Legal Question in Landlord & Tenant Law in Washington

Re: Property left by tenant

I am going to guess that what we are talking about is of considerable monetary value. If so, provide the tenant with written notice that since he no longer lives on the premises, if he does not make one final trip to pick up all his belongings by a date that is 14 days from the date of the notice, then his possessions will be considered abandoned, and as such with be disposed of.

That will at least protect you from liability for the possessions. If he keeps returning to the property and is unwanted, your best bet is to seek an anti-harassment order (a type of restraining order) to keep him away under threat of arrest.