Wash. Rev. Code § 49.17.260
In furtherance of the objects and purposes of this chapter, the director shall develop and maintain an effective program of collection, compilation, and analysis of industrial safety and health statistics. The director, or his or her authorized representative, shall investigate and analyze industrial catastrophes, serious injuries, and fatalities occurring in any workplace subject to this chapter, in an effort to ascertain whether such injury or fatality occurred as the result of a violation of this chapter, or any safety and health standard, rule, or order promulgated pursuant to this chapter, or if not, whether a safety and health standard or rule should be promulgated for application to such circumstances. The director shall adopt rules relating to the conducting and reporting of such investigations. Such investigative report shall be deemed confidential and only available upon order of the superior court after notice to the director and an opportunity for hearing: PROVIDED, That such investigative reports shall be made available without the necessity of obtaining a court order, to employees of governmental agencies in the performance of their official duties, to the injured worker or his or her legal representative or his or her labor organization representative, or to the legal representative or labor organization representative of a deceased worker who was the subject of an investigation, or to the employer of the injured or deceased worker or any other employer or person whose actions or business operation is the subject of the report of investigation, or any attorney representing a party in any pending legal action in which an investigative report constitutes relevant and material evidence in such legal action.
RCW 49.17.260