False dowry death case

Please help me, my brother was married in Febraury 2014 and my Bhabhi committed suicide by hanging from fan in September. No was at home when she committed suicide. When my mother came home from market she saw her hanging and shouted for help and my brother was called. Many nearby people know this. My Bhabhi father filed a case of dowry death on my father mother and brother. In postmortem report it has come that she had a bruise on head as someone has hit her on head with lot of fallen dead hairs in the room cprooving that she was beaten and then hanged which is completely false. My brother is in jail what should I do as i m only free member..? How to prove that we are innocent.. Please help us.. Our happy family is getting destroyed.