Murder Laws

Hello Sir/Mam, Greetings.... Last Monday my friend died. Its been more than 6 months we were not in contact because of my job schedules and also because we were far away from each other. I live in Delhi however, studied in Sambalpur, Odisha where my friend died. As per the informations i have received from various people and my friends, they are saying that it was an accident. Everybody is saying that he was under the influence of alchohol and jumped in the lake from a height of 15 ft which is next to imposssible becasue i knw him very well and he cannot do that. he was accompanied by 4 of his friends who informed police abt the incident when they couldn't see him coming out of the water rather than searching him by themselves. Police has not even filed an FIR and has just made an diary entry stating that he was under the influence of alchohol without even waiting for the postmortem report. We are not aware of the postmortem report. I will be reaching Sambalpur by 26th of this month to move further but i only have a weeks leave.... The thing is i am not satisfied with the investigation and want a thorough investigation again. Could you please tell me as how to proceed further. Please... I beg you all.... I hav not lost my friend but i have lost my brother.