Oregon Revised Statutes Probate Law § 117.005

(3)(a) That, to the best knowledge of the petitioner and after diligent search, the whereabouts of the absentee is and has been unknown for a period stated of not less than one year, and that the petitioner has reason to believe and believes the absentee is dead;

(b) That the death of the absentee at the time, location and in the circumstances stated in the petition is probable, and that the fact of death is in doubt solely by reason of the failure to find or identify the remains of the absentee; or

(c) That there is a presumption that the absentee is dead under the provisions of ORS 176.740.