Dear Rao garu,
Not an expert in this area, here is some information that might be helpful
Look for these docs.
Try to go MRO office preferably with someone has relevant knowledge and departmental connections to see these documents. Also, ask the revenue officials to help verify the authenticity of the property you are trying to purchase.
Look for these docs online in Webland
1B (sub-registrar won’t register property if this is not in order)
Pass book, Ownership deeds if they have been issued to them.
Take an Encumberance certificate for 33 years.
Ask for copies of the above documents along with copies of the sale deed and link documents (if applicable).
Take these docs to an informed lawyer and get his/her opinion. Get additional information as required based on their feedback.
Ask your lawyer to place an AD in a prominent newspaper soliciting any objections to purchase of property.
If all looks good, you could proceed once your lawyer gives you the green signal.
Hope this helps, good luck with your search.