Wash. Rev. Code § 11.28.190
Before the judge approves any bond required under this chapter, and after its approval, he or she may, of his or her own motion, or upon the motion of any person interested in the estate, supported by affidavit that the sureties, or some one or more of them, are not worth as much as they have justified to, order a citation to issue, requiring such sureties to appear before him or her at a designated time and place, to be examined touching their property and its value; and the judge must, at the same time, cause notice to be issued to the personal representative, requiring his or her appearance on the return of the citation, and on its return he or she may examine the sureties and such witnesses as may be produced touching the property of the sureties and its value; and if upon such examination he or she is satisfied that the bond is insufficient he or she must require sufficient additional security. If the bond and sureties are found by the court to be sufficient, the costs incident to such hearing shall be taxed against the party instituting such hearing. As a part of such costs the sureties appearing shall be allowed such fees and mileage as witnesses are allowed in civil proceedings: PROVIDED, That when the citation herein referred to is issued on the motion of the court, no costs shall be imposed.
RCW 11.28.190
Fees and allowances of witnesses: Chapter 2.40 RCW, RCW 5.56.010.