of at least 1 of the attesting witnesses, if within the commonwealth, competent and able to testify, is required. Due execution of a will may be proved by other evidence.
(b) If the will is self-proved, compliance with signature and other requirements of execution shall be presumed subject to rebuttal without the testimony of any witness upon filing the will and the acknowledgment and affidavits annexed or attached thereto, unless there is proof of fraud or forgery affecting the acknowledgment or affidavit.