Not able to pay back loan took property and not returning blank cheque

My father borrowed some money from a DP Inspector who was known to my father as a friend and in turn mortgaged our home. The money we took was on interest @3% per month and sometime later due to our business loss we were not able to pay the interest - The Policemen pressured us to give him the possession of the house and in turn he will waive off the interest completely. Later, he sold the house charged compound interest - didnt deduct the money we already paid, and is not returning the cheques he took from us while giving the money. Is highly abusive, and misbehaved with my parents.