A petitioner under AS 13.12.530 or 13.12.535 has the burden of establishing prima facie proof of the execution of the will or trust. A person who opposes the petition has the burden of establishing the lack of testamentary intent, lack of capacity, undue influence, fraud, duress, mistake, or revocation. A party to the proceeding has the ultimate burden of persuasion as to the matters for which the party has the initial burden of proof.