1. IF the Deed was "Registered" before a constitutional authority (means the registrar of sub-assurances), THEN the same is legally & permanently final and non-challeng'ble, becomes irrefutable and now cannot be claimed to be fabricated /fake /whatever .... even by the Courts. Legally there is no requirement of any Forensic report or whatever ....
2. You can file a Police FIR, requesting investigation and charge-sheet, for offences like cheating, intimidation, fraud, breach of trust etc.... against ALL the person/s, supported with all relevant supporting Documents & Witnesses.
3. IF the Police does not take action, THEN you can file private criminal case u/s 156(3) Cr.P.C., in the local Magistrates court, seeking directions to the Police to investigate and file charge sheet. The said Person may come down for settlement.