I am sorry to say but if you believe in either party you do not possess the ability to think for yourself.I believe African-Americans and other underprivileged minorities will rise up in my lifetime and so "no thank you" to government social services.

In Alabama, tax certificate owners are entitled to possession as soon as they receive their certificate.

How to take possession of a house that's up for sale .

You need a judgment to get possession of your property. 

You need to send a Demand for Possession for Non-Payment of Rent.  

Do they have legal possession...?

Have him sign a Return of Possession form that documents the date he is returning possession back to you.

I had another thought - if I was you, I would email him and tell him that you do not want photos of the interior of your apartment that show your personal possessions made public in any way, because you are concerned about someone burglarizing your home.That way, he can't just post your personal possessions on realtor.com or Craiglist with the address to where someone can find you lovely, expensive MacBook Pro, for instance.And then if you are burglarized, he gets to pay your renter's insurance deductible, since you forewarned him of your concern. 

In the end, if they don't move out, I will have to pursue the eviction route to get possession of the property.

He took possession Feb 1st, and has had no problem until today.