Existing tenants, no lease

[Amanda Williams]

I have a duplex that I am negotiating that has tenants, however the seller isnt able to produce any actual leases. The current tenants aren't either. One tenant appears to have an agreement for month to month, the other thinks they have a 12 month. Any experience with how to deal with this? Since there are no actual leases that can be verified, would I be ok to give 30 days notice to vacate after closing?