According to www.smartgunlaws.org, the state of Washington requires a background check prior to any transfer of firearms, requires issue of a concealed carry permit if one is requested, but does not require a license to own a firearm. Washington allows prohibition of firearms purchase, in the event a person is found guilty of a domestic violence misdemeanor, similar to the charge 20-year-old Arcan Cetin faced in 2015 when he assaulted his step-father and (according to some reports) incidents with an ex-girlfriend.
Last December a judge told Cetin that he wasn’t allowed to have possession of a firearm, although there have been no reports regarding whether his name is on a “do-not-purchase” list. Cetin shot five people (including a high school sophomore who had survived cancer as a child) at several locations in a department store in a Cascade Mall, then left the rifle on a countertop before departing the mall. Cetin stole the Ruger 10/22 from his step father before committing the shootings.
Amar Cetin is an immigrant from Turkey who has blogged ISIS related material but hasn’t declared radical Muslim justification for his shootings. Cetin confessed to the killings and faces multiple charges for his crimes.
You can find 2d Amendment positions of various Washington office holders here: http://www.ontheissues.org/states/WA_Gun_Control.htm