Wash. Rev. Code § 36.28.090
When there is no sheriff of a county, or he or she is disqualified from any cause from discharging any particular duty, it shall be lawful for the officer or person commanding or desiring the discharge of that duty to appoint some suitable person, a citizen of the county, to execute the same: PROVIDED, That final process shall in no case be executed by any person other than the legally authorized officer; or in case he or she is disqualified, some suitable person appointed by the court, or judge thereof, out of which the process issues, who shall make such appointment in writing; and before such appointment shall take effect, the person appointed shall give security to the party interested for the faithful performance of his or her duties, which bond of suretyship shall be in writing, approved by the court or judge appointing him or her, and be placed on file with the papers in the case.
RCW 36.28.090