False FIR and arrest under section 302 & 201 IPC

My brother has been named as an accused and arrested (currently in Police Custody) in a murder case and section 302 and 201 IPC have been registered in the FIR. The incident happened in the year 2012 wherein the victim (a good friend of my brother) and my brother had went out late night for a night out/dinner. While returning back home they were stopped at a police nakabandi and were asked for identification which was promptly provided by both of them. The friend was riding the bike and he dropped my brother home and was returning back to his place at around 2.45am, he met with an accident on the way home (approx. 1-2 kms away from our place). The body was found next day and panchnama was conducted. The post-mortem report states case of "unnatural death", death was due to suffocation as the victim's bike skidded off the road and he fell into a nullah (murky water was found in his lungs). The victim's mother named my brother as he was the last person to be seen with the victim (police nakabandi being an evidence), whereas my brother was at home when this accident occured. The case is currently in District court and we will be filing it at Sessions court after the remand period gets over. In this case scenario, I would like to know from legal criminal experts on what should be our next course of action, how strong is the case and how can he prove himself innocent in this matter. Although my brother has been in remand from more than a week, no formal inquiry/interrogation has been made. Please guide me.