If the case has already been filed in the court in the form of a charge sheet, then you can get a copy of the charge sheet and the full set of papers (including statements of witnesses and the documents relied upon by prosecution) from the court, when you are summoned for the first time in the court. This set of papers is usually supplied by the police itself though it is generally given in the court on the first date. So, if you have not been summoned so far to the court as an accused, wait for that.
Secondly, FIR is nowadays generally available on the website of the district police / state police concerned, where you can select the police station and FIR details to download the FIR. This is as per a judgment of the Supreme Court.
Please note that usually the police station will not provide you the copies of the investigation papers under RTI since they are protected from disclosing such information under the RTI Act. However, as mentioned above, you can try to get the information from the sources mentioned above.
Dr. Ashok Dhamija is a New Delhi based Supreme Court Advocate and author of law books. Read more about him by clicking here. List of his Forum Replies. List of his other articles. List of his Quora Answers. List of his YouTube Videos.