Wash. Rev. Code § 72.23.180
Whenever a patient dies, escapes, or is paroled or discharged from a state hospital, the superintendent shall immediately notify the clerk of the court which ordered such patient's hospitalization. A copy of such notice shall be given to the next of kin or next friend of such patient if their names or addresses are known or can, with reasonable diligence, be ascertained. Whenever a patient is discharged the superintendent shall issue such patient a certificate of discharge. Such notice or certificate shall give the date of parole, discharge, or death of said patient, and shall state the reasons for parole or discharge, or the cause of death, and shall be signed by the superintendent.
RCW 72.23.180
Disposition of property of deceased inmate of state institution: RCW 11.08.101, 11.08.111, 11.08.120.