In that 50% of them have some sort of personality disorder and possess communication skills on a 2nd grade level.

Previous owner passed away, son took possession and wants to get rid of the property.

Yes, people got foreclosed on, but the banks got swamped and were often reluctant/unable to physically take possession of all those properties, so many folks just stayed in place and paid nothing.

I would check every day-I would not seek monetary damages(rent) but just seek possession of the property as the agreement you have probably  doesnt address holdover. 

you have to hold all possessions left behind by a tenant for 60 days.

I already spoke to a lawyer and went through the standard process of giving tenants written/verbal notice to pay by XXX date or lose rights to possession of property. 

After taking possession of the home I see that my "rehabbed" house is completely trashed.

The winner of that sale (often the lender) takes possession of the property.With a car loan, the lender has legal ownership of the vehicle and holds onto the title. 

Then he took possession. 

When you get possession, do whatever you want.