Okla. Stat. tit. 58, § 58-180: Issuance and service of citations

If the judge is satisfied that the matter requires

investigation, a citation must be issued to the executor or

administrator, requiring him to appear, at a time and place to be

therein specified to show cause why he should not give further

security. Notice of the citation together with a copy thereof must

be mailed by certified mail to the executor or administrator and his

attorney of record, if any, at least five (5) days before the return

day. If he has absconded, or cannot be found, it may be served by

leaving a copy of it at his last place of residence, or by such

publication as the judge may order.