Suspected death

my brother(21y) missed after went to the office on 10/4/14 after lunch ,his bike at office itself. we didn't got any clues and no communication, no complaint filed but searched with the help of bothers friend. we got info from Railway police body found on track please come n identify on 14/4/14. GRP concluded that suicide, PM report says not written any crushed injuries but says multiple organs injury is cause of death. we have suspect on bro friend, even he bribed GRP SI and doctor. we don't have proofs. we given complaint to railway police to transfer case to civil since we had suspect, copy to HRC, DIG,SP,DSP,SI and CI. case is Registered in HRC. Railway SI says if u have direct evidence i will transfer, he is not co-operating, GRP SI says PM report also says its train hitting. Railway SI has given mobile ase found on body but in mobile there is no sim and memory card and it got little damage.we have consulted local lawyer n going through. is it possible to retrieve Last 3 months voice records from airtel server.Pl help and tell procedures to solve case.