False fir and arrest

Sir in july2015 one of my neighbours son made gun shot for suicide at my premises. I along with his father, uncle and my son took him to allahabad hospital. He died on fifth day. Police took statements of his father and uncle and they confirm it for suicide. But after few days they started blaming my son for murder. In 2016july additional sp of district confirm it a suicide. But at mean time relative of deceased family transferred in as a sdop and he ordered for fir against me and my son in August 2016 then in February 2017 fir written against my son as a suspected under 302,201,by the time I written to sp, ig, dg, and human rights against sdop. But in February 2018 police arrested me, my wife, and my son and send to jail under 302,201,34.chargesheet is not yet filed. I want to know that how police can make arrest in such a way where one sub inspector, two ti, two sdop, two additional sp have already investigated the matter and found it suicide. The io who arrested my family have changed the spot of accident. Can he do so? Pl guide me how can i come out of this and make such cop be punished. I have also filed 482 in high court.