Buying an occupied property with no leases

[Benjamin Branson]

I'm buying a property out of state. The current owner has no lease with the current tenants. He has done no background check, no credit check. He manages the property himself and collects rent in person. The tenants the owner claims is "Month to Month." How do I protect myself making an offer on this house so that I do not buy an eviction and not know it? Is there a way I can make an offer contingent that the current tenants pass "minimum qualification standards" and sign a lease with me? Has anyone encountered this before?