Wash. Rev. Code § 68.50.020
It shall be the duty of every person who knows of the existence and location of human remains coming under the jurisdiction of the coroner or medical examiner as set forth in RCW 68.50.010 or 27.44.055, to notify the coroner, medical examiner, or law enforcement thereof in the most expeditious manner possible, unless such person shall have good reason to believe that such notice has already been given. Any person knowing of the existence of such human remains and not having good reason to believe that the coroner has notice thereof and who shall fail to give notice to the coroner as aforesaid, shall be guilty of a misdemeanor. For purposes of this section and unless the context clearly requires otherwise, "human remains" has the same meaning as defined in RCW 68.04.020. Human remains also includes, but is not limited to, skeletal remains.
RCW 68.50.020