The patterns we see repeatedly
Property fraud in Chennai is not especially inventive. The same handful of schemes recur.
Why both tracks, and in what order
A criminal complaint alone will not undo the registered document, and the police cannot restore possession. A civil suit alone may take years, during which the property can be transferred onward to a purchaser who claims to have bought in good faith.
So we ordinarily file for an urgent injunction restraining further alienation or construction at the same time as the complaint, and register a caveat. Once the property is frozen, the pace of everything else matters far less.
What improves your position
Evidence of payment through banking channels rather than cash. The complete correspondence, including WhatsApp messages, kept intact. The original documents preserved and not annotated. And speed: the earlier an injunction is obtained, the fewer parties there are to unwind.
Where the seller has assets, a claim for recovery of the money paid can run alongside the claim to the property. Which of the two you actually want should be decided early, because it changes how the case is framed.