Can I Force People Out Of My Father’s House?

Washington State. My father (70m) lives alone and has been experiencing psychosis for two months. He’s aware he’s not thinking clearly but has refused mental health help—he’s also lost around 40lbs in 2 months as he’s refusing to eat- so I filed a Joel’s Law Petition and within the next week or so, a mental health team is planning to go out and take him into hospital for an initial 120hr hold.

In the last four weeks, he met a homeless woman and invited her to stay at his house for the night. She has now brought a male friend and, as far as I can tell, they are both living in the home with my dad. Neighbors report seeing tin foil and drug paraphernalia on the couple of occasions my dad has changed his mind and asked for help making these two individuals leave. Aside from the drugs, they’ve also robbed my dad and then allowed him to purchase back his possessions, most recently a guitar.

My question is: when he’s taken into hospital, do I have any legal options for making these individuals leave the property? I’m really hoping they won’t be in the house when he leaves, so the crisis team can simply lock the door when they take my dad to hospital but I’m trying to anticipate every possibility here.

My dad invited them to stay but I have very high concerns about them looting the place when he’s gone. As far as I know, they’ve only been there 4 weeks, so I’m not sure about squatters rights.