It happened to my sister! Frannie went to spend 2 weeks with our other sister in another state and a group of people moved into her house while she was gone. In my state, squatters have many of the same rights as a tenant if any one of the squatters can show:
1) they have received mail addressed to them at the home's address
2) certain belongings of theirs are in the home; functional furniture such as beds and chairs, clothing, and grooming and hygiene items such as toothbrushes etc.
3) they show proof that they have paid toward either the utility bills or property taxes, such as a copy of a check to a utility company or tax board, or copy of a bank statement showing the transaction.
These people had these things and showed them to the police! They had somehow broken into Frannie's house without causing any damage, and in the 2 weeks she was gone they found a current utility bill, took it to a payment center, and paid part of it (#3). They received mail from a business (#1). They moved in two beds, 2 living-room chairs and a loveseat, some dishes, pots and pans, clothes, and toothbrushes and hairbrushes (#2).
Frannie got these people out in a brave way. She lived with them! Her boyfriend and four of their friends moved in and made those people's lives miserable. They helped themselves to any food the people cooked, constantly changed the TV channel, had loud arguements with each other, drank their beer, etc.etc.
It took two months to drive them out, but it would have taken years to get them legally removed, and that's only if they would have won a case against them.