Vehicle related

Hello, I am Ravi from Bangalore. I need help for my unexpected problem i am facing. Actually I had my vehicle to be sold and I had advertised through OLX portal and one party approached for the rate which was reasonable to me and I signed the RTO documents and handed over him to transfer the document. I had sold the vehicle on 30.10.2013. I made a mistake in not verifying whether the person has the vehicle document and after 15 days he alongwith his friend driving the vehicle met with an accident and mowed down one aged person and the case was booked. The pillion rider was the person whom I had sold the vehicle and his friend did the accident. Police filed FIR and booked the case. After some days notice was served on me as the vehicle was still not transferred and the party had not informed me and one fine day I got the notice from Court saying that you have to appear in person or your authorized person. He has made compensation for Rs.5,00,000/- making me and the Insurance company the Oriental Insurance Company as parties. I am totally confused as to how to go about this. I need online help for this