Tenant lucknow not paying rent, fraud and cheque bounced

Dear Sir, My Fathers is having 3 BHK flat in Lucknow, Uttar Pradesh. He unknowling Rented out to the Frauds on feb-2016. to Mr B K Sharma pretended to be a branch manager of the co-operative bank at barabanki. He claimed that he will be staying with his wife and child, where her spouse is a housewife. My father assumed he is good a person and Rented out the property with rental agreement for 11 months . 1. Agreement Signed per month rent Rs 8000 + Electricity 2. He issued the cheque for 8000 for 1st month which got bounced. later he paid the rent through bank transfer. 3. From then only he is paying rent but not on time. 4. At present he is having a pendency for 4 months rent and electricity bill for full year and he not staying in the property for 3 - 4 months and at present his agreement also got expired. 5. When ever we are trying to contact him he is not picking up the call, he simply message. he is saying that you can proceed with the possession of the flat i am not going to continue but he is not handingover the keys. 6. My parents are Senior Citizen Please advice what we can do now.