(1) (a) Upon commencement of a formal testacy proceeding, the court shall fix a time and place of hearing. Notice shall be given in the manner prescribed by section 15-10-401 by the petitioner to the persons herein enumerated and to any additional person who has filed a demand fornotice under section 15-12-204.

(b) Notice shall be given to the following persons: The surviving spouse, children, and other heirs of the decedent, the devisees and executors named in any will that is being or has been probated or offered for informal or formal probate in the county, or that is known by the petitioner to have been probated or offered for informal or formal probate elsewhere, and any personal representative of the decedent whose appointment has not been terminated. Notice may be given to other persons. In addition, the petitioner shall give notice by publication to all unknown persons, if the petitioner has reasonable cause to believe that unknown persons may claim an interest, and to all known persons whose addresses are unknown who have any interest in the matters being litigated.

(2) If it appears by the petition or otherwise that the fact of the death of the alleged decedent may be in doubt, or on the written demand of any interested person, a copy of the notice of the hearing on said petition shall be sent by registered or certified mail to the alleged decedent at his last known address. The court shall direct the petitioner to report the results of, or make and report back concerning, a reasonably diligent search for the alleged decedent in any manner that may seem advisable, including any or all of the following methods:

(a) By inserting in one or more suitable periodicals a notice requesting information from any person having knowledge of the whereabouts of the alleged decedent;

(b) By notifying law enforcement officials and public welfare agencies in appropriate locations of the disappearance of the alleged decedent;

(c) By engaging the services of an investigator. The costs of any search so directed shall be paid by the petitioner if there is no administration or by the estate of the decedent in case there is administration.