How do you find out who were prior owners of a house?

The recorder's office or the clerk's office in the local courthouse can show you how to research the prior owners. Or, you could hire a title underwriter to do it for you.

You can find the history of ownership at the county Register of Deeds, or whichever agency is responsible for maintaining land records in your area.

In the game of "snakes and ladder" the snake always aims at it's goal it never misses its prey nor shifts its status nor reverses back

check the rental agreements or property documents.