Unregistered document & ownership

1)With unregistered document I had found that Person ABC made with the help of SDO Mutation Entry having registration number 2047 of Year 1998 .Person ABC had transferred one land XX on his name( 7/12 ) and other land he tried for transfer but not transferred land YY (Government Right to transfer ) due to permission required from collector office & commissioner office.. 2) When I had visited Registration office registration number 2047 year 1998 is different person name and different property and checked record till 1989 to 1999 his name not found in registration office. 3) For Claiming Right of Property on both XX and YY land of Person ABC what document should I ask because Mutation Entry confirmed Ownership? 4) Can this unregistered document help him to confirming ownership and possession of land. 5) Now 12 year passed now he is considered ownership and Land owner not claimed this property .Which law is applicable for land grabbing in Maharashtra. 6) Approving Mutation Entry is job of SDO this base will save Person ABC for not having criminal complaint against him