Dear Mr. Vigneshwar,
Criminal code of procedure provides for the limitation with regard to criminal offences. However, in cases that are punishable with imprisonment of more than 3 years, there is no limitation and cognizance of the same can be taken by the Courts.
469. Commencement of the period of limitations.
(1) The period of limitation, in relation to an offence, shall commence, -
(a) On the date of the offence; or
(b) Where the commission of the offence was not known to the person aggrieved by the offence or to any police officer, the first day on which such offence comes to the knowledge of such person or to any police officer, whichever is earlier; or
(c) Where it is not known by whom the offence was committed, the first day on which the identity of the offender is known to the person aggrieved by the offence or to the police officer making investigation into the offence, whichever is earlier.
(2) In computing the said period, the day from which such period is to be computed shall be excluded.
Firstly,you can demand the investigation report and post mortem report from the concnered police station and if they refuse to provide it then you can move an RTI application to procure the same. The practical problem is the officials may claim that they are no longer in the possession of the documents being very old. hence you have to first ask them a query regarding the duration for which they maintain their records.
Once you procure the documents if you have any apprehensions, and police officials refuse to register your case then you can move the local magistrate under section 156(3) CrPC.
The chances are bleak but considering your question, it is always worth a shot.
TC