Health, Happiness & Blessings!

Consider contacting the police and the county/city mental health officials.

We all "might" have to sell in a year or two I guess, health pending. 

I would make an appointment with the state or county health sanitarian and go over this before I pulled the trigger.. 

I called the health and safety board and they said its legal.

@Ames Foley I have a couple "store room" type locks on one of my buildings but it's a hassle if you have a tenant move out that you think might be a threat to come back inside using his key.

If she complains to the local authorities about it being uninhabitable, ask the inspector to order her immediate removal for health reasons and you wouldn't owe her anything other than pro-rated rent - which she hasn't paid. 

Its not like lead pipes so you worry about a serious health risk.

Health, job, army, unforeseen circumstances etc. 

Global warming is a serious threat to real estate as well Thanks @Dennis M.