When a crime is happened the police will prepared FIR (a written document - a complaint lodged with the police by the victim of a cognizable offence or by someone on his/her behalf ). Even a telephonic message can be treated as an FIR.
An FIR is a very important document as it sets the process of criminal justice in motion. It is only after the FIR is registered in the police station that the police takes up investigation of the case. The procedure of filing an FIR is prescribed in Section 154 of the Criminal Procedure Code, 1973.
The process of investigation includes, but is not limited to, collecting evidence, questioning witnesses, inspecting the crime scene, forensic testing, recording statements and so on. If the criminals are found, the police will make arrests.
Once the investigation has been concluded the police will record all their findings and file charge sheet before the concerned magistrate under sction 173(2) CrPC. If it is deemed that there is enough proof on the charge sheet the case goes to court. On the flipside, after their investigations if the police conclude that there is not enough evidence or proof that a crime has been committed they can close the case after justifying their reasons in court. If the police decide to close the case, they are bound to inform the person who filed the FIR of their decision.
If FIR is registered against you then if its Congnizable offence, you may be arrested and after that the Investigating officer will collect the evidence in the form of Documents and will also record the statement of witnesses and after deliberating whether the person is innocent or culprit he will file closure report or charge sheet in the jurisictional court. Then the court after carrying out the trial will acquit or convict the accused.
If upon investigation it appears to the investigating officer that there is no sufficient evidence or reasonable ground against the accused he will release (if such person is in custody) provided under section 169 CrPC.
If upon evidence it appears to the investigating officer that there is sufficient evidence or reasonable ground that accused has committed the offence he will be forwarded to a Magistrate empowered to take cognizance of the offence, provided under section 170 CrPC
After the charge sheet has been submitted to the Magistrate concerned he may inquire into and takes the cognizance thereof (from Sections 177 to 189 and sections 190 to 199 respectively) or he may reject the charge sheet straightaway and order re-investigation.
In case charge sheet has been accepted
In that case trial will begun in which both sides i.e. defence and prosecution will present their evidence and witness and the case will be decided in whose favour who will present the clear, cogent and substantiated evidence in respect of his/her case.
If the accused was sentenced he has got opportunity to file appeal against that order.