Alleged Suicide-No Eye Witness - Probable Accident or Murder

Post Incident - Resident Doctor of factory could not identify death or life (confused if pulse was his or of deceased), sent to hospital 100 kms away by factory inspite of existing multispeciality government hospital nearby, factory has first aid room no stabilization or CPR done, no oxygen or medical staff in factory ambulance towards hospital announced brought dead. Statements heavily vary on how the matter was dealt, factory had rumor of murder later planted as suicide, are factory authorities and doctor responsible for 1. negligence if death was not identified 2. Tampering of evidence if death was identified if yes under which laws please. Incident - Brother allegedly fell down from height, police and factory inclined towards suicide, no eye witness no suicide note no apparent reason, PM report inconclusive, plant resourceful, plz guide on getting impartial investigation. Only proof of entry into factory beyond duty hours is verbal by security guard. Body was found within factory.