What precautions should I take when buying property with unpaid loan?

I am buying a house without a loan from another person, but he already bought this property on loan, so all the documents are with the bank. He said that if I pay him, he will pay off his home loan, and once the documents are released, we can proceed with the transfer and other sale procedures. Now, I am going to buy this house for 27 lakhs, I have already paid him 10 lakhs, and his loan is still around 12 lakhs. If I don't pay, he won't be able to pay off his loan, and the documents won't be released. If I pay, I will not have any documents for the property, so I am at risk. Any suggestions would be greatly appreciated. They are a good family, and we know each other, but now I don't want to take any risks. I have already paid 10 lakhs, and he paid for another shop he bought. All of this I realized only now.